[RANGE REPORT] GPR-K

Author: Frank Woods

I finally got the GPR-K to the range to zero its main optics. This report is long overdue because of an unforeseen problem that took a while to diagnose and solve. Fortunately, the issue has been rectified and I can speak both on the performance of the rifle as a sum of its parts, as well as go into detail on the problem I had encountered and how I fixed it. The last thing I wanted to do was deliver a bottom line of “This didn’t work out, don’t buy component X.” There’s a bit to talk about here, but different from when I wrote out the build sheet. The data and findings documented below occurred between June 2023 and April 2024.

I decided to zero this using PMC X-TAC 77gr open tip match ammo because it’s common and easy to find in bulk. My logic is that should higher quality ammo like Black Hills or FGMM become available, it wouldn’t be too far off paper if there was any significant difference, so the zero adjustment would be minor.

This decision was inspired by my homie NAVYMAN8903 who made a conscious decision to zero and stock up on ammo with the desired ballistic performance that was common and therefore easy to find, over more sophisticated and rare varieties of ammo (because Barnes VOR-TX 70gr and Black Hills TMK is a bitch to find; I think the latter was discontinued, unfortunately).

ZEROING

I started with the irons, zeroed at 50; I reckon if I need to use my irons, I want my primary sighting system to have less guesswork with hold overs and hold unders closer in. I removed the optics package (LPVO + ACRO P-2 on Reptilia mount) using one of the hex keys I purchased to keep in my kit for that purpose in case something catastrophic happened to my optic. Once I stowed the LPVO assembly, I flipped up the irons, proned out, and got to work.

The irons didn’t fight me; three five round groups got it to where I was happy, in the ~4″ circle at 50. I shot another five round group to confirm and moved onto the next task, this time the ACRO P-2, also at 50 yards. Since one of the reasons the ACRO is situated where it is is passive aiming through Night Vision, I would rather it be zeroed at a distance I can more clearly see and PID my target under NV. Using the head of the target, I shot a five round group and hit low right.

I dialed in the corrections and shot another five round group at the head and ended up with a nice tight little Y shaped group right in the center of the head of the target. Seeing it was dead on, I didn’t feel the need to shoot another group to confirm. Now it was time to zero the NX8 1-8x at 100.

I go for 100 with the main optic usually because that’s what the manual calls for relative to the reticle and for holds, unless otherwise noted in said manual (this is the case with the Leupold Mark 6 1-6x with the CMR-W reticle, which calls for a 50 yard zero). To make life easier, I get it zeroed at 50 first, and if I don’t fuck up, I’ll only have a minor elevation adjustment for 100 yard confirmation. Using the X ring, I got two groups that were decent enough that I felt comfortable going to the 100 yard target.

That the second group was larger than the first didn’t concern me; if anything, the first group is testimony to the rifle’s precision capability. I attribute the second group’s larger size to my prone position while using an ammo can as a rest introducing stability inconsistencies. So if the group is centered around my desired POI at whatever particular distance, I’ll take it as a win.

There is a small agency logo in the top left corner of the target measuring about 2×2.5″; The circle is 4” wide inside the ring. I will utilize both the circle and/or head and the agency logo as points of aim, first to verify windage and elevation in the circle, then to confirm those in the head, and then to finally confirm zero on the smaller target (aim small, miss small) once I’m satisfied with what the adjustments are telling me on paper.

On this target, the first rounds fired were in the circle where the initial adjustments were made. The head and agency logo were used alternately to fine tune and verify the adjustments. The last five rounds were after I shot the second group on the agency in the logo and was reasonably satisfied despite the two low fliers and said to myself “Put five in the neck and if windage and elevation are on, call it a day.” Considering the improvised barrel rest, I was happy with that group.

