When it comes to accurising M14 rifles, I've BTDT a few times ... or more.
Executive summary ...
for maximum return with minimum investment,
get a GI fiberglass stock, a trigger job, maybe a GI bolt, a GI op rod spring, a roundish op rod spring guide, and beat the snot out of your gas assembly splines instead of wasting money for shims and unitising. If you want a scope, expect to pay almost as much for the mount as you did for the rifle. If you want to stick with iron sights, get the US GI rear replacements [ either Garand or 14 ].
Anything other than that is [ on average ] going past the point of diminishing returns ... eg: you spend LOTS more money, and get VERY little in return..
As an example,
I just took two near new Norinco M-14s out to the range this afternoon to function test and sight in. Both had headspace @ .009" over 7.62 NATO GO.
With SA 7.62 NATO ball, I was getting about 3" groups.
HO ... HUM! Even after I mounted a 10X scope, groups were about the same.
Then I tried some Winchester Ranger 168 gr HPBT match ammo [ ex-RCMP LEO sniper issue ammo ] .
With the iron sighted 14, groups went down to about 2 1/2" ... HO HUM!! With my 4X scoped Rem 600, groups were 1 1/2" ... OK but not great.
BUT,
with the other/10X scoped 14, WHOOPEE!!
I shot 4 rounds into 1/2", .
Fifth shot was a flier pulled out to 2". Flier could have been the VERY heavy/creepy trigger??
I've noticed this before ...
some individual M14 rifles [ Chinese/Springfield or genuine US GI ] may have VERY dramatic ammunition preferences. With some 14s, some lots of BALL ammo can give you near match performance.
Before spending BIG bucks on all sorts of tweaks and tricks to make your 14 shoot better, I suggest you buy many Many MANY different brands of ammunition, and try them all under controlled conditions.
On average, through dozens of different 14s, my experience has been that Hirtenberger 7.62 NATO ball seems to be the BALL ammo of choice for many 14s.
For 168 GR HPBT match, the Winchester Ranger [ boxes marked for LE use only ] seem to be the load many 14s prefer.
Of course, I am speaking here of AVERAGES ...
through MANY different M14 rifles [ and by MANY I mean I've personally owned over three dozen genuine US GI 14s, about the same in Chinee 14s, and about half a dozen Sproingfield M1As ].
However,
all my experience isn't worth a fart in the wind compared to YOUR experience with YOUR rifle. Your individual rifle might prefer something entirely different ....
only way to find out is to spend small money on test ammo BEFORE you spend BIG money on "accurising"
And once you find what ammo your 14 prefers, buy lots more of that ammo BEFORE you spend money on tweaking and accessories
[ NOTE: for anyone who doesn't want to take my advice, I've got a $ 1000 JAE 100 stock for sale ]
as with any other advice you get FREE off the internet,
remember,
YMMV,
LAZ 1
[;{)
PS: for anyone shooting the old OLD Lake City Match ammunition, this ammo has a TAR type sealant around the bullets. Unfortunately, this ammo is getting on in years [ as am I ] and some of the tar some of the time has dried up. Which means this ammo can have erattic draw, which can mean vertical stringing. To cut group sizes down, simply seat all the bullets a couple of thou deeper. This cracks the sealant for all the bullets, and will give more consistent draw= more consistent velocities = more consistent groups.
just cause the adivice is free, don't mean it is worthless.
[;{)