AR15.Com Archives
 does a non-shrouded carrier bread firing pins?
rightwingnut  [Member]
10/3/2011 6:11:55 PM
I was thinking of trading all my "full-auto" carriers for "semi-auto" carriers w/ non shrouded firing pins so that if I have a dis-connector break...I don't end up like that guardsman who let some dip shit take his old OLY to the range... I recall TonyK saying he did this for all his title 1 ARs and it makes a little sense to me.

I know you loose a little weight when you go to that type of carrier, but are there any other mechanical issues w/ a non-shrouded carrier? Like when the BCG open up, are you cocking the hammer much w/ the firing pin before the carrier hits the hammer face? Has anyone ever had a firing pin broken in the back from a non-shrouded carrier?
Cole2534  [Team Member]
10/3/2011 8:40:10 PM
Olofson didn't fuck up when he had a malfunctioning gun, Olofson fucked up big when he knowingly gave it to another individual.

In short, I'm not worried.

Edit: that's what I'm remembering off hand about the charges on which he was convicted.

Posted Via AR15.Com Mobile
AlexanderA  [Member]
10/3/2011 8:49:17 PM
The "non-shrouded" (beveled) bolt carrier, along with the notched hammer and the small-diameter firing pin, is a solution Colt came up with circa 1971 –– after prodding from the ATF –– for the problem, not so much of a broken disconnector, but a removed disconnector. (Some people thought they were being clever by simply removing the disconnector to achieve automatic fire. In reality this was a highly dangerous and unreliable practice, resulting in hammer follow-down, light primer strikes, and possible firing out of battery.) The civilian AR-15 was actually taken off the market for a time, until this modification was implemented. During that time, there was an opening for the Armalite AR-180, which was temporarily the only "black rifle" available –– but that's another story.

If you use a non-shrouded bolt carrier and a notched hammer with a standard (large diameter) firing pin, the gun will jam every time. Either the hammer has to be non-notched, or the firing pin has to be small diameter. But why worry about whether everything matches? For reliability, plus legality, I would use a shrouded semi bolt carrier (with the long cutout) and a non-notched semi hammer (without the hook for the auto sear). That way you can use any firing pin. I personally think the odds of a broken disconnector are rather slim.
tony_k  [Moderator]
10/3/2011 9:41:39 PM
Originally Posted By rightwingnut:
I was thinking of trading all my "full-auto" carriers for "semi-auto" carriers w/ non shrouded firing pins so that if I have a dis-connector break...I don't end up like that guardsman who let some dip shit take his old OLY to the range... I recall TonyK saying he did this for all his title 1 ARs and it makes a little sense to me.

FWIW ... you (and the other posters) are correct in that non-shrouded carriers are the last line of defense against runaways if the lower fire-control system breaks.

But I don't use semi carriers –– with the exception of my 9mm LRM M169 upper, all my uppers are factory Colts, and have the factory Colt full-auto carriers they came with. Most are sub-16" and used on my SBRs, but the non-SBRed ARs also are Colts with 16+" uppers and Colt factory carriers.

While I'm as paranoid and careful as I can be, I look at disconnector malfunctions this way: If it breaks and you experience a runaway, you stop shooting, make the gun safe, and put it away until it is repaired. IMHO, it would be very difficult for LE or ATF to get a conviction if you immediately recognize the malfunction and address it.

OTOH, if your AR suddenly starts shooting bursts and mag dumps, and you proceed to keep shooting it like that for the rest of the range session or until your ammo runs out ... and bring it back next week and do the same thing, well then, IMHO you are in jeopardy of prosecution.

BTW, what I did post earlier is that all my FAs have .154 fire-control groups and all the semis have .170 fire-control groups (they either came that way, or I drilled them out). That way, it is impossible for my FCG spares to wind up in the wrong ARs.

Your Mileage May Vary.
rightwingnut  [Member]
10/4/2011 3:57:27 AM
Originally Posted By AlexanderA:
If you use a non-shrouded bolt carrier and a notched hammer with a standard (large diameter) firing pin, the gun will jam every time. Either the hammer has to be non-notched, or the firing pin has to be small diameter. But why worry about whether everything matches? For reliability, plus legality, I would use a shrouded semi bolt carrier (with the long cutout) and a non-notched semi hammer (without the hook for the auto sear). That way you can use any firing pin. I personally think the odds of a broken disconnector are rather slim.


So, if I use a hammer w/ the notch on the face, and a standard diameter FP in a non-shrouded carrier, the hammer will snag the FP "every time" the BCG tries to go forward even if the disconnector is present and functioning properly? Or, are you saying that this will only happen if the disconnector breaks/is removed?

Looking a lower here, it has a notched hammer face, a shrouded Bravo carrier w/ .466" enclosed section at the bottom of the back. What parts would I need so it would jam if the disconnector hook broke off?
rightwingnut  [Member]
10/4/2011 4:05:05 AM
Thanks Tony for chiming in and for clearing up my recollection of what you said sometime in the past. I understand that it would be pretty hard for them to get a convition, but if it isn't too much trouble, I would like to prevent any possibility of ever being put in a position of possibly being indited. Sometimes the agents are even at the range and they are I can't trust that they would have the intellectual capability to distinguish an innocent malfunction even if they had good will towards the shooting public.
Circuits  [Team Member]
10/4/2011 4:54:01 AM
Originally Posted By rightwingnut:
So, if I use a hammer w/ the notch on the face, and a standard diameter FP in a non-shrouded carrier, the hammer will snag the FP "every time" the BCG tries to go forward even if the disconnector is present and functioning properly? Or, are you saying that this will only happen if the disconnector breaks/is removed?


