I think my head is going to explode............(updated, sort of, post 32)

[Stevo]

I've been fighting with my Norinco M14 for the last year and a half.

My first issue was with a Troy Battlerail that when installed caused the rifle to short stroke and fail to feed. I never managed to resolve that problem. The rifle is now wearing a Vltor stock and Vltor M14 rail. It runs now, but the accuracy is, to say the least, terrible. I'm getting 6-8 inch "groups" at 100m regardless of the ammo used. I've read lots of posts all over the web and I don't even know where to start.

Lots of the info mentions checking for fit in various areas, like stock to stock ferrule, etc, but I can't find any that mention how the parts actually should fit. Clearly, I don't have the background knowledge that I need to understand what I'm reading.

The gas cylinder is shimmed properly. It gets snug at about 4 o'clock and tight at 6. The rail is tight and straight. The scope and rings are tight.

I'm not looking for match accuracy. Service level groups would be just fine by me. If anyone can point me in the direction of useful information or help out here, I would be very appreciative. My brain is getting quite bruised from all the banging into the brick wall.

Thanks,
Steve

The offending rifle:

Norinco M14S shortened to 18.5", Vltor stock and rail, Bushnell 6500 1.25-8x in Leupold rings, match op-rod spring guide and USGI spring.

Information

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[vintage hunter]

I have absolutely no experience with the ''modernized'' versions but these may be a few areas to check. The barrel was cut down to 18.5'', right? Was it threaded straight afterward? Bullets brushing the thingy on the end of the barrel maybe.
Does the rail touch the stock anywhere? It shouldn't AFAIK.
It's my understanding that the ferrule is supposed to put slight up pressure on the stock tip when the TG is locked up. BTW, how does the TG lock up? Some force required to close it or does it close easy?

[jmoore]

For unknown reasons, the last M1A on which I installed an 18" barrel refused to shoot as well. Horrible accuracy. But both of the random 22" barrels have been OK both before and after the 18" bbl install. On the other hand, a SAGE stock equipped 18" standard SAInc. rifle has been very, very accurate.

As far as front band fit, it needs to make no contact on it's rear face with the front of the stock. It also needs to have ~3-5 lbs tension between the lip and the bottom of the stock and be well centered. The handguard should not touch the stock. The triggerguard should take some force to close. There's lots more, but those are good starting points.

[jmoore]

Have you investigated the Blackfeather stock, yet? Seems like a good system.

[Patrick Chadwick]

The rifle is now wearing a Vltor stock and Vltor M14 rail.

That is, I think, part of the problem. A rifle should not "wear" anything. It is not a tailor's dummy. And the "clothes" affect the barrel dynamics.

Now for Grandpa's fundamentalist point of view:

Get rid of the plastic flimflam, ground-tracking radar, satellite telephone, automated teamaking facilities and whatever else is hanging on that long-suffering barrel and turn it back into the original GI configuration as far as you can.

Then try it out with ammo that is also as close to GI ammo as you can get or reload.
You may be positively surprised.

Some of these fully tricked-out modern rifles remind me of the Starfighters that were bought by the Germans way back heaven knows when. They were offered in various options: high-level interceptor, ground attack bomber, long-distance reconnaissance etc. etc. And the Germans said "Yes" to everything. In one model. The result was a flying emporium of all possible functions that crashed notoriously frequently, sometimes because the pilot pressed the wrong button and ejected himself. On one occasion while the plane was upside down, doing a roll over the runway at an air show. Hammered into the tarmac at several hundred mph, there was not much pilot left to bury.

Seriously, I think your barrel is suffering from bad vibrations. Get back to basics and start from scratch. If you can't find specific info for the M14, I imagine that the tweaking tips for the Garand will illustrate the principles quite adequately.

[jmoore]

Garands are easier in most respects to tune than the M14. But Patrick is right about the barrel harmonics thing. Try it without that big rail thing on top. No handguard at all, if it suits you. It is likely crashing into the forestock during the firing sequence.


The old carbon fiber stocked rifle that is currently just under 8 lbs (with handguard) without optic.

I don't know if this link that goes into some detail of the experiments will work, as the blog is no more on the current internet:

http://web.archive.org/web/201203032...tes-page3.html

[Stevo]

Thanks for the tips regarding handguard and stock fit. I should be able to take a look at them tomorrow.

- The crown is perfect and threaded straight. No bullet strikes on the flash suppressor.
- Regarding "modern flim flam". The stock is a modded USGI, nothing new there. This rifle is useless to me without an optic as my eyes are not getting more suitable to longer range shooting as I get older. I've already tried an ARMS 18 scope mount but the reciever side geometry on this rifle means it required extensive fitting. I wouldn't be surprised if harmonics were the issue, but Vltor has a very good reputation so I won't chuck the rail in the garbage just yet.
- The trigger group requires a moderate level of force to lock and open.

I'm not interested in the Blackfeather at all. I really don't like the way they do business.

Thanks to all, I'll report my finding as soon as I can.

[jmoore]

regarding handguard and stock fit.

One easy test: Grab the forestock and handguard just behind the front band and attempt to squeeze the top and bottom towards each other. The stock should be able to move freely upwards (under pressure) at least 0.030" or so. It's also a good thing to have some side clearance so that the stock can move a bit R&L. Mostly because the barrel whips about in sort of a star shaped (very rough analogy) pattern under recoil. Check for rub marks all about the front end if you've fired it a fair amount. The only rubbing should be on the top of front band lip and bottom of the stock ferrule.

Hey, Patrick: Here's a real pretty test bed for you!:


Flayed and sliced JAE stock. (Good bedding system, including a vertically adjustable front band tensioner, but obviously not a favorite assembly...) Note the "bad" handguard contact, though- so it was removed after the photo.


OH! ETA: Check your scope! These rifles have a reputation for destroying optics. One lower cost solution is to use optics made for spring powered air rifles.

[browningautorifle]

Some of these fully tricked-out modern rifles remind me of the Starfighters that were bought by the Germans way back heaven knows when. They were offered in various options: high-level interceptor, ground attack bomber, long-distance reconnaissance etc. etc. And the Germans said "Yes" to everything. In one model. The result was a flying emporium of all possible functions that crashed notoriously frequently, sometimes because the pilot pressed the wrong button and ejected himself. On one occasion while the plane was upside down, doing a roll over the runway at an air show. Hammered into the tarmac at several hundred mph, there was not much pilot left to bury.

I remember that...so, THAT'S what happened! Always wondered why they had so many problems.

[jmoore]

F104s also had bottom eject! That's one reason that they would invert at low altitude... I seem to think the design was later changed, but that bit of info has wandered out of the old brainpan- mostly because it's not propeller driven, nor WWII or earlier.