Can you hold the forward assist when shooting an AR-15?

[Carl N. Brown]

Back to the opening post:

The bolt forward assist plunger is designed to close a dirty or fouled bolt.
It is not designed to hold the bolt closed against pressure from gas impingement or piston action.
Never was its design intent.
I would not put my thumb on an AR Forward Assist Plunger, except to assure that the bolt was fully closed before firing.

But I think I have found a possible reason an AR that I shot to check out a new trigger mechanism was missing its Forward Assist Pawl.
That flimsy lil thang is not robust enough to hold a bolt closed.

 

[lysanderxiii]

A buddy of mine is trying to make his suppressed .300 Blackout as quiet as possible. He's been allowed to shoot pigs on a tiny piece of land that borders some supposedly rather unpleasant neighbors.

He asked me if there would be any issue holding the forward assist while shooting to keep the action from cycling. I'm not sure if he'll hurt his thumb or action by doing it so I said I'd ask around.

CAN you? You can try, but it will do one, or more of the following things:

1) Damage the FA pawl
2) Damage the serrations in the bolt carrier, and
3) Damage his thumb, or whatever is holding the FA down.

 

[Slamfire]

Sure sounds like a "hold my beer" moment.

 

[herrwalther]

Sure you can hold down the forward assist while shooting. Doesn't mean you should. Damage to your thumb. Damage the rifle. Take your pick why it is a bad idea.

If he wants to go quieter, he should get a bolt gun and learn how to quietly operate that. Or a single shot. Guess they make those in 300Blk now too.

 

[Skylerbone]

You can try, but it will do one, or more of the following things:

1) Damage the FA pawl
2) Damage the serrations in the bolt carrier, and
3) Damage his thumb, or whatever is holding the FA down.

1. the pawl is made from heat treated tool steel, not likely to be deformed or otherwise damaged.
2. the bolt carrier is heat treated 8620 and typically runs a minimum 68Rc, again damage is unlikely.
3. while it may sting, you are only absorbing the amount of energy that would otherwise be absorbed by the buffer and its spring and the FA being captured, can only move your thumb back a fraction of an inch. Damage not likely.

I don’t advocate any of the above, certainly better choices to be made vs. misusing the FA to quiet the rifle, but I cannot foresee damage of a permanent sort from a single or even occasional event.

The other question I’d have is how you would stabilize the shot with your thumb stretched out so awkwardly. Foolish but I don’t believe dangerous.

Some actions such as the Savage below (Model 7) are designed to allow the bolt knob to lock the action, rendering this semi-auto a single-shot. These were manufactured using far softer steels than either AR component being discussed. Granted, .22lr does not pack the energy of 5.56 but again, consider the recoil energy of that AR and a few shots would be trivial IMO.

 

[someguy2800]

If something were to get damaged it would likely be the little roll pin. From having held the bolt shut with my palm against a side charging handle on a 7.62x39 upper with no ill effects, I think we a getting a little carried away with talk of serious damage or injury. I would say the most likely result would be a sprained thumb, but the bolt assist does not have that much travel.

 

[lysanderxiii]

1. the pawl is made from heat treated tool steel, not likely to be deformed or otherwise damaged.
2. the bolt carrier is heat treated 8620 and typically runs a minimum 68Rc, again damage is unlikely.
3. while it may sting, you are only absorbing the amount of energy that would otherwise be absorbed by the buffer and its spring and the FA being captured, can only move your thumb back a fraction of an inch. Damage not likely.

1. The pawl is made from AISI 1144 and treated to RHc 44 to 48, not supper hard.
2. The bolt carrier is treated to 15N-89.5 to 91.0, which is the equivalent to RHc 58 to 62. If it were 68, the chances of chipping would be greater. I have seen chipped serrations due to FAs being stuck forward.
3. The pressure inside the carrier cavity is around 2000 psi with an effective piston area of 0.19 square inched, so the pulsed load is just under 400 pounds. You put your thumb behind that and report back, if you think some form of damage is unlikely.

