Forward assist notches on AR 10 bolt carrier

[leftiye]

Hi, I recently purchased an upper and bolt carrier group for an AR 10. The sweetheart sent me an upper with a forward assist (which I had selected specifically), but there are no forward assist notches on the bolt carrier. Seems ridculous, but there are apparently a lot of guns out there set up this way as finding a bolt carrier with the notches is fairly difficult. I would prefer the forward assist to be included and for it to have a reason for being there. Can anyone help me with the location of these notches - how far forward from the rear of the bolt carrier, and how they are spaced. Once I have this I will be able to look at cutting some in the bolt carrier. Thanks, Ted

[Artful]

Hmm, I don't have an Ar-10 but there seems to be more than one standard for the parts
http://www.biggerhammer.net/stoner/sr25var10/ar10vsr25.html


CARRIER: The AR-10B carrier is virtually identical to that of the SR-25. It is externally phosphated instead of chrome plated as with the SR-25, but is chrome plated in the gas expansion chamber like the carrier of the M-16. The carrier key surface is .010 inch farther from the boreline than that of the KMC carrier, and .030 further to the rear for better gas transfer into the carrier. Like the KMC carrier, the ArmaLite carrier will not allow a standard width hammer to enter the ArmaLite Carrier Assembly. Initial testing has shown that the carrier and bolt group is interchangeable with the KMC components.

http://762ar.com/wp-content/uploads/2011/09/Young-308-BCG1.jpg

https://delta3tactical.com/store/product_images/n/400/armalite-ar10-bolt-and-carrier-assy__31563_zoom.jpg

DPMS bolt carrier
http://www.brownells.com/userdocs/schematics/dpms-boltcarrierassy.gif
http://www.brownells.com/schematics/DPMS-Panther-Arms-/Bolt-Carrier-Assembly-sid811.aspx

http://308ar.com/carriers.htm

[Dan Cash]

Forward assist will only assist you in getting a bad round really stuck. If bolt does not go into battery from driving spring, eject it and try another. Stuck cartridge in an AR is sure hard to remove.

[leftiye]

Thaks for your help. I was getting to think no one would answer. So I might as well send him back the upper receiver, and get a slickside?

[Petrol & Powder]

IMHO the forward assist is a solution in search of a problem. I can understand how it may be desirable to force a dirty cartridge into a dirty chamber when you don't have time to clean the rifle, like say in combat. However, most of the time the forward assist is never used. It adds weight, complexity and bulk. I agree with Dan Cash, the forward assist is more likely to assist you with sticking a bad round in the chamber than to assist getting the bolt closed on a good round.
I've never been a huge fan of the direct gas impingement system of the AR. I believe a lot of the improvements to the platform, like the addition of a forward assist, have been methods to deal with the venting of combustion gases inside the receiver.

[downzero]

I've never been a huge fan of the direct gas impingement system of the AR. I believe a lot of the improvements to the platform, like the addition of a forward assist, have been methods to deal with the venting of combustion gases inside the receiver.

Direct gas impingement is the primary innovation that the AR design brought to the table. It reduced unnecessary complexity and eliminated a ton of moving parts and weight.

The forward assist was added because those who had dealt with the previous generations of rifles couldn't handle the fact that the op rod no longer worked in both directions. As noted by this thread, it is a virtually useless feature that perhaps has some use in combat but even that is questionable. The original M16 design did not have it and it is not a byproduct of direct impingement.

[Petrol & Powder]

Not to drift this thread wildly away from the OP, but the assertion that, "The forward assist was added because those who had dealt with the previous generations of rifles couldn't handle the fact that the op rod no longer worked in both directions"; is a bit of a stretch. I assume the forward assist is there to allow the user to assist in moving the carrier/bolt forward when it doesn't go forward on it's own :-?. As to why the forward assist was added,.......
I can only assume the bolt was failing to close and the non-reciprocating operating handle was of no value when faced with that problem.

Direct gas impingement was an innovation and it does reduce moving parts and weight but at the cost of introducing hot/dirty gases into the receiver. That's a useful innovation if your only goal is to reduce weight and moving parts. It's not an innovation I embrace.

[leftiye]

I myself think the lack of a bolt handle is sheer assininity - ego - on the part of Stoner. More parts or not, a piston system is still superior. Plus, if you delete the on top operating slide, there won't be more parts with a piston. I'm not a fan of people who push "cool" "improvements" at the expense of function. There are more than a few names on the Viet Nam wall that were trying to un jam an M16 at the wrong moment. Yeah, there are still people around who still remember. The fact that 40 years of solutions and corrections have made it one of the world's most prevalent battle rifles isn't exactly a vindication.

Though slim, the chance that I may need a round in the chamber rather than a jammed gun sometime (especially if I don't have a bolt handle) makes me want the forward assist to work.

[Geezer in NH]

The problem in the design was the use of powder not designed for the gun and the no cleaning needed with no cleaning tools issued with it.

Old news at best

[leftiye]

It's not even news (no news at all) but it was what we were talking about. Doesn't have to be news.

[JSnover]

I'm not a fan of that gas system. Never trusted it and I cleaned my M16 so often, I refuse to own one, but that's just me.
As a machinist I was kind of hoping someone would answer the question. Maybe try the military rifle section. Somebody has to have a bolt carrier and a way to measure it.

[Mumblypeg]

I have never found a need for the forward assist. I take care in loading my ammo and have never had a F T feed. And yes I have fired many rounds in 4 different AR's. My first one was an SP model without FA. I still think they are great guns no matter what others may say. Any problems that I may have had were always magazine related. Just my thoughts.....

[leftiye]

I've been looking at (for) carriers with the forward assist notches on them. Most of those I found did not have notches. But I did find a couple that did. On at least one of these the notches went most of the length of the carrier.

You can easily locate the rearmost that you could possibly need a notch by putting layout blue or prussian blue on the forward assist finger and engaging it to touch the bolt when the bolt is in fully closed position. Then you need to determine how far open the carrier could be (maximum) in a jam situation where you might want to try to use the forward assist. Notches could be cut with an abrasive cutoff wheel in a toolpost grinder (with an angled cutting edge) on a lathe with the bolt carrier in the chuck, and use the compound feed to measure intervals.

[JSnover]

It could be as simple as that. You could determine the proper angle based on the nose geometry of the forward assist. I doubt the spacing is critical as long as you're close.

[randyrat]

I believe it was more for noise in a combat situation than a dirty weapon. Normally you let the bolt slam forward, but if you are in a bad situation in a night fight and you don't want the enemy to know your position, you can reload with less noise...No slamming

If you need the forward assist because of a dirty weapon, your in deep DO DO

MORE is too strong of a word.........Dirty chamber your in DO DO... dirty path for your bolt is still bad but in a better situation with a forward assist

[JSnover]

To reload quietly with a functional rifle after inserting a fresh magazine you would hold the charging handle to the rear, release the bolt catch and use charging handle to control the forward movement of the BCG. Then you should strike the forward assist to make sure you are in battery.
I suppose that could be necessary, but if your rifle is empty the enemy already knows you're there.

[randyrat]

Changing fire positions, in close quarter fire fight, just after you lay down suppressive fire for your buddy to move. They don't know you moved unless you slam that bolt forward.

[garym1a2]

If you really want an AR15 to lock up push the forward assist button on a round that did not go fully into battery. If you are lucky you will next learn the tecnique of banging the buttstock on the ground while pulling back on the charging handle.