need help with 9mm ar

tommy gunn · Mar 19, 2016

j_h_smith said:
Just curious, what ammo were you using?

The first time I shot it was with 115grain winchester and it was a jam-o-matic. I wanted to try a higher grain the second time and I used 123 grain zqi. It was all I could find and that's when the whole exploding bullet thing happened.

j_h_smith · Mar 19, 2016

tommy gunn said:
The first time I shot it was with 115grain winchester and it was a jam-o-matic. I wanted to try a higher grain the second time and I used 123 grain zqi. It was all I could find and that's when the whole exploding bullet thing happened.

This is hot ammo. It's rated as a +P. Here is the warning on the ammo I have, is yours the same?

"To avoid serious injury/death to shooter and bystanders: Use only in modern 9mm firearms in good condition. These cartridges are loaded to military velocity and pressure which is higher than 9mm Luger cartridges: average pressure is 10% higher than industry standard pressure for 9mm Luger"

If somehow that round was double charged, this could possibly cause your failure. Since you don't have any locking lugs on your chamber, everything could have gone out the back of the cartridge.

Since your firearm didn't do this with the WWB 115gr ammo, I think I'd look at either headspacing or possibly really dangerous ammo. I really would look into the ammo first.

I'll do a search on the ammo and see if this is an issue.

Good Luck!

tommy gunn · Mar 19, 2016

j_h_smith said:
This is hot ammo. It's rated as a +P. Here is the warning on the ammo I have, is yours the same?

"To avoid serious injury/death to shooter and bystanders: Use only in modern 9mm firearms in good condition. These cartridges are loaded to military velocity and pressure which is higher than 9mm Luger cartridges: average pressure is 10% higher than industry standard pressure for 9mm Luger"

If somehow that round was double charged, this could possibly cause your failure. Since you don't have any locking lugs on your chamber, everything could have gone out the back of the cartridge.

Since your firearm didn't do this with the WWB 115gr ammo, I think I'd look at either headspacing or possibly really dangerous ammo. I really would look into the ammo first.

I'll do a search on the ammo and see if this is an issue.

Good Luck!

This is the only warning on the box other than keep out of the reach of children.

Sent from my SCH-S968C using Tapatalk

j_h_smith · Mar 19, 2016

Here on MDS is a discussion about the very ammo you used. I didn't read the entire thread, but looks like it could be really hot ammo. I did read where someone said this ammo was made for full auto firearms, like an Uzi.

http://www.mdshooters.com/showthread.php?t=159818&highlight=zqi+9mm+123gr

tommy gunn · Mar 19, 2016

Thank you clandestine and everyone else for all your help and assistance. It is very much appreciated.

clandestine · Mar 19, 2016

tommy gunn said:
Thank you clandestine and everyone else for all your help and assistance. It is very much appreciated.

I do agree about that ammo, its hot from the reports I have seen. I dont have first hand experience with it though. I would stop using it on a blowback gun and use it on a locked breach handgun.

mopar92 · Mar 19, 2016

ZQI is NATO spec ammo. It's loaded a bit higher than normal stuff. I'd only use it in something that has a locked breech like a quality handgun. On a blowback gun its no bueno.

tommy gunn · Mar 19, 2016

clandestine said:
I do agree about that ammo, its hot from the reports I have seen. I dont have first hand experience with it though. I would stop using it on a blowback gun and use it on a locked breach handgun.

If I switch over to the tubbs spring should I try a heavier buffer too or just the spring and try the buffer if the spring don't work?

clandestine · Mar 19, 2016

tommy gunn said:
If I switch over to the tubbs spring should I try a heavier buffer too or just the spring and try the buffer if the spring don't work?

Show me the side and the face of the buffer and I can give better advice on buffer needs.

tommy gunn · Mar 19, 2016

clandestine said:
Show me the side and the face of the buffer and I can give better advice on buffer needs.

I hope that is helpful.

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clandestine · Mar 19, 2016

Very helpful. Thats a steel 9mm buffer (colt type). They are heavy, but no where near as heavy as the newer buffers from spikes. I say get the tubbs spring if you are on a budget and try the buffer you have. Those buffers are also too short for 9mm and lead to broken bolt catches from too much bolt travel.

You need a spacer to limit bolt travel or just stack some quarters behind the buffer spring. Overall you only want the bolt to clear the bolt catch by about the thickness of 2 quarters.

If you still have problems yoj may need a spikes 9mm ueavy buffer to help tame it down. I would also try non magpul mags to isolate the mags as the cause.

teratos · Mar 19, 2016

Long1MD said:
Scrap it and spend ur money on an H-bar or AR pistol in 556. Never understood the 9mm AR nonsense

I don't get AR pistols.