Once this was done, I slipped the turrets and zeroed them out. Then I had one more zero to check; the training ammo deviation. I loaded up some 55gr XM193 and fired at the target; the offset was unremarkable, a mere .4MRAD Down and Right was all it took. I noted that down for DOPE and to make a drop chart for both varieties of ammo that noted the zero adjustment between them to tape on the scope later, a trick I picked up last year from another .gov employee shooter I met.

Now when I’m going to a class using 55gr FMJ, theoretically I should just have to dial two clicks in either direction for a total of .4MRAD Down and Right, and that should set my zero for that ammo variety; if any minor adjustments from there due to atmospherics are needed upon confirmation, I’ll make note of it in my log.

DIAGNOSTICS

Mechanically speaking, the rifle performed aces internally as far as cycling goes. This was especially surprising considering every round fired was shot suppressed via the Surefire SOCOM556-RC2; I had forgotten to lube the rifle, but despite that it didn’t choke once.

Speaking of suppressed shooting, the SilencerCo GDCH was actually REALLY good at what it was designed to do. At no point did I experience stinging teary eyes or inhale excess blowback that’s typical of firing a DI AR suppressed; I was wondering why that wasn’t happening for a minute before I remembered the charging handle’s specialty and said oh shit, this thing is legit. In that respect at least.

The charging handle did have a noteworthy failure however; the roll pin that retains the right side pull lever came loose, and the whole thing fell out. My friend that was with me noticed the pull lever fall off, and that’s when I realized the roll pin had walked out the bottom of the charging handle. Thankfully the upper receiver caught and retained the pin from falling out of the charging handle entirely, or else that would have been a pain in the ass to find in the sand amidst all the shell casings from over the years.

I put the pull lever back in place and tapped the roll pin back in with my Leatherman Wave multitool as an improvised hammer. I got it in there snug and this did not happen again for the remainder of the rounds fired. However, this wouldn’t be the first time it happened; on the second outing with this rifle when I was doing a function check on the bolt catch, the same thing happened on the other side of the charging handle.

I would consider this a catastrophic failure of the charging handle for the fact that the left side pull lever is the one we typically use when loading the rifle or cycling the action to clear a malfunction, regardless of whether or not it’s ambidextrous or a standard one sided charging handle (with or without an extended latch). This time, I had to disassemble both sides of the charging handle and rebuild the whole thing at the bench with an improvised punch and hammer, to make sure the spring was properly aligned inside.

My friend Nate warned me about this happening on agency rifles where he works, and I thought I had avoided it by skipping the “Gen 1” prototype and going straight for the “Gen 2” version I thought I had. This was not the case however, but it was unacceptable that this issue had presented itself two range trips in a row without any hard use on the charging handle in particular.

I contacted SilencerCo customer service, and as it turned out, this was not the latest version of the charging handle as I stated in the build sheet article; it was an upgrade from the original prototype, but not the most recent permutation. The current model ditched the roll pins entirely, and replaced them with threaded posts; a completely new design. They sent me a new one in time for me to install it before an upcoming class I intended to use the rifle for. The new design appears to be much more robust and secure than the previous roll pin models; When I received it, I did some cycles on the charging handle as though I were clearing a jam; neither side of the charging handle came loose, nor did the screws unthread from the charging handle.

However, in January about a week after SHOT during a diagnostic shoot, one of the screws did back out and allow the right side charge handle latch to fall out. I noticed right away, reinstalled the latch and torqued down the retaining screw, making note to apply some loctite to the threads later on since I had none with me that day. A minor inconvenience if anything, especially compared to the trouble I was experiencing with the bolt catch. This is where the story gets twisted.

One quirk we noticed, this time involving the SilencerCo SCO-15 lower, was that the bolt would prematurely lock back when one round was left in the magazine at random/inconsistent intervals. The first time, I was using BCM and Duramag USGI pattern mags; we also tried it with a Gen 2 and Gen M3 PMAG. Sometimes it happened, sometimes it didn’t.

