Larue Ultimate Upper Gas Block Question

[Vetman1]

Has anyone switched out the gas block on a Larue Ultimate Upper kit for an adjustable gas block? I am running Silencerco Hybrid suppressors on my two uppers and I am getting a lot of gas blow back. The guns run so smoothly I am hesitant to mess with their function.

Currently though, the ammunition left in my magazines are really dirty after just a couple shots.

[LRRPF52]

I would drop in a Bootleg adjustable carrier and maybe a heavier buffer.

There are 4 gas setting on the Bootleg that can be accessed through the ejection port with a flat head.

[Kswhitetails]

I would not remove the gas block unless I really had to. They use some special pixie dust during assembly that flies away when you start taking them apart.

Seriously though, don't change it unless you have to, I like the idea of the adjustable key or carrier here.

[Klem]

Unfortunately that's what happens when you suppress an AR. The suppressor keeps pressure in the barrel for longer and when the brass seal is cracked during extraction it all comes back around the case. The spit and crud is coming from the chamber not the gas system and it doesn't matter what gas system or setting you use, the back pressure from the chamber will always be there. The good news is that a coating of carbon on the top rounds in the magazine is cosmetic only. it doesn't affect accuracy. If you hand-load then unfortunately the dirtier cases means extra cleaning, but that's one of the costs of suppression.

What position on the clock face are your spent cases being ejected?

[Vetman1]

The shells are kicked all the way to 4 or 5’ o’clock position. The rims have what looks like ejection marks on the cases. I am shooting factory loaded Hornady 123 grain SST.

I know that companies love to push propaganda, but would the adjustable gas block help reduce the recoil on this gun? My 10 year shoots one of the Grendel uppers and he only weighs 72 pounds.

Also, speaking with Larue they claim that the uppers are set up to run with their suppressors. They claim their suppressors let more gas out than other suppressors. Go figure.

[LRRPF52]

The shells are kicked all the way to 4 or 5’ o’clock position. The rims have what looks like ejection marks on the cases. I am shooting factory loaded Hornady 123 grain SST.

I know that companies love to push propaganda, but would the adjustable gas block help reduce the recoil on this gun? My 10 year shoots one of the Grendel uppers and he only weighs 72 pounds.

Also, speaking with Larue they claim that the uppers are set up to run with their suppressors. They claim their suppressors let more gas out than other suppressors. Go figure.

Yes, LaRue engineered their own flow-through suppressor to minimize gas pressure accumulation in the action.

Even their 18" MLGS Grendel runs optimally when suppressed with the Tranquillo.

LaRue posted pics of the test instrumentation that was involved with the design for the Tranquillo, and back pressure accumulation was one of the main issues they were addressing with that can.

[Kswhitetails]

With your UU order number you qualify for both a lower and tranquillo discount. With the discount, it more than covers the tax stamp. If they have discontinued the discount, disregard.

[HuntTXhogs]

You should definitely go adjustable and yes it helps with recoil

[Klem]

You should definitely go adjustable and yes it helps with recoil

With respect, I would be cautious suggesting an adjustable gas helps with felt recoil at all. It manages the energy by which the BCG is thrust to the rear but that's about it. Truth be known there is more felt recoil the more you restrict the gas when you want to tame it. Turn it off completely and there is no rearward movement of the BCG to absorb some of the recoil...you receive the full felt recoil. If you want to tame felt-recoil you are probably better off going lighter loads, muzzle brakes, suppressors, heavier barrels and shooting standing, sitting or kneeling (more of the body shares the recoil as it flexes).

[HuntTXhogs]

I Subscribe to the K-I-S-S theory

You’re right by all accounts that the items you mention are also contributory to felt recoil - I agree !

My point is this: when you run a rifle stock as the factory put out, each rifle is it’s own animal, with a non adjustable gas block you are stuck at that amount of gas being sent down the tube to the BCG.

Given no changes elsewhere you can expect that same amount of gas on each trigger squeeze.

What if - the amount of gas at the factory setting is more than what is needed to effectively cycle the gun??? I’m driving at the factory setting being overgassed ...

