[kiwigrunt]

Hi team. I recently added a suppressor to my m14 so I dont deafen my dogs and it has caused a few issues. Before adding it I had not had a stoppage but now every5-7 rounds I get one. They are caused by the round not ejecting properly. My guess is that the supressor has messed with the back preassure that works the gas piston.

I spoke to a smith who was not much help so thought I would try here. Has anyone had the same and knows of a solution.

 

[tonyben]

Does your rifle have a scope?

The increased pressures should be speeding up the action but if it's speeding up the action, I wonder if your extractor spring is weak and not pulling out the round as good as it should be. How is the blowback in your face? I've only shot a suppressed M14 once and it was not a pleasant experience.

What kind of M14 is it? Is it a real M14, being that you're in NZ?

Tony.

 

[TheDudeAbides1970]

You may just need an brownell's adjustable gas plug with the suppressor, see this vid,[ame]http://youtu.be/rYMoOXNzvmA[/ame]

 

[kiwigrunt]

Does your rifle have a scope?

The increased pressures should be speeding up the action but if it's speeding up the action, I wonder if your extractor spring is weak and not pulling out the round as good as it should be. How is the blowback in your face? I've only shot a suppressed M14 once and it was not a pleasant experience.

What kind of M14 is it? Is it a real M14, being that you're in NZ?

Tony.

Its a norinco copy, not the authentic thing.

Yes it has a scope. There are a few dings on the scope mount. Will put some spotting paint on it and see if its impacting there. Had not thought of that.

Is there a way to check the extractor spring myself?

Had no issues with blowback.

 

[tonyben]

Okay. It's ALWAYS going to hit the scope mount on the way out. I think you just have to make an adjustment on how it ejects the round. Try cutting off 2 coils from the ejector spring, or get a new ejector spring and see if it helps. If it gets worse after cutting the spring coils, the cost of a replacement spring is very cheap.

Also, if you have a nut/bolt style scope ring, make sure the side that you tighten is on the left side of the receiver. If its on the right side, flip the scope rings around so that they are on the left side. This will give you more clearance.

Also, please post some pictures so we can see if there's anything else that stands out.

Tony.

 

[Dave P]

So I am anxiously awaiting my 30 cal suppressor - signed the final papers last Thanksgiving.

One of the first uses will be on a full size M-14. Scoped, I suppose.

Should I anticipate any extraction issues with a std gas plug? Would reduced loads help the blowback concerns - or would they increase the FTE occurrences??

 

[tonyben]

Scoped or not, Dave? I don't think extraction is the issue; it's where the extracted case flies, that's the issue. Venting the gas system with either a vented piston or plug will change action cycle speed and the placement of the extracted case. You may have to tune your system by venting, cutting ejector coils or hand loading lighter loads, or all three, to get it to cycle right.

If using irons, you need something to contain the blowback, like a blank firing adapter, and maybe, to a certain degree, the same using a scoped rifle.

Tony.

 

[kiwigrunt]

Okay. It's ALWAYS going to hit the scope mount on the way out. I think you just have to make an adjustment on how it ejects the round. Try cutting off 2 coils from the ejector spring, or get a new ejector spring and see if it helps. If it gets worse after cutting the spring coils, the cost of a replacement spring is very cheap.

Tony.

Have cut off two coils and will test fire it next week. Will put picts up if that does not fix it.

 

[kiwigrunt]

Finally test fired it. Had less stoppages; better, but still not perfect.

Have added a couple of pictures replicating what the stoppages looked like. In the past the round was facing straight up/down and resolving the stoppage was far more work. This time they were as shown.

In my mind removing the some of the spring helped and its no longer ejecting straight up. Would removing 1-2 more coils help? I also put a red circle around a part of the scope mount that I am thinking I will grind back as its where the stoppages seem to be getting hung up.

Thoughts?

 

[2Sharp]

Are the next cartridge from the magazine still in the correct position in the magazine when the malfunctions occur? Or is it partly fed into the chamber?

 

[kiwigrunt]

Are the next cartridge from the magazine still in the correct position in the magazine when the malfunctions occur? Or is it partly fed into the chamber?

partially fed into the chamber.

 

[2Sharp]

Ok, this have been bounching around in my head and I have an idea...

I have never heard or experienced a suppressed weapon that suffers from decreased backpressure, so I have the idea that as the suppressor increases back pressure the mechanism in travelling faster and maybe, just maybe it travels so fast backwards that it actually bounches at the back of the receiver* and back forward again, before the empty casing have the time to eject.
As we know the next cartridge is being partially fed into the chamber the bolt has travelled back far enough to pick it up, so it isn't short stroking.

I would suggest changing the ejector spring and ejector and also the extractor and extractor spring rather then shorten the ejector spring.
And by changing the ejector itself you make sure that it's angled surfaces are properly ground and as they should be. Same goes for the extractor and it's spring and plunger.
I would also look into a new operating spring and an adjustable gas plug.