Either way, I got into the habit of looking into the ejection port to see whether the mag was empty when I felt it lock back, or if there was one round left, at which point I would hit the bolt release and fire that last round. The bolt carrier would lock back again once the mag was empty.

We did notice however, that unlike a typical bolt catch you’d see anywhere else, there’s extra material coming down from the bottom of the tooth on the SCO-15 ambi bolt catch that sticks out to make contact with the follower as it comes up once the last round is fired to facilitate the bolt catch function. This feature is consistent across four SCO-15 bolt catches I own.

We theorized that the added material was hitting the follower prematurely, causing the bolt catch to go into effect one round early; but since it wasn’t happening every single time there was only one round left in the mag, we weren’t absolutely sure. I talked to a friend of mine that used to work at SilencerCo and asked him if he’d ever seen anything like this in testing; he said I was the only other person he knew of besides himself that had encountered it. I wanted to make sure before I made an irreversible reductive modification to the part; how did he fix it?

He confirmed my hunch and told me he fixed it by removing the extra material from the bolt catch tooth that the follower lifts after the last round. So I popped the piece out of the lower, took it to the grinder wheel, and removed that extra material, machining the surface flat just like every other AR pattern bolt catch in existence.

After modifying the component, I took the rifle to the range again for function check (this was the second time, when the left side charging handle latch fell off the first version), to see if the modification solved the problem. Good news: The premature locking of the bolt to the rear while one round remained in the magazine problem went away and did not repeat itself once during the function check. Bad news: Now a new problem had come up.

FROM THIS POINT FORWARD, NOTE THAT EVERY VARIATION OF EVERY TEST CONDUCTED IN LIVE FIRE AND NOTED HEREIN WAS DONE WITH MULTIPLE RELAYS OF 2 ROUNDS × 10 MAGAZINES, FOR EVERY SOLUTION ATTEMPT

https://youtu.be/eS1tQXjiEEI?si=G-b8FfdDnit-TguM

This time all I had was the same black BCM & DuraMag magazines from before, plus a gray USGI mag that’s green follower vintage. Consistently throughout the range session, the OD green DuraMag failed to lock back on empty. It was rare that this didn’t happen and locked back as normal; most of the time this malfunction did occur. The other two mags worked fine, as you can see in the video above. I think only one of them failed to lock back once the whole day, I don’t even remember which one it was between the gray and black mags.

https://youtu.be/yiT5AjAfgnY?si=83vyr_FghydPcRr8

I also borrowed mags from the guys next to me at the range (one of whom was nice enough to record the issues as they occurred so I could show you here.) One was a ProMag, the other two were Troy polymer mags. Neither of those had any problems either, so now I wasn’t sure what to make of it. I brought the issue to Tactics & Applications to see what they had to say. Long story short, they said it could be one of two things: Either the DuraMag was unserviceable and needed to be tossed, or the Geissele Super 42 spring needed to be switched out with something more standard; apparently it has a track record of being uncooperative in this regard, whereupon it forces the bolt carrier forward faster than the bolt catch can rise to meet it.

To save time and make a long story shorter, what followed was a series of diagnostic testing via trial and error to determine exactly what was causing this lock back failure and how to fix it so it would stop happening. Among all the things we tried…

https://youtu.be/KYTN8DvM9Kk?si=7lHZMekr0tmc4H7Q

• Increased magazine testing sample size from 3 to 10, over a wider variety of manufacturers and magazine ages: Magpul Gen 2 & Gen M3 30 round PMAGs, Magpul Gen 2 20 round PMAGs, Okay Industries USGI, BCM USGI, 2x DuraMag USGI, DSG USGI, US Army EPM, and FN USA USGI mags. With two rounds loaded in each mag, one for a full cycle and one for a lock cycle, the test was to see if all ten magazines could be fired without a single lock back failure. Not only was this a failed effort, but each relay of ten mags was inconsistent; some mags would pass and some would fail on each relay, but never the same mags either way.

