Palmetto AR pistol help

[Nwilliams184]

What could be causing my AR pistol to fire multiple rounds with one trigger pull? Purchased complete pistol from PSA. Brand new out the box today. 8.5 inch barrel, .300 blackout

[Nanuk]

Sear not engaging, trigger pin walked out? I would contact them.

[rickyrick]

Do you know how to perform a military style function check on an unloaded rifle? That could tell us a lot.
Being that it’s brand new, I’d just get ahold of the manufacturer and let them figure it out.

[Nwilliams184]

I'm not familiar with performing a military style function check. I can take it down, clean and put back together just fine.

The first few rounds fired perfectly then had a jam. Range officer came over checked and discovered the previous round's primer was stuck and caused the jam. Fixed and fired away. After a few more rounds that's when I noticed multiple rounds being fired. I thought at first I was anticipating the recoil and pulled the trigger again slightly or something. It happened a few more times and this range has strict "1 round per second." It was pretty crowed and started drawing attention. I tried again after the range cleared out, loaded two rounds into magazine and with one trigger pull both rounds were fired.

I tried emailing Palmetto through their site but keep getting an error message. I'm assuming they will be closed on Monday so I'll try them Tuesday. Sucks, I was really excited when this came today. I'm just hoping its something simple and not a long turn around time

Thanks for your help and any other suggestions anyone has.

[Uncle Malice]

Do not touch the rifle and contact PSA immediately. You're sitting on a potential felony if you knowingly shoot the gun.

They'll get you taken care of right away because this is a BIG deal.

[Bartholomew Roberts]

You need to perform a function check using an unloaded rifle pointed at a safe backstop. The results of that should identify the problem.

[stagpanther]

VERY unusual to get a multiple discharge on a single trigger pull in a conventional mil-spec type fire control group set-up--are you keeping the pistol still, meaning you are not allowing the recoil to move the gun back towards you, during firing? Test your trigger group and make sure the entire cycle (pull, sear and disconnector engagements) and trigger reset are all functioning as they should. After that, check the safety enagament and ensure it works properly in all settings

Here's a simple trigger group check:

remove the upper from the lower, and put the safety on fire. while holding the receiver with both hands, pull the trigger all the way back as far as it can go, and then pull the hammer back so that it engages the disconnector and is held in place. Be sure at all times while doing this function check to keep a finger between the hammer and the bolt catch--you should avoid having the hammer strike the bolt catch. Release the trigger--and the disconnector should let the hammer go with an obvious "click" BUT the hammer should be reset to engage the trigger--in other words the hammer should not fall and hit the bolt catch (or your finger held in front of it). The trigger should now be in the proper reset position--simply pull on it and it should release the hammer (again, keep a finger in front of the hammer so it does not strike the bolt catch). If there is anything wrong with this check--or the safety checks--box her up and return to PSA immediately.

You could also have a problem with headspacing and proper bolt functioning--it's not impossible that your firing pin may be out of compliance--especially with evidence of blown/pierced primers. If your trigger group is functionally in compliance--my guess is that your issue(s) lie here. Also try different quality ammo.

Don't freak out--my guess is that the solution is probably fairly simple.

You sound like you are fairly new to these types of weapons--upon receiving the gun did you FIRST read the owner's manual cover to cover? Did you do a complete strip and clean before use?

[Mobuck]

"Do you know how to perform a military style function check on an unloaded rifle? That could tell us a lot."

This procedure(or something similar) should be followed with any/every new semi-auto firearm before filling the mag and blasting away.

[Nwilliams184]

Thanks everyone for your input and suggestions. To answer a few questions, I am new the AR platform with this being my 2nd AR but first pistol. I did read the manual and I always perform to "my knowledge" a basic check to make sure everything seems to be working correctly.

After reading Stagpanthers post, I performed the following and everything seemed fine.

remove the upper from the lower, and put the safety on fire. while holding the receiver with both hands, pull the trigger all the way back as far as it can go, and then pull the hammer back so that it engages the disconnector and is held in place. Be sure at all times while doing this function check to keep a finger between the hammer and the bolt catch--you should avoid having the hammer strike the bolt catch. Release the trigger--and the disconnector should let the hammer go with an obvious "click" BUT the hammer should be reset to engage the trigger--in other words the hammer should not fall and hit the bolt catch (or your finger held in front of it). The trigger should now be in the proper reset position--simply pull on it and it should release the hammer (again, keep a finger in front of the hammer so it does not strike the bolt catch). If there is anything wrong with this check--or the safety checks--box her up and return to PSA immediately.

I've since, cleaned and lubricated, which I did not do before. Someone mentioned it could be an ammo problem. That day I fired Sig Sauer Elite 125gr and Fiocchi 125g. There wasn't too wide of a selection.

Do you think I should head back out to range or wait until I hear back from PSA?

Thanks again everyone.

[stagpanther]

You might not get a yea or nay answer straight up for liability reasons--it's nearly impossible for anyone (myself included) to make that call based on virtual internet doctoring.

[marine6680]

Doubling due to slam firing is possible in an AR but it's not a common thing... But it could be prudent to try different ammo.


A function check is always a good idea.