I've been lucky with my 9mm AR. Spent a lot, though. I have a 9Q heavy buffer and a Tubb Spring. It's been flawless. I don't recall any FTF unless it gets really dirty. It does because of the suppressor. Try the heavy buffer.

tommy gunn · Mar 19, 2016

clandestine said:
Very helpful. Thats a steel 9mm buffer (colt type). They are heavy, but no where near as heavy as the newer buffers from spikes. I say get the tubbs spring if you are on a budget and try the buffer you have. Those buffers are also too short for 9mm and lead to broken bolt catches from too much bolt travel.

You need a spacer to limit bolt travel or just stack some quarters behind the buffer spring. Overall you only want the bolt to clear the bolt catch by about the thickness of 2 quarters.

If you still have problems yoj may need a spikes 9mm ueavy buffer to help tame it down. I would also try non magpul mags to isolate the mags as the cause.

I have a spacer in it. I agree that it seems there is too much travel in the bolt. From what I can see (now mind you I'm no gunsmith) the bolt travels too far back and too fast forward catching the shell before it can clear the reciever. Its not really a buget isssue its just all my cash is spoken for till my next pay. I never really go into these things with a budget I just buy what is needed and then cry when its done and all added up.

Boss94 · Mar 19, 2016

We're you able to get your stuck round out of your barrel?

tommy gunn · Mar 20, 2016

Boss94 said:
We're you able to get your stuck round out of your barrel?

Yes. I pushed it out with a dow rod. I barely pushed on it and it fell right out.

Boss94 · Mar 20, 2016

Just out of curiosity is your bolt a weighted bolt ?

tommy gunn · Mar 20, 2016

Boss94 said:
Just out of curiosity is your bolt a weighted bolt ?

I would guess so. I'm not sure. Its a new frontier 9mm bolt. According to their website it weighs 14.3 ounces.

DutchV · Mar 20, 2016

teratos said:
I don't get AR pistols.

I've been lucky with my 9mm AR. Spent a lot, though. I have a 9Q heavy buffer and a Tubb Spring. It's been flawless. I don't recall any FTF unless it gets really dirty. It does because of the suppressor. Try the heavy buffer.

AR pistols are a thing of beauty. If you haven't shot one, you really should try it. 5.56 has extra muzzle blast but also still has decent velocity.

AR pistols in 9mm make sense because the 9mm cartridge is designed to make most of its velocity in a shorter barrel length. Having a 16" barrel may make it a rifle, but doesn't add much over a shorter barrel.

Look here to see what I mean:

http://ballisticsbytheinch.com/9luger.html

FYI - I'm using a HeavyBuffers 9Q buffer & suggested Wolff XP spring. Had to have my feed ramp (or feed cone) adjusted but it's been pretty good since then.

Have not tried any extra power ammo. Just WWB so far.

erwos · Mar 21, 2016

teratos said:
I don't get AR pistols.

Me neither.

I've been lucky with my 9mm AR. Spent a lot, though. I have a 9Q heavy buffer and a Tubb Spring. It's been flawless. I don't recall any FTF unless it gets really dirty. It does because of the suppressor. Try the heavy buffer.

Ha, you were the one who pointed me towards the Slash's 9Q and that Wolff spring once upon a time. Zero regrets, my 9mm AR has run great. (Note: doesn't have LRBHO, so no idea about that.) The Spike's ST-9X buffer is also a nice choice when combined with a Wolff XP spring, and is cheaper ($50).

In any event, I agree that an upgraded, heavier 9mm buffer would be the way to go.

teratos · Mar 21, 2016

DutchV said:
AR pistols are a thing of beauty. If you haven't shot one, you really should try it. 5.56 has extra muzzle blast but also still has decent velocity.

AR pistols in 9mm make sense because the 9mm cartridge is designed to make most of its velocity in a shorter barrel length. Having a 16" barrel may make it a rifle, but doesn't add much over a shorter barrel.

Look here to see what I mean:

http://ballisticsbytheinch.com/9luger.html

FYI - I'm using a HeavyBuffers 9Q buffer & suggested Wolff XP spring. Had to have my feed ramp (or feed cone) adjusted but it's been pretty good since then.

Have not tried any extra power ammo. Just WWB so far.

I've owned them, and they became SBRs. SBRs make it move, AR pistols make me fall asleep. I have friends I shoot with who love them.

need help with 9mm ar

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