• Multiple combinations of Sprinco springs and buffer weights: Red, Blue, “Hot White” (Red & White), White, and Orange, with H, H1, H2, and H3 buffers, fired both suppressed and unsuppressed. The theory was that the back pressure from the RC2 suppressor was overgassing the BCG to the point that it was outrunning the bolt catch. While some of these combinations were successful unsuppressed or suppressed, none of them allowed the weapon to flawlessly cycle either way.

• Rebarreling the rifle: After speaking with Jim Hodge it was determined that the original 12.5” barrel was the .0645” gas port version meant to accommodate a wider variety of ammo; the .0625” gas port version that was optimized for M855A1 ammo pressure and suppressor use was purchased and installed. This did not solve the problem, and as Jim noted, both gas port sizes were within his barrel spec and should have worked suppressed or unsuppressed with an H2 buffer and a standard spring.

• Shaving down the bolt catch lever: It was thought that perhaps the added mass of the right side of the bolt catch was putting too much weight on the part and prevented it from lifting with the mag follower when needed. However, removing some excess material from the bolt catch lever and switching out the bolt catch plunger spring to ensure it wasn’t too light did not solve the problem, either.

https://youtu.be/6ju3mkB8IDg?si=4ztE44ISzFo1EpN4

• Swapping lower receivers: This was where we started trying to eliminate variables introduced by the SCO-15 lower itself; first we put the GPR-K upper on the MGS4 M4A1 lower just to see if these problems were unique to the upper or lower. No issues came up from using the GPR-K on the plain Jane USGI lower, however the MGS4 M4A1 upper did experience a few instances of premature bolt lock on the SCO-15 lower.

https://youtu.be/NknUd4EKgI0?si=3EK989MXB7gvz_Ep

• Bolt catch swap: This is where we narrowed down that the SCO-15 bolt catch was the unique catalyst. We tried it both ways: Putting the whole GPR-K upper on a plain USGI lower, and putting a USGI bolt catch in the SCO-15 lower. In both cases, every relay of ten magazines with two rounds each was a success; multiple relays showed zero lock back failures, with the rifle suppressed and unsuppressed.

Things started looking bleak here. Could it be that the SCO-15 lower’s claim to fame was in fact a design flaw? A search through reddit (enter this into the Google search: sco-15 suppressor bolt lock site:www.reddit.com) and a later polling of end users discovered that multiple people had experienced the same two failures, premature bolt lock and failure to lock back at all, using the SCO-15 lower with a wide variety of upper receivers in various barrel lengths, both suppressed and unsuppressed. I brought my findings and concerns to my friends over at SilencerCo R&D; they told me to send in the whole rifle for them to inspect. I removed all the enablers except for the iron sights, boxed it up, and sent it over to them.

They replaced the bolt catch component with a fresh one that hadn’t been chewed up by the bolt lugs skipping over the top of the bolt catch, put the rifle in a vise, and started shooting both the rifle and high speed cameras to watch what was happening to the rifle as it cycled, both unsuppressed and with an RC2 attached. At first they couldn’t get the issue to repeat itself. I asked which ammo they were firing and they said M855; I told them to switch to XM193 like I had been using. Then they were able to get the lock failure problem to occur multiple times. The final verdict was that the suppressor was so boosting the BCG, that it was overriding the bolt catch as suspected previously. Being that the barrel with the smaller gas port hadn’t fixed the issue, it was thought that only an adjustable gas block could tame the matter, as SiCo’s engineers had done with it while they had the rifle there.

The other thing I was told was that this problem wasn’t one encountered during engineering of the SCO-15 lower and that it was more likely than not that haphazardly assembled and/or overgassed uppers were the root cause; I knew this couldn’t be true though. It couldn’t be that the likes of BCM uppers suffered such problems as others on reddit had testified to using in their similar experiences, and I knew I had assembled the upper proper. I also knew I couldn’t tell as many people, “The lower is fine, your uppers are wrong.” There had to be another answer.