 

[mcb]

1. The pawl is made from AISI 1144 and treated to RHc 44 to 48, not supper hard.
2. The bolt carrier is treated to 15N-89.5 to 91.0, which is the equivalent to RHc 58 to 62. If it were 68, the chances of chipping would be greater. I have seen chipped serrations due to FAs being stuck forward.
3. The pressure inside the carrier cavity is around 2000 psi with an effective piston area of 0.19 square inched, so the pulsed load is just under 400 pounds. You put your thumb behind that and report back, if you think some form of damage is unlikely.

View attachment 1081652

Mil spec bolt carries are most often cast from 8620 (this is a low carbon steel, ~.20% carbon). Steel with this low of carbon content cannot be hardened much past HRC45 with quench and temper or austemper heat treatments let alone nearly 60. Bolt carrier castings are machined to near final shape. They are then case hardened (surface carburized, heated in a high temperature and high carbon atmosphere and carbon is absorbed into the steel transforming the surface layer from austenite to martensite). This case hardening results in a surface that is typically HRC 58-62 but it only penetrates the surface of the part 0.010 -0.015 in the case of a bolt carrier (the process can be adjusted for less or more penetration). The core of the part remains relatively soft. The bore in the carrier that the gas rings slide on is then then ground to final dimension/finish. This soft core and hard out surface gives the part good wear resistance while not making the part a grenade in the event of a bolt carrier rupture. The soft core helps ensure you don't create many high velocity fragments in a failure (the same reason gun barrels are relatively soft and made from medium carbon steels and comparable stainless steels.).

If the forward assist is not mechanically stuck but simply held forward then remember as the bolt start to cycle backwards it will push the forward assist rearward and given the angled approach the forward assist makes to the side of the bolt carried it will eventually move to the side far enough to disengage the bolt carrier. Try it, hold the forward assist forward with a thumb and pull the charging handle, the forward assist with chatter under your thumb as it slips off each notch in the bolt carrier.

And the proper answer is no forward assist at all. Eugen Stoner was against it. Get a gas system with an off selection...

 

[mavracer]

3. The pressure inside the carrier cavity is around 2000 psi with an effective piston area of 0.19 square inched, so the pulsed load is just under 400 pounds.

I think your decimal point is off for your effective piston area. ID of the gas key is only .025 sq in.

 

[MistWolf]

I think your decimal point is off for your effective piston area. ID of the gas key is only .025 sq in.

The areas being pushed by the gas is the back of the expansion chamber inside the carrier and the back of the bolt. Not the gas key.

 

[marksman13]

I’ve been shooting suppressed for a few years. Port pop is a real thing. Manually operated suppressed firearms don’t have port pop and are known to be quieter.

(No, I’m not suggesting anyone thumb the forward assist to hold the action closed.)

I’m not disagreeing that the rifle will be quieter if the action doesn’t cycle. I’m saying it’s not enough difference to matter in the given scenario. A neighbor whom can hear the action cycle is going to hear the crack of the bullet if using supersonic ammo or the gas escape the muzzle even if shooting subsonic ammo. Sometimes we get so twisted about making something as quiet as possible without considering how much that matters in the real world use of things. I refuse to shoot animals with subsonic ammo because I’ve seen too many failures to cleanly kill pigs/deer. I’ve never had a neighbor come see what I was doing.

I’ve shot pigs in an open field next to a highway while a highway patrolman was conducting a traffic stop a couple hundred yards away. Talked to said patrolman the next day and he said he heard something, but didn’t pay it much attention. He never equated the sound he heard to gunshots. 99.9% of the general public is going to have the same reaction.

 

[Scout21]

neighbor whom can hear the action cycle is going to hear the crack of the bullet if using supersonic ammo or the gas escape the muzzle even if shooting subsonic ammo.

I think I forgot to add he's using a heavy subsonic loading, I'd assume a 220 grainer. No idea what bullet, though. He's also shooting suppressed.

