So, Holescreek probably has the market cornered on this stuff, but I figured I'd throw my two cents in just for fun.
So over the years I've been gradually working on minor low- or no-cost improvements to my C308 to improve the overall fit and finish, as well as the performance of the firearm. Most of this stuff could be done with very basic hand tools, sandpaper, files, a wad of steel wool on the end of a pair of foreceps, or occasionally something a little more ambitious like a fine grinding stone on a Dremel.
Mostly this was an experiment to see if my understanding of what accuracy comes from gathered over the years translated into practical results.
The answer is a sweaty, wide-eyed, voice-cracking "YES".
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These two were taken at 100 yards on different trips using the same 168gr PPU "match grade" HPBT ammo. This gun is a sow. Both groups were taken with a *filthy* trunnion, barrel, chamber flutes, and bolt face, using ammo that is... Let's be honest, middling at best. It seems to like it better than the 175gr Federal stuff I was doing so well with earlier.
To clarify, no major structural or mechanical alterations have been made to this rifle. THe gun has its original pencil barrel, non free-floated, military surplus trunnion installed by the chimpanzees at Century Arms, and bolt gap on the low side of "In spec" after about 1,000 rounds.
Here's the short list so far.
-Honed inside of cocking tube with coarse steel wool on a set of hook nose forceps for smoother, quieter action. Mostly just for feel.
-Honed inside of receiver and used sandpaper to "lower" spots beneath scope rail welds where the bolt was rubbing to reduce shot to shot variance from friction.
-Ground down the rear of the trunnion to ride flush with the receiver rails in order to reduce or eliminate roller predeployment for more consistent lockup and less wear on structural parts.
-Replaced trigger with German unit because I like the way the sears work better for the purpose of polishing, adjusting, and cleaning.
-Replaced locking wedge with Holescreek's 40 degree wedge.
-Used Dremel wire wheel to "polish" the inside of the trunnion to increase consistency of roller engagement and release. Rechecked bolt gap. Satisfied with lack of change on the feeler gauge.
-Homemade cheek riser for ergonomics and to reduce parallax inconsistencies.
I recently had the notion that I wanted to have an actual bipod for additional stability, as well as a degree of flexibility in the field or in an emergency situation. The gun has been more reliable on a wider variety of different types of ammunition than my well kept and otherwise totally stock S&W M&P15, if you're wondering why this oddball firearm enters into the equation at all when "emergency" comes into question.
I opted for the custom ultralight M-lok foregrip from HKParts as it was advertised as compatible with the CETME.
That ended up being a load of crap. The grip is so short that after the first two shots the whole thing walks forward out of the trunnion and dangles loose from the barrel, requires substantial grinding to fit over the spacer rings behind the front sight post, and the M-lok holes are out of spec and required significant filing to fit any of my accessories. Given that HKParts deleted my review twice for the item, I'm not sure I'll be going back to them in the future unless completely necessary.
So given that there really aren't any other options for an aluminum M-lok foregrip beside the Midwest Industries unit that is advertised as incompatible with the CETME without significant modification for exactly the same reason I had trouble with this one, I ended up deciding to make it work in my own way.
So I designed a spacer.
It had to accomplish the task of securely pressing the grip back into the trunnion, reducing any directional play it possibly could, and putting as much pressure on the front sight block and cocking tube as possible in order to avoid introducing any new and unexpected harmonics to the whippy little pencil barrel. I ended up doing all this *and* making it significantly easier to repeatably install the thing after removal for inspection.
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The curved surface is designed to tension the mounting screw evenly without forcing it downward or putting too much stress on any one part of the threads. The little tapered "wings" force the back of the grip into the trunnion during insertion and provide enough front to back play with the locking bolt removed to uninstall the grip without any more force than I can apply with my bare hands.
The whole thing is *rigid* now. Planning to test it out today. I feel like removing the extra weirdness and play from the wooden foregrip will at the very least not hurt, but probably enable a slightly greater degree of accuracy. I am also hoping the airy ventilated aluminum grip will vastly improve barrel cooling and significantly increase the effective accurate rate of fire without having to wait for the barrel to cool as long between shots before it heats up enough for my grouping to start spreading out.
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I love the look of the wood. At some point I might make a nice, blond-colored wooden handgrip section that fits nice and close over the back end of that aluminum grip to preserve that aesthetic, but for the moment, my priority is balancing performance and weight. It's just convenient that the wooden stock with a homemade cheek riser weighed less than the Magpul PRS since it allowed me to keep the pretty wood mostly intact.
The accuracy is getting close to where I'd consider scientific testing of the different delay wedges likely to yield meaningful results. I still need to get a better feel for how barrel heat affects grouping size.
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