I really didn’t want to put an AGB on the rifle, for all the reasons one would be encouraged to avoid an AGB; I didn’t want to have to keep a tool handy to adjust the gas block, nor did I want to run the risk of the gas block seizing and becoming unadjustable or not true to its adjustment range. But there was one more thing I hadn’t tried. Right before SHOT, two things happened:

1.) I ordered two HK ambi bolt catches that were similar in form factor to the SCO-15 variety, which by the time SHOT happened had not yet arrived.

2.) I fired the GPR-K upper on a DSI MFR lower, which itself used a likewise similar ambi bolt catch to the HK and SCO-15 versions.

In the case of the former, while I hadn’t yet had the opportunity to test the HK bolt catch in my lower, a friend of a friend was having the same issues with his SCO-15 lower, and my friend told him I had ordered the HK bolt catch to see if it would help. He went ahead and ordered one himself and when he tried it out in his SCO-15 lower, he reported zero issues, no occurrences of premature bolt lock or bolt lock failure. That was encouraging.

In the latter case, I had the same experience. Using the DSI MFR lower, there were no failures and everything functioned as it should have. This was extremely impressive considering the small town background of DSI and its design team; here they had engineered something that did the same job as a product designed by a much larger company with a heavier presence in the industry, but better performing of the same task. We tried to put an MFR bolt catch in the SCO-15 lower, but the parts geometry between the lower and bolt catch didn’t match up and the bolt catch wouldn’t fit in the SCO-15 lower. Not the worst bit of news, because now we knew: There was a way to get this thing working that didn’t involve an adjustable gas block needing to be installed.

https://youtu.be/3MgRwecs-NA?si=9raFq6dq28VDwIAE

When I got home from SHOT, I dropped the HK ambi bolt catch in the SCO-15 lower, and when I closed the receivers to attempt a dry function check, I had a problem: I could barely move the bolt catch. This was strange, considering my friend said his friend had no problems with it. In my stubbornness I had forced the bolt catch up and down a few times, which had revealed the problem: Tolerance stacking.

As it turned out, the walls of the SCO-15 upper are thicker inside than a standard USGI upper, which I had confirmed my friend’s friend was using. I determined this when I noticed the wear markings both on the corner of the bolt catch, and the inside wall up the upper receiver immediately above it. Well this was nothing to be discouraged over, I had two HK ambi bolt catches, one to serve as a control. The solution was obvious: Some material needed to be shaved off the HK ambi bolt catch to provide clearance within the thicker walls of the upper. I took the part out of the lower, brought it to the garage and removed some material, like so:

https://youtu.be/2yXCT2S0u3A?si=seUlqI0Ku2u2wmDh

You can see the modified HK ambi bolt catch above the control unit in the picture above. Once this was done I reinstalled it into the SCO-15 lower, and gave it a dry function check: A few flicks with the trigger finger to ensure it could move freely inside the rifle as it should have, and a few charging handle pulls with empty mags inserted to ensure lock back on empty. Both were successful… now it was down to a live fire function check to determine if it actually worked.

SUCCESS

https://youtu.be/cXs5buf_RxA?si=8rK39Wpqmkq4OXtQ

After nearly two cases of ammo (~2000 rounds, most of it XM193 spec) had been shot through this rifle during all of this diagnostic testing, I was relieved to discover the working solution in the form of the modified HK ambi bolt catch: One relay of ten mags/two rounds each, unsuppressed to serve as a control, and three relays of the same while suppressed, all using an H2 buffer and a standard carbine spring for a total of 80 rounds fired across a sample of 10 mags, produced ZERO malfunctions of either premature bolt lock or failure to lock back variety. Finally.

