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Posted: 6/12/2014 3:17:16 AM EDT
Anyone using these with imr4895 in a M1a? I am at near 43 gr in test loads and cannOt get consistent cycling.
Thoughts?
Link Posted: 6/12/2014 4:23:08 AM EDT
I've used lots of IMR 4895 and 147 grain M80 pulls in .308 loads for my M1A. It's just about perfect for that application. What is the cycling problem?
Link Posted: 6/12/2014 9:25:59 AM EDT
First make sure the gas piston isn't for heavy bullet match loads and check the gas plug for tightness.

Make sure the spindle valve is set correctly.

The most common cycling problem with the M14 is undersized cases.

The cases may be sizing too small.

Check case length and make sure the length isn't too long.

Link Posted: 6/12/2014 3:50:38 PM EDT
Thanks for the replies. To the poster two above, what weight charge for the imr 4895 do you use?

to the poster above, tell me more above the issues of under sized cases?
Link Posted: 6/12/2014 6:29:34 PM EDT
[Last Edit: 6/12/2014 6:34:59 PM EDT by BroadSideOfADime]
I've been running 42gr of IMR4895 in LC brass topped with Hornady 150gr FMJs with Winchester or S&B LR primers.

No chrono data but was accurate enough for me considering I'm not an expert with iron sights.

Doesn't seem to be terribly harsh on the brass too. Fired in an M1A Scout.

ETA: Looking at my notes, I started my ladder at 41gr of IMR4895.

No cycling problems at 41gr and 41.5gr in my rifle.
Link Posted: 6/13/2014 4:48:24 AM EDT
[Last Edit: 6/13/2014 4:48:47 AM EDT by Troepie]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By skink:
Thanks for the replies. To the poster two above, what weight charge for the imr 4895 do you use?

to the poster above, tell me more above the issues of under sized cases?
View Quote


If the case shoulder is pushed back too far, it can cause cycling problems, especially in the M14.
Link Posted: 6/14/2014 6:15:49 AM EDT
I have some once fired brass that was commercially resized. I will give it a try.
Link Posted: 6/14/2014 6:31:28 AM EDT
[Last Edit: 6/14/2014 6:41:44 AM EDT by SteelonSteel]
What is your rifle's failure stoppage? Your inconsistency description is a bit vague.

IMR4895 is just about perfect for the rifle, in that rifle I use IMR4895, H4895 or IMR4064 exclusively with 150ish fmj's, 168 noslers, and occasionally 155 noslers.

I use 41 grains of IMR4895 with both the 150s and the 168's.

Somethings to check;
-rifle lubed per the manual with grease on the sliding surfaces, bolt raceway, op rod spring, op rod/barrel contact and a dry gas cylinder and piston
-good quality magazine, there are plenty of chinese clone mags that will cause stoppages due to improper spring bends, crappy followers
-obviously if you have any cycling of the bolt when fired it's not the gas cylinder cut off.
-do make sure your barrel port isn't partially blocked by the gas cylinder being screwed down too far or too little. (unlikely but possible, IIRC most gas cylider ports are generous and more open than the barrel port, take the plug out and bend a wire or paper clip and make sure you can pass it through from the gas cyclinder to the bore)

if it runs with good surplus then it's unlikely a gun/magazine issue. Do test with known ammo to help diagnose.

loading for the M14, read this http://www.zediker.com/downloads/m14.html

he has a quirky writing style (i like it but many don't) but his experience with the m14 is sound. He may sound the alarm a bit to hard but his explanations bear reading. You really should know the headspace on your rifle and the final headspace on the rounds you make. He'll explain why.


ETA- I will politely disagree with the poster that said shoulders pushed back too far will cause cycling issues. Too small and they will fire and cycle but read on and I'll explain a bit on that. If extremely short you will can get a failure to fire as the case isn't supported for the firing pin hit. More dangerous is that you can get a case rupture and a case head torn off. If you have the equipment you will find that factory ammo is smaller in dimension than what most dies can accomplish. Of course it's only like that once and that's all the factory has to consider. Any reloads the liability is on you. They do that because they have no idea what gun it will go in so for them it must chamber every time.


ETA2 - also check your fired brass and your chamber, Is your chamber roughly cut, lots of tool marks? SAInc does a fair amount of that. A really rough chamber will imprint those imperfections on the brass and make extraction more difficult sometimes inducing a failure to extract stoppage.

Many new M1 and M1a shooters will have cycling failures due to improperly lubed rifles. Check that first.
Link Posted: 6/14/2014 7:17:00 AM EDT
I have some once fired brass that was commercially resized. I will give it a try.
Link Posted: 6/14/2014 9:47:45 AM EDT
Well I never got your answer on what kind of stoppage you have and I am about to go off to work.