 

[lysanderxiii]

Mil spec bolt carries are most often cast from 8620 (this is a low carbon steel, ~.20% carbon). Steel with this low of carbon content cannot be hardened much past HRC45 with quench and temper or austemper heat treatments let alone nearly 60. Bolt carrier castings are machined to near final shape. They are then case hardened (surface carburized, heated in a high temperature and high carbon atmosphere and carbon is absorbed into the steel transforming the surface layer from austenite to martensite). This case hardening results in a surface that is typically HRC 58-62 but it only penetrates the surface of the part 0.010 -0.015 in the case of a bolt carrier (the process can be adjusted for less or more penetration). The core of the part remains relatively soft. The bore in the carrier that the gas rings slide on is then then ground to final dimension/finish. This soft core and hard out surface gives the part good wear resistance while not making the part a grenade in the event of a bolt carrier rupture. The soft core helps ensure you don't create many high velocity fragments in a failure (the same reason gun barrels are relatively soft and made from medium carbon steels and comparable stainless steels.).

If the forward assist is not mechanically stuck but simply held forward then remember as the bolt start to cycle backwards it will push the forward assist rearward and given the angled approach the forward assist makes to the side of the bolt carried it will eventually move to the side far enough to disengage the bolt carrier. Try it, hold the forward assist forward with a thumb and pull the charging handle, the forward assist with chatter under your thumb as it slips off each notch in the bolt carrier.

And the proper answer is no forward assist at all. Eugen Stoner was against it. Get a gas system with an off selection...

Sorry. No.

1) Carriers are not cast. Bolt carriers are made from AISI 8620, ASTM A108 or ASTM 322, which is a cold rolled bar stock.
2) All features on a carrier are machined in place. You can find Youtube videos of machining centers making them.
3) The hard surface can be chipped leaving the soft core, eg, a gear, made from 8620 and case hardened to approx 0.010" depth with a comparable surface hardness shown below. It the case shown, basically just the hardened case chipped off.
4) The chattering is what is most likely to cause chipping of the serrations.

 

[Scout21]

Has your buddy considered bow hunting?

You know, I hadn't even thought about that. Given that it's a rather small parcel of land I think I'd rather head shot them with a rifle, though. Less squealing, probably.

No clue if he knows how to shoot a bow, we've never spoken about it.

 

[mcb]

Sorry. No.

1) Carriers are not cast. Bolt carriers are made from AISI 8620, ASTM A108 or ASTM 322, which is a cold rolled bar stock.
2) All features on a carrier are machined in place. You can find Youtube videos of machining centers making them.
3) The hard surface can be chipped leaving the soft core, eg, a gear, made from 8620 and case hardened to approx 0.010" depth with a comparable surface hardness shown below. It the case shown, basically just the hardened case chipped off.
4) The chattering is what is most likely to cause chipping of the serrations.

View attachment 1081732

Doesn't matter if its cast or machined from bar. If its 8620 its 8620 and will have similar properties in either form and after carburization the difference will be even less relevant. 8620 was developed as a alloy specific for casting and case hardening. The fire control parts (trigger, hammer) are typically investment casts made with 8620 and then case hardened.

The answer is still to get rid of the forward assist all together, and install a gas system with an off setting it needed for super quiet suppress shooting. Or go to a manual action for supper quiet suppressed shooting.

 

[daniel craig]

Yeah, if the neighbor doesn't like guns or hunting, think how thrilled they'll be if an obviously shot animal dies on their property.

As far as holding an appendage on it, not me thanks, I like all 10 as they are. I read people put their thumbs over the back of just a .22 pistol slide, preventing it from coming back to stop the noise of it cycling, but I'm not brave enough to even do that.

Been through this. It's far from fun.

 

[daniel craig]

You know, I hadn't even thought about that. Given that it's a rather small parcel of land I think I'd rather head shot them with a rifle, though. Less squealing, probably.

No clue if he knows how to shoot a bow, we've never spoken about it.

There's also crossbows, if they are legal to hunt hog with it might not be a bad idea.

 

[Varminterror]

I’d be hard pressed - having experienced exactly what we’re discussing - to believe significant injury would arise from doing so. The FA isn’t positioned such the thumb is at it’s maximum extension, and the travel is short. Even if the roll pin fails, remember, we’re not talking about holding back the force of the cartridge bolt thrust, only holding the reciprocating force applied to the carrier… it’s a slap, and it smarts… not as bad as hitting your thumb with a hammer, but worse than the sting of a hard high five… Our hand isn’t positioned to have the thumb at maximum extension…

But we aren’t strong enough either to hold the FA from moving. Only enough to engage it. Which then allows partial travel of the carrier…

There are simply better alternatives - even those ready made to accomplish the task.

