I hate the internet.
There are days when I think I should cancel my internet and use the money to go shooting instead.
I felt the exact same way yesterday.
Thanks for everyone’s replies.
I used to lap the receiver face, etc. Then, a well distinguished high power shooter said that either the USMC or AMU stopped the practice as they saw no real benefit to the practice.
He shoots better in his feet than I do in the prone.
ETA: stupid phone submitted my post before I was done typing.
Parts have gotten better, if you buy good parts. In the last ten rifles I’ve assembled using DD, BCM, and a couple ARP 6.8 barrels. All using Aero uppers, I have pretty much had to resort to a plastic mallet to get the barrels into the uppers. No shim stock is going to fit in there, and I don’t really see any need to loctite them either. I also seriously doubt that I could much improve on the barrel’s grouping through gunsmithing. I see far better results from proper load development. All of which is a waster of time if you can’t make a good wind call, or don’t have good shooting fundamentals.
Use a hair drier or a heat gun on those tight uppers to get the barrel in.
Why???
Best advice given.
Expands the receiver just enough to accept the barrel extension and when it cools it will tighten up on it. This of course only if the receiver is a tight fit/oversized barrel extension.
Scroll through for science post:
https://diy.stackexchange.com/questions/90392/if-metal-expands-when-heated-how-does-heating-a-bolt-loosen-it
In my experience chasing tiny groups there are measurable gains in accuracy and there are theoretical gains in accuracy. A match barrel and trigger will result in measurable gains in accuracy, All the other voodoo is theoretical. For example if we took a stock M4 and swapped out the barrel with a Krieger it would shoot measurably better. If you took the same M4 and did nothing but swap the receiver for a thicker MUR would it shoot measurably better?
Grant’s recipe for success;
*NOTE, assumptions are made that the builder will be using KNOWN, QUALITY barrels, receivers, etc.
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Tight fit between barrel extension and receiver.
A. You can use loctite, but assume that if Green is used, you probably won’t get it back apart.
B. Just use a BCM or VLTOR receiver as they specifically undersized the barrel extension hole (tight fit). -
Check that the upper receiver M1913 rails are square and true.
A. We use a Tru-Stone from Starrett to verify. -
Barrel nut is at or under 40lbs.
A. You can use shims if the barrel nut design doesn’t allow for correct timing at that poundage. -
FH/MB is timed (5 O’Clock position) so as not to put to much pressure on the end of the barrel (which causes “trumpeting”).
A. Use shims to time. -
Fit bolt to barrel extension. J. Noveske taught me this (along with ranges for each barrel length and gave me the gauges he had made).
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Square and true the barrel and then re-crown (30 degree).
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Be a good shooter! Use a good trigger! Use good ammo! Use good glass! Well, Duh!
C4
That’s a whole lotta work for basically nothing gained over a properly built AR with high quality parts like the barrel. I’ve extensively evaluated a DD, LMT, Sionics, KAC, BCM, Colt, and several others. All of those barrels will be around 1-1.25MOA using true 10rd groups (if we were doing three 5rd groups like the article, then these barrels would print around .75 MOA with exceptional trigger control, and shooting technique given you add three things imho…
If you want “turn key” accuracy potential out of any, and every quality AR made (lets assume the barrel is FF)…it only requires three things:
NF Compact optic 2.5-10x models (fill in your 2/3-9/10x variable powered optic)
Geissele 2stage trigger…SD-E is my pick (A KAC 2 stage will work fine, but a G trigger will give complete control on the second stage wall)
Atlas V8 (or updated) bipod … In prone position, with a slight load…this bipod is truly a game changer…or was when it came out and hadn’t been copied by everyone. Out of the knockoffs, the KAC seems to be the next best option imo. Even a Harris BRMS will do fine, especially if you upgrade the tilt/cant knob.
Obviously we’re using ammo as a control…but if not, three loads will usually tap an ARs potential out given the Indian is present…
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Hornady 55gr. Vmax. IMHO the finest factory ammo to shoot 10rd half dollar groups out at 100yds. Honestly never seen an AR that didn’t absolutely love this loading. Sure it’s a paper tiger terminal ballistic wise, but damn if it’s not bughole accurate.
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Hornady 5.56 TAP T2 75gr. For ranges past several hundred yards. Don’t waste this stuff unless its at distance, and you really require extreme accuracy as it’s rare, and costly.
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BH red box 5.56 77gr. OTM SMK ( MK262 ) For max effective range accuracy…if you gotta fly to 1000 and buck transonic, this is the round for the job.
Examples…
My HD rifle sits 99% of the time like this ready for the boogie man…A DD 14.5" LW pencil barrel/BCM FA BCG with BCM CH/Geissele proto MK1 13"/KAC micros/T-1
(absolutely no voodoo or secret sauce was applied…as in no “accurizing” besides building it from scratch according to military type specs, I.E. torque values, staking nuts, using the right grease on barrel threads, etc.
Now here is same rifle pushing the absolute envelope of it’s accuracy performance with the turn key items added. At a bit less than 750yds, it recorded a true 10rd group measuring 1.1 MOA IIrc. Note only things added are the turn key pieces of kit minus the bipod ( attach it once at the range)…NXSc 2.5-10x24 Geissele SD-E Atlas bipod & TAP T2 ammo in that vid
Group from vid
Can you provide more info on this process?
I always enjoy reading your posts. That’s some great shooting, and a really nice rifle.
Thanks for taking the time to post.
It’s my pleasure friend, and I always appreciate your words of encouragement.
Photobucket ruined so much of my threads on here that I haven’t really been active posting wise, however now that I found Imgur, and finally am getting to shoot quite frequently again…I hope to change that. My close by range had a oil and gas explosion that rocked all of central Alabama and closed the range for 6 months…some dude right by the range dug with a backhoe, and you can guess his fate.
I just got into M1 carbines the last cpl. months, and am so far down that rabbit hole its not even funny. I wish I could share more on those on M4C, but I’m not sure folks are into 70yr old carbines.
Sure. You take a bunch of bolts. Remove the ejector from them. Put the one of the gauges (for that barrel length) into the barrel. See if the bolt will lock. Repeat till you find one that does.
C4
I having been shooting M1 Carbines for several years and would be interested in your observations and tips if you started a thread.
What? Are you sticking a rod with a stop down the barrel?
Not Grant, but think what he meant was he was setting the minimum headspace by picking a bolt that would lock on a specific gauge in the chamber. The gauge mimics a chambered round, so no need for rod in barrel.
Mark
Bingo.
C4
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