My .3 cents... HTH

*or close to it, maybe maximum compression of the operating spring? Keyword is mechanism bounce!

 

[kiwigrunt]

Ok, this have been bounching around in my head and I have an idea...

I have never heard or experienced a suppressed weapon that suffers from decreased backpressure, so I have the idea that as the suppressor increases back pressure the mechanism in travelling faster and maybe, just maybe it travels so fast backwards that it actually bounches at the back of the receiver* and back forward again, before the empty casing have the time to eject.
As we know the next cartridge is being partially fed into the chamber the bolt has travelled back far enough to pick it up, so it isn't short stroking.

I would suggest changing the ejector spring and ejector and also the extractor and extractor spring rather then shorten the ejector spring.
And by changing the ejector itself you make sure that it's angled surfaces are properly ground and as they should be. Same goes for the extractor and it's spring and plunger.
I would also look into a new operating spring and an adjustable gas plug.

My .3 cents... HTH

*or close to it, maybe maximum compression of the operating spring? Keyword is mechanism bounce!

Thanks,

Will try grinding back the part on the scope mount where it keeps getting caught up. It may simply be that. If that does not work I will start replacing a few parts.

Will keep everyone posted in case someone else has the same issue down the track.

 

[tonyben]

What kind of scope mount is it? I'm wondering if it needs an angled cut to allow the brass to deflect. I also agree, you may need a vented gas piston or an adjustable gas plug. You can try cutting of a couple of more coils and see if that changes anything.

Tony.

 

[cockednlocked]

You may just need an brownell's adjustable gas plug with the suppressor,

This is what I would do, too

..... Venting the gas system with either a vented piston or plug will change action cycle speed and the placement of the extracted case. You may have to tune your system by venting, cutting ejector coils or hand loading lighter loads, or all three, to get it to cycle right.

Right. The suppressor effectively lengthens the barrel, and thus dwell time, so more gas is available for cycling. I'm more familiar with the effects on a gas impingement system like an AR, but the same thing happens: with a suppressor you suddenly have an excess of gas, which changes the cycling speed. You have to bleed the extra gas somehow, or make less gas by reducing the powder loads for your suppressed rounds. Venting the extra gas allows you to keep the higher velocity for improved ballistic performance, unless you want to download for subsonics. With the AR, you also have the option of changing buffer weight to alter the reciprocating mass, but not on the M14.

....... so I have the idea that as the suppressor increases back pressure the mechanism in travelling faster and maybe, just maybe it travels so fast backwards that it actually bounches at the back of the receiver* and back forward again, before the empty casing have the time to eject.
As we know the next cartridge is being partially fed into the chamber the bolt has travelled back far enough to pick it up, so it isn't short stroking.

This can't be good for the bolt or the back of the receiver.

Just curious, have you measured the difference in sound level with the suppressor vs without it? I think it would be cool to work up some subsonic loads for the M14. My cousin is messing with that thought on a .308 bolt gun; he's using Trail Boss because it is so bulky for its weight.

 

[kiwigrunt]

What kind of scope mount is it? I'm wondering if it needs an angled cut to allow the brass to deflect. I also agree, you may need a vented gas piston or an adjustable gas plug. You can try cutting of a couple of more coils and see if that changes anything.

Tony.

Its not this exact one but very similar. http://www.guncity.com/aim-sports-m14-m1a-side-scope-mount-xidp247412.html

Where it gets hung is is on the same place. Initially the stoppages were crazy but after removing the 2 coils off the spring it seems that the stoppages are because the round is getting caught on the mount. I think it had 2 problems; that the round was ejecting at a stupid angle and that the scope mount was deflecting/catching the case as it was being ejected. I will grind it back so there is no obstructions on the scope tomorrow and test fire again. If that does not fix it then I will need to buy some hardware as suggested.

@cockednlocked and @2sharp, I put some spotting paint in there when I last test fired it and there was nothing that lead me to believe that the bolt was bouncing of the back of the receiver.

The suppressor does make a sizable difference. It brings the volume down to quieter than a 7.62x39 but louder than a .222. II can tell the difference with and without ear protection. Its worth it for what I use the rifle for.

 

[tonyben]

Can you order stuff through Brownell's? If so, and if nothing else works, consider a Sadlak scope mount. But for the health of the rifle, I think you should get the vented piston or plug anyways.

My money is on cutting coils and using an adjustable gas plug.

Tony.

 

[kiwigrunt]

So removing another coil and grinding back the part of the scope mount that the round was getting caught up on has done the trick. The adjustable gas plug has been put on my soon to buy list.

Thanks everyone for your advice in fixing this issue.

 

[2Sharp]

Great to hear that you got it resolved!! Happy shooting

 

[tonyben]

Excellent! Great to hear!


Tony.