Having solved the problem, I can now say with satisfaction that the rifle meets or exceeds all performance expectations. My hope is that SilencerCo will consume this data to engineer a new bolt catch that eliminates both the premature lock and lock back failure malfunctions all together. It can be done, and without an adjustable gas block.

Out of mere curiosity, I wanted to try one more thing before I closed the book on the diagnostics. During the Black Friday sales season, Griffin Armament had their MK2 ambi lower on sale. All told it was less than $200, and being an ambi lower aficionado it would have been stupid for me to not grab one, especially at that price. I don’t know the whole story behind it and the tech licensing, but the Griffin MK2 lower is pretty much an ADM UIC-15 lower, only it’s forged instead of billet. Since my existing ADM lowers never gave me a problem with suppressed or unsuppressed uppers, I wanted to see if this one had the same issue with the GPR-K upper or if it would work straight from the get go.

I removed the H2 buffer and carbine spring from the SCO-15 lower and installed them into the Griffin MK2 lower after I put an LPK into it, and dropped the GPR-K upper with the suppressor on the muzzle onto it. I set up a relay of ten mags with two rounds each, and about 3 or 4 mags in I experienced a failure to lock malfunction. I cracked the receivers open to inspect the bolt catch. Sure enough, there was a small chip along the top where the bolt had skipped over it before it could lift fast enough to catch it once the mag was empty.

The thing with the ADM and Griffin lowers, however… the bolt catch is a proprietary component. There is no switching it out for another likewise part made by another company. What you see is what you get. Having just solved this issue with the SCO-15 lower, and not wanting to go back through another whole round of diagnostic testing with different buffer and spring combinations, I shook my head with a laugh and chose to take my wins where I could get them and decided not to poke the bear with a whole new lower. I put the GPR-K upper back on the SCO-15 lower, and set aside the Griffin MK2 lower as a spare that I would make a new rifle out of with its own upper one day at some undetermined point in the future, or just keep as a testbed lower. Hopefully without this problem.

FIELD EXPERIENCE

I did have two opportunities to use the GPR-K in training settings, once before I fixed the bolt catch problem, and once after. The first was at DARC during the TUSC class in September 2023, where the only modification I had made was swapping the BCG with a UTM version to fire blank UTMs out of the rifle for simulation purposes, paired with a Surefire Trainer version of the RC2 suppressor. Surprisingly enough the rifle exhibited zero issues locking back on empty while cycling the blank UTMs, even without switching to a lighter spring or buffer. That struck me as strange but I was happy I didn’t have to deal with clearing malfunctions during any of the mock gunfights. I lost a few pieces of the rifle along the way, but I’ll get into those details in a moment.

More recently, I brought the GPR-K to Pressburg Ridge for another invite-only training session, and a stack of Gen M3 PMAGs fresh out of the wrapper. For all the rounds I fired (close to 1,000 if not more), the rifle didn’t give me a single lock back related malfunction; it never locked back prematurely, and it did lock back every time the mag ran empty. The only malf I experienced, maybe four or five times across three days, was a weird hybrid of a failure to extract with a double feed: it looked like a double feed, but one round was the spent shell casing and the other was a fresh round coming off the mag.

Our theory was the bolt carrier was traveling back far enough to strip a new round off the top of the mag before the ejector could jettison the empty casing. Since it was an inconsistent and intermittently occurring malfunction, I attributed it to the rifle being dirty; I haven’t cleaned the thing in a while and I fired it suppressed the whole time and just kept adding lube throughout the class. I’ll keep an eye out for it once I give it a good cleaning, but I’m not worried that it’s a new problem like the bolt catch was before it. More often than not, the rifle ran perfect under sustained fire:

https://youtu.be/dB1wzAWumTs?si=-V5vSVJAL-MmoX4E

WHAT CAME LOOSE?

Every time I shoot a new gun for the first time once it’s all put together, rifle or pistol, one of the things I look for at the end of the session is, what came loose? No matter how much torque we put on fasteners, something always manages to come loose when we don’t expect it. I look all over the gun where stuff is screwed down into or onto it and give it a pull and a shake to see if anything’s rattling.

