Have a AR function question

[oldgrayone]

Today at the range a fellow on the other end had a brand new DPMS go to shit on him today. It was his first AR15 and he was shooting white box 223 55grn stuff. He loaded 1 round in his mag cycled the bolt and fired. His mag blew out of the rifle with the mag spring and bottom cap flying across the bench. I looked at the fired case and it had about 50% of the rim gone and the primer was blown out.

I beleive the cause was due to him easing the bold closed on the round and the bolt did not go full closed. When I looked at it, if the bolt was not allowed to slam home it would stay open about 3/8 of an inch.

My question is with the bolt 3/8" from full closed will/should the weapon fire if functioning correctly?

With the bolt 3/8' from full closed you could pull the trigger and this would move the bolt forward and then go click. I told him to pack it up and take it back to the shop he just picked it from and see if they could sort it out.

 

[jakhamr81]

Re: Have a AR function question

The gun should not, I say again SHOULD not fire unless it is in full battery. That said, I have scene a gun fire and blow the magazine apart. It was determined that the cause was because the weapon was not in full battery when it was fired. We were using a training "blue tip" round at the time that used a blow back operating bolt.

 

[dbsinh2o]

Re: Have a AR function question

By design, this should not be able to happen with an AR (firing with the bolt out of battery).

Until the bolt rotates all the way into the locked position, the firing pin cannot strike the primer.

 

[jawa]

Re: Have a AR function question

Wonder if he was shooting 5.56 in a .223 chamber...

 

[Tbag]

Re: Have a AR function question

And this is why you don't hang on to the mag while firing as your fingers will get mangled.

 

[dbsinh2o]

Re: Have a AR function question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jawa</div><div class="ubbcode-body">Wonder if he was shooting 5.56 in a .223 chamber... </div></div>

I'd sure suspect the ammo before the rifle.

My Bushmaster Predator was advertised as having a "hybrid" chamber (they claimed it could use .223 or 5.56). The first time I fired Federal 5.56 in it, about 1 out of 6 primers blew out, and the headstamps were getting smeared from the overpressure. I called Bushmaster and the response I got was "Oh yeah, those chambers are a little tight to fire 5.56 in. Send it back and we'll reem out the chamber to 5.56."

Keep in mind that the hybrid chamber was somewhere between the two, so a .223 chamber would cause an even higher overpressure.

I think the part with the bolt not closing all the way if you ride the charging handle is probably due to the tight tolerances of a new gun.

Think you made the right call on the 5.56 being the cause.

 

[Ballista One]

Re: Have a AR function question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dbsinh20</div><div class="ubbcode-body">By design, this should not be able to happen with an AR (firing with the bolt out of battery).

Until the bolt rotates all the way into the locked position, the firing pin cannot strike the primer.</div></div>

Smart man... Most likely an ammo issue.

 

[Casey Simpson]

Re: Have a AR function question

Its also why clowns ought not be able to buy guns at Walmart and run out to the nearest range and hurt themselves and others, but oh well, so what.

Guns aren't foolproof.