Safety Concern with new AR Build

omegaZ87 · Nov 23, 2013

Hi all,

I just received an AR that a local gunsmith put together for me. I was going over the functionality of the rifle to make myself familiar with it before taking it to the range. One of the things I did was to chamber and eject a round.

Upon inspection of the ejected round, I noticed a small indent on the primer of the round which made me raise an eyebrow. I tried this again with a few more rounds and the same indent appeared on each of them.

This has never happened with any of my other pistols or rifles, which is making me wonder if it is something I should be concerned over. My worry is that this condition may cause a misfire due to contact between the firing pin and printer of the round - or that because the firing pin is already pushing against the round when not fired, the pin may over penetrate the round when fired and cause the round to blow up in the chamber

I do not know much about AR-15s, so could someone let me know if this is normal or if its something I should take the rifle back to the gunsmith to look at. (he's an hour away so I don't wanna make the drive unless I need to)

Thanks

BradMacc82 · Nov 23, 2013

Completely normal. The AR-15 has a "floating" firing pin, basically put, when you close the bolt on a live round the force of the bolt closing allows the firing pin to move slightly forward upon impact, thus leaving a small indent on the primer.

It's ok.

jhcrab · Nov 23, 2013

Have you called the gunsmith; if not call before firing any live loads.

SCARCQB · Nov 23, 2013

BradMacc82 said:
Completely normal. The AR-15 has a "floating" firing pin, basically put, when you close the bolt on a live round the force of the bolt closing allows the firing pin to move slightly forward upon impact, thus leaving a small indent on the primer.

It's ok.

What he said... Completely normal for the AR

Pwilliams1 · Nov 23, 2013

Yep. It's totally normal due to the design of the firing pin/bolt.

If you are so inclined, stripping your gun down and disassembling the bcg will help you get more familiar with the way your gun works. It's a worthwhile and fun adventure.

Deep Creek Rock · Nov 23, 2013

As others have stated - the firing pin in a AR basically free floats - there is no spring. The inertia from the bolt slamming shut causes that pin to push forward and indent the primer.

It should not be an issue, but its a reason why you always point a rifle downrange, or in a safe direction when you release a bolt/slide an action shut. Slamfires are scary things!

CCI does make a harder cup primer for reloading,(milspec) for firearms of these type. I use regular Win small primer, and have not had any issue in MY AR.

The BCG are pretty straight forward to take apart.

omegaZ87 · Nov 23, 2013

So it's safe to take to the range tomorrow? The indent is tiny but I wanted to be sure before putting myself or those around me in danger

Ab_Normal · Nov 23, 2013

omegaZ87 said:
So it's safe to take to the range tomorrow? The indent is tiny but I wanted to be sure before putting myself or those around me in danger

Yes. As long as you keep it pointed in a safe direction when cycling the action no one should get hurt. Also the firing pin can't protrude through the bolt face enough until the bolt is completely in battery to make the round fire.

BradMacc82 · Nov 23, 2013

omegaZ87 said:
So it's safe to take to the range tomorrow? The indent is tiny but I wanted to be sure before putting myself or those around me in danger

It's ok to shoot.

Numidian · Nov 23, 2013

I assume you were letting the bolt fly when chambering the round? If you want to see if it's just the floating pin or not, ride the bolt forward and chamber completely using the forward assist. If it still had a dent after doing it that way, then you'd have some reason to be concerned.

Weber · Nov 23, 2013

It's normal.

Threeband · Nov 23, 2013

Floating firing pins are also found in M1 Garands, M14s, ~~1911 pistols (pre Series 80)~~, SKS rifles, and many, many other firearms.

It is important for you to learn about slam fires:
http://en.wikipedia.org/wiki/Slamfire

Light primer strike in an AR-15 type rifle after dropping the bolt with a loaded magazine inserted

http://en.wikipedia.org/wiki/Slamfire

It is also best that you refrain from chambering live ammunition at home, certainly until you are very familiar with your rifle. Even then, there is rarely a good reason to do so, unless you are actually preparing your defensive weapon for use, for example: http://www.mdshooters.com/showthread.php?t=128596

For familiarization, practice, loading drills, etc. get some snap caps or dummy rounds: https://www.google.com/search?q=sna...7&sourceid=chrome&espv=210&es_sm=122&ie=UTF-8

j8064 · Nov 23, 2013

It's the new NORMAL.

Pinecone · Nov 23, 2013

Actually the CCI #41, military small rifle primer has the same thickness cup as the CCI #450 small rifle magnum primer. And the same priming compound and same amount. The #41 has a couple of thousandths of more space between the cup and anvil.

For safety, CCI #41, CCI #450, Remington 7 1/2 are the recommended primers for AR use.

Many people has used other primers, but they may be running at the edge.

Goose Guy · Nov 23, 2013

If it means anything, mine (never fired) does it too.

dauntedfuture · Nov 23, 2013

Normal. Stay awar from rem 6.5 primers if your new to the ar and a reloader.

jrumann59 · Nov 26, 2013

This is most common when you slingshot the charging handle, pull it all the way back and let it go, to close the bolt. It is less prominent when you release the bolt via the bolt release button. Who would of thunk 3/4" less travel would make that much difference.

John from MD · Nov 29, 2013

Threeband said:
Floating firing pins are also found in M1 Garands, M14s, 1911 pistols (pre Series 80), SKS rifles, and many, many other firearms.

I have never seen a 1911 pistol with no firing pin spring. Even the family hand me down from 1924 has a firing pin spring. Perhaps you are talking about a clone of some type?

Threeband · Nov 29, 2013

You're right. 1911s do have a firing pin spring. I was confusing the "inertia" type firing pin (pre-Series 80) with a floating pin. There has been some controversy about the safety of the pre-Series 80 inertial pin, which led me to confound the two types.

Garands, M1 Carbines, and M14s/M1As, M16s/AR15s do have floating pins though.

Magnumite · Nov 30, 2013

"This is most common when you slingshot the charging handle, pull it all the way back and let it go, to close the bolt."

This occurs every time the gun fires and chambers the next round as well. Same as pulling the bolt back all the way when first charging the rifle.

Safety Concern with new AR Build

The #1 community for Gun Owners of the Northeast

Member Benefits:

Member

Ultimate Member

Active Member

Get Opp my rawn, Plick!

Active Member

.._. .._ _._. _._ .._

Member

Ab_member

Ultimate Member

Banned

USMC

The M1 Does My Talking

Garrett Co Hooligan #1

Ultimate Member

Skooma lord

Member

DILLIGAF

American Patriot

The M1 Does My Talking

Ultimate Member

Users who are viewing this thread

Log in

Forum statistics