DMPS Mod A-150 7.62 X 39 Help

G

Goshinki

New member
I'm having a problem with it. I went out shooting twice and same thing happened both times. I would fire a shot or 2 and then it would strike the next round but no fire. I would then load the no fire in my ak-47 and boom fired it. I have no idea what is going on with it but any advise would be great. I will upload photos if needed but i must tell not much experience with ar-15s so please be specific on what photos you need. Or if you have skype video chat.
 
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First off: What type of ammo were you using?
If using European ammo, have you swapped the hammer spring to accommodate the harder primers? It's not surprising that the ammo fired when restruck in an AK-those are designed to pound a primer like a hammer and punch.
Is this 7.62 a "package" (upper with complete BCG-ready to pin and shoot or complete rifle)? In some cases, a longer "enhanced" firing pin is needed to ensure firing those steel case primers.

I carry an AR in 5.45x39 9 months a year and have found I get an occasional failure to fire when it gets dirty. Even with the correct firing pin and a heavier hammer spring, it doesn't take much debris to create a FTF condition.
 
What ammo? I assume cheap steel cased surplus?

Sounds like light primer strikes. Basically the firing pin doesn't have enough oomph to set off some of the harder primers. Or some of the primers are set really deep in the case and the firing pin is just a touch too short. Stronger hammer spring will likely fix the issue.

Edit: Mobuck beat me to it.
 
I use tula 7.62 x 39 in both my ar and ak which like you said the ak never fails except with wolf rounds and if it is the firing pin being to short to hit well enough what to a upgrade to?
 
get the heavier hammer spring. That cleared up the majority of my no-fires shooting steel 7.62AK through my AR.
A slightly longer firing pin (not by MGI) might solve that also.
 
You shouldn't need a new bolt-just the firing pin. It's also important to use the heavier hammer spring. With the heavier hammer spring you may find your trigger pull has become stiffer. I found it necessary to upgrade my entire fire control when using the heavier hammer spring to keep the trigger pull reasonable.
FWIW, I haven't had any real problems with the 7.62 versus what I've had with the 5.45. This may be because I don't use the 7.62 much in cold weather nor do I shoot the 7.62 nearly as much as the 5.45-law of averages says fewer shots= fewer opportunities to malfunction.
 
Mobuck
I found it necessary to upgrade my entire fire control
Click to expand...
I'd say that my trigger pull is heavier, but coming from a distant history of C&R experiences, I didn't find it unacceptable. Doesn't mean I'm right, probably I'km just not paying enough attention.

I'm curious, though, what changes did you make to the fire control group? Did you have the parts polished or swap parts?
 
This a brand new rifle? You clean it before shooting? If not, do so before you start spending money un-necessarily. If a bath doesn't fix it, call whoever built the thing. You should not have to fix it.
 
"what changes did you make to the fire control group? Did you have the parts polished or swap parts?" I mostly use ALG QMS fire control parts when needed. The heavier hammer spring raised the trigger pull into the 9# range but the QMS brought it back down to 5.5-6#.
I patently DO NOT RECOMMEND any polishing of AR fire control parts.
 
To T. O'Heir it is not a new rifle and the guy who i bought it from is in florida and it was like 7 years ago but yes i clean the guy everytime i use it
 
As everyone is saying, its most likely the hammer spring is too weak for the primers. I have a suggestion that will give you a better trigger pull and take care of the light primer strikes.

Velocity arms has a drop in trigger specifically for steel case ammo in ar 15s. They are a single stage trigger with a 4lb pull.

If you are interested my shop sells them $135 each.

Just shoot me an email at advancedfirearmsolutions@gmail.com
 
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