How would it NOT lessen felt recoil to tune that gas amount to the minimal amount needed to push the BCG at the optimal level ?

No doubt you’ve not changed the recoil impulse of the gun/cartridge but you sure have changed how much is transferred down the tube to the BCG hence the shooters shoulder.

In final, it isn’t the end all be all method but it can contribute to lesser felt recoil

[Goebela3]

Sounds like a good excuse to get the larue silencer. I just ordered the ultimate upper kit, how long did your take to come in?

[Kswhitetails]

Ha! my suppressor came in way before my rifle did. I think it was 4 days. They forgot to notify me or my guy it had shipped, my Class 2 called me and said, "UMMMMM IVE GOT THIS THING HERE WITH YOUR NAME ON IT, I WASN'T EXECTING ANYTHING?" Lol it was fun. And they were very glad for the paperwork...

With your UU order number, you can get the discount on the Tranquilo from Larue. Call them to place the order. Can't be beaten for that money.

[Klem]

I Subscribe to the K-I-S-S theory

You’re right by all accounts that the items you mention are also contributory to felt recoil - I agree !

My point is this: when you run a rifle stock as the factory put out, each rifle is it’s own animal, with a non adjustable gas block you are stuck at that amount of gas being sent down the tube to the BCG.

Given no changes elsewhere you can expect that same amount of gas on each trigger squeeze.

What if - the amount of gas at the factory setting is more than what is needed to effectively cycle the gun??? I’m driving at the factory setting being overgassed ...

How would it NOT lessen felt recoil to tune that gas amount to the minimal amount needed to push the BCG at the optimal level ?

No doubt you’ve not changed the recoil impulse of the gun/cartridge but you sure have changed how much is transferred down the tube to the BCG hence the shooters shoulder.

In final, it isn’t the end all be all method but it can contribute to lesser felt recoil

Recoil and felt-recoil are related but two different concepts. As long as you use the same ammunition recoil does not change regardless of how you adjust your gas. Recoil is the rearward force which is the application of Newton's third law of physics. As the bullet goes forward there is an equal an opposite reaction and there's nothing tweaking your adjustable gas system can do about it. 'Felt recoil' however is how much of that recoil is felt by you and this is what shooters are concerned about. Felt recoil is influenced by how much recoil is absorbed by the weight of the gun and the rearward movement of the BCG. Also influenced by if you can smooth out the impulse so a short sharp shock of recoil feels more forgiving if it occurs over a longer time.

I agree, that if you impart more rearward force into a BCG when it eventually comes to a stop that force will oppose more recoil than if it moved just enough to cycle properly. But, it will bash around your action more than necessary. Relative to other calibres the Grendel is not savage recoil, even in a light weight AR. Why then would you prefer your action to get bashed by more gas than necessary for a small reduction in recoil you are unlikely to even notice?

[Vetman1]

Klem,

Are you saying that an adjustable gas block will actually reduce the rearward force of the bolt and therefore it will be better for longevity of the rifle? If the bolt is not being forced back no more than needed to cycle the action is that better on the overall rifle?

Concerning recoil, I initially ran the Larue upper on a lower that had a JP silent Capture spring. I was using a Pulsar Trail Scope on this rifle and would have a bad pixel every 3rd of 4th shot. Since I went to the Larue buffer and spring I have not had another bad pixel. In this case a change in the recoil and felt recoil seemed to be better for my scope.

Also, I have been researching the Larue TranQuilo suppressor. It does allow more gas out the muzzle end than a typical suppressor therefore reviews say that the TranQuilo suppressor is not as quite as similar 7.63 suppressors. It is also heavier than my Silencerco Hybrid so I need to evaluate that as well.

[am4966]

Ha! my suppressor came in way before my rifle did. I think it was 4 days. They forgot to notify me or my guy it had shipped, my Class 2 called me and said, "UMMMMM IVE GOT THIS THING HERE WITH YOUR NAME ON IT, I WASN'T EXECTING ANYTHING?" Lol it was fun. And they were very glad for the paperwork...

With your UU order number, you can get the discount on the Tranquilo from Larue. Call them to place the order. Can't be beaten for that money.

Now you only have a year or so till you can take home. Boo lol