With a standard diameter FP and non-shrouded carrier, it *can* happen, but won't necessarily happen every time, even if the disco is present and functioning properly.

If the disconnector is not present or is not functioning properly, any non-shrouded carrier and notched hammer will snag the FP every time.
rightwingnut  [Member]
10/5/2011 4:52:57 AM
Originally Posted By Circuits:
Originally Posted By rightwingnut:
So, if I use a hammer w/ the notch on the face, and a standard diameter FP in a non-shrouded carrier, the hammer will snag the FP "every time" the BCG tries to go forward even if the disconnector is present and functioning properly? Or, are you saying that this will only happen if the disconnector breaks/is removed?


With a standard diameter FP and non-shrouded carrier, it *can* happen, but won't necessarily happen every time, even if the disco is present and functioning properly.

If the disconnector is not present or is not functioning properly, any non-shrouded carrier and notched hammer will snag the FP every time.


So, if one wants to go this route, he has to use the non shrouded Carrier and some small OD FP. Are these special FP expensive and/or hard to come by?
AlexanderA  [Member]
10/5/2011 8:22:16 AM
Are these special FP expensive and/or hard to come by?


Not any more expensive or hard to come by than standard firing pins. You just have to know what you're looking for.
AN94NK  [Team Member]
10/5/2011 7:24:39 PM
Originally Posted By tony_k:
Originally Posted By rightwingnut:
I was thinking of trading all my "full-auto" carriers for "semi-auto" carriers w/ non shrouded firing pins so that if I have a dis-connector break...I don't end up like that guardsman who let some dip shit take his old OLY to the range... I recall TonyK saying he did this for all his title 1 ARs and it makes a little sense to me.

FWIW ... you (and the other posters) are correct in that non-shrouded carriers are the last line of defense against runaways if the lower fire-control system breaks.

But I don't use semi carriers –– with the exception of my 9mm LRM M169 upper, all my uppers are factory Colts, and have the factory Colt full-auto carriers they came with. Most are sub-16" and used on my SBRs, but the non-SBRed ARs also are Colts with 16+" uppers and Colt factory carriers.

While I'm as paranoid and careful as I can be, I look at disconnector malfunctions this way: If it breaks and you experience a runaway, you stop shooting, make the gun safe, and put it away until it is repaired. IMHO, it would be very difficult for LE or ATF to get a conviction if you immediately recognize the malfunction and address it.

OTOH, if your AR suddenly starts shooting bursts and mag dumps, and you proceed to keep shooting it like that for the rest of the range session or until your ammo runs out ... and bring it back next week and do the same thing, well then, IMHO you are in jeopardy of prosecution.

BTW, what I did post earlier is that all my FAs have .154 fire-control groups and all the semis have .170 fire-control groups (they either came that way, or I drilled them out). That way, it is impossible for my FCG spares to wind up in the wrong ARs.


Your Mileage May Vary.


That actually a great idea when you have RR's & semi's sitting around in the same safe. That way the ATF CAN NOT say your spare M16 FCG's can be used in an unregistered lower.
j3_  [Team Member]
10/7/2011 10:43:51 AM
Originally Posted By rightwingnut:
Originally Posted By Circuits:
Originally Posted By rightwingnut:
So, if I use a hammer w/ the notch on the face, and a standard diameter FP in a non-shrouded carrier, the hammer will snag the FP "every time" the BCG tries to go forward even if the disconnector is present and functioning properly? Or, are you saying that this will only happen if the disconnector breaks/is removed?


With a standard diameter FP and non-shrouded carrier, it *can* happen, but won't necessarily happen every time, even if the disco is present and functioning properly.

If the disconnector is not present or is not functioning properly, any non-shrouded carrier and notched hammer will snag the FP every time.


So, if one wants to go this route, he has to use the non shrouded Carrier and some small OD FP. Are these special FP expensive and/or hard to come by?


Colt and Bushmaster were the only places I ever got an ar15 firing pin with the correct size collar. Dpms sells them but they are a little over sized.
I only use SP1 parts by choice. Never had any problems from using them but it is difficult to find carriers now with unshrouded firing pins. Notched hammers seem to be going away also.

rightwingnut  [Member]
10/9/2011 4:02:08 AM
Im not sure whether I have notched hammers or not. Any pics of either type. Maybe I can get fp from saw armament.
Circuits  [Team Member]
10/9/2011 5:17:27 AM
http://biggerhammer.net/ar15/hammers/

Top right and bottom row are notched hammers.
rightwingnut  [Member]
10/9/2011 9:58:44 PM
Originally Posted By Circuits:
http://biggerhammer.net/ar15/hammers/

Top right and bottom row are notched hammers.


Thanks so much easier I believe every hammer I have ever had is notched like that. At least the hammers wont be hard to find.

Anyone know where to get new non-shrouded carriers?