This first time I took it out, it was just the Arisaka M-LOK inline Scout mount for the weapon light. In particular, the M-LOK T-nuts unseated by a few turns, so the light and mount were hanging tilted off the flat surface of the RIS III rail. It was retained, but if they kept turning the whole assembly would’ve been hanging by the switch cable like a lanyard. I repositioned the screws and tightened them down with gusto this time (I don’t have an inch-lb driver to check torque, fuck off) and it was back in place where it needed to be.

While at DARC TUSC, my rear Tenebraex scope cap got lost to the aether, forever lost God knows where on the property that its earth-toned coloration blended into. I did a walkback and retraced all my steps the day I noticed it was missing, about halfway through the day but to no avail. I just ordered a replacement of the same kind when I got home and made sure to cinch it down hard.

The front pistol iron sight I had epoxied onto the MAWL had been ripped off the laser at some point while at the DARC TUSC class; I assume it had happened during the vehicle drills segment of the class, but I don’t know for sure. Two months before that happened though, I did try to shoot with it in BUIS fashion to see if theory and reality intersected and if it was a viable modification.

Long story short, it’s not. One day at the range I was the last guy on the firing line during the last live fire of the day before the place closed, and I had to walk within 15-20 meters of the target just to get my hits visible on paper; at 50 I didn’t know what the fuck was going on. Once I figured out the offset and got back to the bench, I ended up having to aim like three feet to the right of my target to start getting hits on it. The image below is what my target looked like after shooting from 50 the very first time:

Some quick maths with the gang at B.E. Meyers suggested, once taking the location of the surface the iron sight was epoxied to relative to the emitters and bore into consideration, relative to the distance from the shooter’s eye, relative to the distance to the target, that the iron sight would have to be placed about a half inch to the right of where it’s placed currently. The next image is what my target looked like when I walked up and was 15-20 meters from the target with a dramatic rightward windage hold:

The problem is there really isn’t a half inch of space on that surface of the MAWL to move it, which locks the thing solely into its intended role as ONLY a visual reference under NV to tell me when to stop canting the gun and have the MAWL’s emitters directly over the bore.

In theory, a reshaped front sight that was perhaps made thinner than the one that was on there could give it enough space to move it over enough to also function as an emergency BUIS, along with carefully placing it upon applying epoxy. But honestly, it was never meant for that, so although it’s possible I’m not likely to pursue it; maybe BE Meyers will engineer a new rubber gasket with such a thing molded into it, or not. Who knows?

It also wasn’t very visible under night vision in the sense of serving as a visual index point for where to stop rotating the rifle so that the laser emitters were concentric over the bore at 1200. It was visible, but blurry and therefore easy to lose without focus, and didn’t throw back any ambient light through the fiber optic rod that made it stand out and more easily detectable.

CONCLUSION

Like I said in the beginning, this range report took way longer than it should have to get written; it was originally supposed to be “Hey I zeroed the rifle and here were my findings,” documenting the experience of one range trip. However, due to the diagnostic side quest with the SCO-15 lower and all the other traveling I did, this article now summarizes the experience of 10-12 range trips all together, indoor and outdoor alike. As it sits currently it does everything I expect of it, repeatedly and reliably.

Hopefully the others out there experiencing the same issues I did with the SCO-15 lower will find utility in this toward solving their own problems with it, but I must stress this much: You’ve gotta actually contact SilencerCo and let them know what’s going on! Otherwise they’ll assume that everything is as it ought to be, save for a few outliers, and it’ll be overlooked. They need to see numbers that, when weighed against the number of lowers produced/in circulation, illustrate a design flaw that manifests more commonly than uncommonly.

That’s all I’ve got. More to come on other topics.

Stay Dangerous.

Stay in this L.A.N.E.