Empty brass staying in the chamber? ie failure to unlock/extract?
Empty brass caught in the cycling of the next round; failure to eject?
Failure of next round to chamber, bolt caught on the round still in the feed lips?
Failure of bolt to go back far enough to pick up the next round?

With 43 grains I'd say you've got plenty of power, in fact I'd almost venture to say too much. Did 40, 40.5, 41, 41.5, 42 and 42.5 grain charges cycle better? worse? same?

answer some of these Q's and a lot of guys here can direct you where to look at fixing.
Link Posted: 6/14/2014 3:12:08 PM EDT
[Last Edit: 6/15/2014 6:14:48 AM EDT by skink]
Sorry, arfcom locked up on me and I double tapped and didn't see your post. Gun is clean, but I have not taken the gas system apart, I just got the wrench for it.

The failure I have is only for reloads, factory functions fine. I have fired about 400 rounds of factory with no issue.
The failure is FTE. The rifle fires, but the bolt does not move, but it doesn't happen all the time. On a 5 shot string, one to three of the shots will not cycle the bolt.
I shot 5 factOry PPU while testing and they fired fine.

Edit: this was from 41.0gr to 43.0gr of imr 4895. All had failure to eject.
Link Posted: 6/15/2014 12:16:31 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By skink:
Sorry, arfcom locked up on me and I double tapped and didn't see your post. Gun is clean, but I have not taken the gas system apart, I just got the wrench for it.

The failure I have is only for reloads, factory functions fine. I have fired about 400 rounds of factory with no issue.
The failure is FTE. The rifle fires, but the bolt does not move, but it doesn't happen all the time. On a 5 shot string, one to three of the shots will not cycle the bolt.
I shot 5 factOry PPU while testing and they fired fine.

Edit: this was from 41.0gr to 43.0gr of imr 4895. All had failure to eject.
View Quote


Those loads should be fine.

I've been loading for the M14 for 30 years.

I haven't had problems but I seen at the range problems that were caused by some case sizing issues.
Link Posted: 6/15/2014 3:36:05 PM EDT
Were the problems similar to my issues?
Link Posted: 6/15/2014 6:17:03 PM EDT
[Last Edit: 6/15/2014 6:21:47 PM EDT by SteelonSteel]
ok, got ya, a failure to extract. The powder weight should be plenty to cycle. When everything is in order you can drop to 38 grains or so and still get cycling in a normal M1a setup.


When you get your wrench, pull your gas plug and pop out the piston. Check with a bent wire that your ports are in line and not partially occluded. Like was said already someone at some time may have dropped in a match piston for hot loads, they have a longitudinal slot in them a usgi one doesn't have to relieve the extra gas. May as well give it a look while it's out. I am not thinking it's this, if your PPU is loaded equivalent to LC ball then it should also cyle. Your load is an approximation of LC ball ammo.

FYI, a standard wrench will fit the gas plug, can't remember which one, 3/8, or 1/2 inch. Also if you got the usgi cleaning kit with it, that goofy handle has the correct wrench in it. Gently clamping the gas cylinder in between two pieces of wood in a home vise and a standard wrench is a fine method of take down. Doing this saves the rotational wear on the barrel splines. Good tight spline fit is a good thing for accuracy.

Your gun is clean, chamber spotless too, now would be a good time to do a field strip, pop the action out, take off the op rod and spring. Ever strip your bolt of it's firing pin, ejector, and extractor? I would do that and take one of the suspect LC loaded cartridges and an empty LC case that you processed the same as the problem loads. With the stripped bolt in the gun, insert the round into the chamber and with your fingers close the bolt on it. The right lug with the roller on it should drop right down onto the notch with a clunk. You shouldn't have any drag on the bolt binding on the brass. Check a handful and see if any drag. If you feel drag you don't have your cases sized enough to give you 0.002-0.004" headspace. Try closing the bolt with no brass in the chamber, that's pretty much what you want to feel. It's not a bolt gun so it needs the headspace. You don't want an excessive amount either, that sets up for case head seperations. While case head seperations aren't good, they're notusually tragic like an overloaded round that lets loose and blows chunks off the bolt. They'll jam up your gun with the front half of the brass stuck up there and you could gas torch marks in your chamber with a bunch. Best avoided by setting up your dies well to match your rifle. If you read that link I posted you already know what I'm blathering about. Setting up your dies to cam over might be far too much for an m1a. I know when I was learning I did just that and was getting partial case head separations.

Double check your brass OAL and your neck diameter on that brass with a bullet seated and compare to the manual. The neck needs a bit of room for the neck to expand and release the bullet.

Link Posted: 6/18/2014 2:48:01 PM EDT
Thanks for the detailed writeup. Will clean the gas system and see if that helps.
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