With an unloaded firearm... Pointing in a safe direction.

Operate the charging handle to ensure the hammer is cocked and ready.

Engage the safety and attempt to pull the trigger. The hammer should not fall.

Disengage the safety.

Pull the trigger and hold it to the rear. The hammer should fall.

Operate the charging handle, while ensuring that you keep the trigger pulled to the rear.

Slowly allow the trigger to move forward into the at rest position. You should hear and feel the hammer reset, by coming off of the disconnector and coming to rest on the trigger sear.

Pull the trigger again. The hammer should fall.


You can do this check with the upper receiver off of the lower, but as was mentioned, care should be taken to prevent the hammer from falling with full force against the bolt stop, as it can damage things.

Doing the check with the upper off, can allow you to see what is happening.

After every cleaning and reassembly, you should perform a function check... This applies to all firearms. The process is different, based on the type of firearm, but the steps are all fairly similar.


If the rifle passes the function check... That does not rule out a potential problem with the fire control group, but it makes it less likely.


Bring this is a pistol, and the Dynamics of shooting an AR pistol... You may be doubling unintentionally.


One problem many have is failure to use proper follow through techniques.

You want to pull the trigger, and ensure you keep the trigger pulled rearward the entire time during the shot. You do not release your finger until the firearm has settled from the recoil, and your sights are on target again, ready for the next shot.


The safest course of action is to call PSA... Let them look it over. Keeps you out of the legal hot seat. Talking to the guys running the range, they may be willing to function check the rifle for you with live ammo... A licensed gunsmith may as well. A gunsmith may charge you though.

[MagnumWill]

Originally Posted by Uncle Malice

Do not touch the rifle and contact PSA immediately. You're sitting on a potential felony if you knowingly shoot the gun.

They'll get you taken care of right away because this is a BIG deal.

Ugh...not this again... smh

[HiBC]

You said something about jamming due to a primer floating around. Primers falling out is really not OK. Why did it fall out?

Bits of primer in the fire control parts could be a problem.

Bits of primer inside the bolt could be a problem.

A little wear on the hammer hooks,or "trigger tuning" could be a problem.
But on a new gun???

The AR pistol has less mass than the AR rifle.Its possible to have a lighter trigger that technically may be be functional,but if your hold on the gun allows some float,a rhythm can develop with the bolt carrier slamming shut that is a lot like the bump fire effect.

In any case,its not safe,it attracts unwanted attention to you,and you really can get in trouble with a malfunctioning gun that goes full auto if you don't take it out of service and fix it. Felony trouble.
Arguably the safest solution is send it to PSA and let them fix it.Its new,its not right.That should cost you nothing. AND, if you get the return authorization,etc,you should be able to FedEx direct to PSA and they can return direct to you(Over 21 signature)

You COULD for not much money you can get DPMS or Rock River or Brownell's replacement mil-spec trigger parts. Just replace the parts with a new kit and it SHOULD work.You can get a whole lower parts kit for $50 or so.
If you want a little nicer trigger, get the Rock River 2 stage national match.Probably $120

But if you do anything yourself,its not so much PSA's problem anymore.

[Omaha-BeenGlockin]

Sounds like the hammer spring might be on backwards

[GLK]

Originally Posted by MagnumWill

Ugh...not this again... smh

I was wondering if I were the only one.

[Kreyzhorse]

Sounds like the hammer spring might be on backwards

I wondered the same thing.

I'd also have someone fire as well to rule out that the OP isn't unintentionally doing it.

[Theohazard]

In my experience, most of the time someone has multiple rounds fire with an AR-15 it’s simply due to inadvertent bump-firing.

[stagpanther]

I was wondering if I were the only one.

Flogging a dead horse is as good a way as any for meeting that new year's resolution of losing weight.

[Nwilliams184]

You said something about jamming due to a primer floating around. Primers falling out is really not OK. Why did it fall out?

Bits of primer in the fire control parts could be a problem.

Bits of primer inside the bolt could be a problem.

While I was performing the trigger group check, I did notice a lot of small grit/debris down there.

[stagpanther]

The 300 BO is generally a soft shooting round--I have a pistol in 300BO and have pushed supersonic loads as far as I can and it still is a soft shooting rig--though it does make a heck of a lot of noise unsuppressed. Bunch of junk inside a gun--any gun--NIB is not unusual either.

Spent cases usually tell the story--or give strong hints--as to what might be wrong with a gun. If you're not already familiar with them--look up, or better yet buy a reloaders manual--the signs of over-pressure in a case and what might cause them.

[Roughedge]

I had the same problem on my PSA 9mm.

[stagpanther]

firing pin spring??

[Theohazard]

Originally Posted by Roughedge

I had the same problem . Changed out the firing pin spring with a little heaver one and solved the problem.

ARs don’t have firing pin springs.

[SDF880]

500+ rounds thru my PSA 300BLK pistol and no issues!

Did you take the bolt apart, inspect/clean and reassemble?

[FrankenMauser]

ARs don’t have firing pin springs.

Many 9mm ARs do ... which is precisely what stagpanther was responding to.
And there are BCGs available that have firing pin springs for 'rifle cartridge' use (to render the firing pin not free-floating).