 

[herrwalther]

And the proper answer is no forward assist at all. Eugen Stoner was against it. Get a gas system with an off selection...

Stoner also wasn't a soldier. I have multiple incidents of two reasons why it is a good idea. On a silent brass check, the FA is used to make sure the bolt is fully seated. With making minimal noise. I do not not use the FA (as intended) to force a stubborn round in. I would rather just eject it and get a fresh one. The other is when Private Joe Snuffy forgets to put their buffer and spring back in after cleaning. That causes the carrier to get stuck in the buttstock, lodging the upper and lower together. This happened enough that I had a system for getting the bolt carrier just far enough forward to engage the FA on the notches.

 

[mcb]

Stoner also wasn't a soldier. I have multiple incidents of two reasons why it is a good idea. On a silent brass check, the FA is used to make sure the bolt is fully seated. With making minimal noise. I do not not use the FA (as intended) to force a stubborn round in. I would rather just eject it and get a fresh one. The other is when Private Joe Snuffy forgets to put their buffer and spring back in after cleaning. That causes the carrier to get stuck in the buttstock, lodging the upper and lower together. This happened enough that I had a system for getting the bolt carrier just far enough forward to engage the FA on the notches.

Nearly every weapon system currently in the US arsenal was designed in larger part by engineers that were not soldiers. For the same reasons you don't want the race-car driver to design the cam shaft for his engine or a pilot design the turbine in his jet.

I can and have accomplish both of your uses for the forward assist on rifles without a forward assist.

 

[herrwalther]

Nearly every weapon system currently in the US arsenal was designed in larger part by engineers that were not soldiers. For the same reason you don't want the race-car driver design the cam shaft for his engine or a pilot design the turbine in his jet.

I can and have accomplish both of your uses for the forward assist on rifles without a forward assist.

Vast majority of engineers do not take into account real world problems. The US Army wanted the FA because sh*t happens. JMB didn't think the 1911 needed a thumb safety or a grip safety. Army said put them on. It is entirely possible US arms evolution would have gone much different if both firearms were denied. My statement was not a declaration that only soldiers can design firearms. Soldiers can break anything. It is a common joke that if you give a piece of equipment to a group of privates, call it "indestructible" it will either be broken, or pregnant. Somehow.

By comparison, Mikhail Kalashnikov was a soldier in WWII prior to being the famed weapon designer he is known for. The AK was designed to be hard to break.

 

[Varminterror]

I use uppers with FA’s for all of my personal builds, if for no other reason than to aid in overcoming a sticky extractor which may decide to fail to clip over the rim, itself holding the bolt and carrier out of battery, and preventing operation/firing of the firearm.

 

[Varminterror]

Vast majority of engineers do not take into account real world problems.

While this sounds great online, it certainly does not have any founding in reality.

 

[mcb]

Vast majority of engineers do not take into account real world problems. The US Army wanted the FA because sh*t happens. JMB didn't think the 1911 needed a thumb safety or a grip safety. Army said put them on. It is entirely possible US arms evolution would have gone much different if both firearms were denied. My statement was not a declaration that only soldiers can design firearms. Soldiers can break anything. It is a common joke that if you give a piece of equipment to a group of privates, call it "indestructible" it will either be broken, or pregnant. Somehow.

By comparison, Mikhail Kalashnikov was a soldier in WWII prior to being the famed weapon designer he is known for. The AK was designed to be hard to break.

As an engineer by profession and one that has worked in the DoD world my entire career I would assert that your "Vast majority of engineers" is wrong. The engineers that do not take into account real world problem (DoD or otherwise) do not create many successful products and thus do not remain gainfully employed for long.

 

[Skylerbone]

I do think, at the very least we have come to a consensus that thumbing the FA forward is not a rewarding venture, may result in damage, will definitely sting a bit, and won’t be a practical solution for the proposed purpose. To that end I think the thread has successfully answered the question.