Which gas block for suppressor

[Mebe007]

I appreciate all the info guys. All good stuff. as we know I have time to make the decision. What is everyone running for buffers? my buddy has an 18" grendel with the 1st gen tbac 7 and the superlative block. he is successfully running the carbine buffer. he was way overgassed before switching to the adjustable gas block and i believe was running the h3 buffer.

also I do handload

[Happy2Shoot]

i notice you are in VA, as am I. Why the recommendation to switch to an H3 buffer? im really excited to get the wait over on the can but it just started today lol. Long wait ahead.

A silencer increases the time it takes for the gas to exit. That's it.

Increased mass of the BCG and buffer system, increases inertia of the system, inertia is the resistance to change in movement.

Every millisecond you can resist opening the chamber is time for gas to go out the muzzle, and not come out the chamber at your face.

Every millisecond you can resist opening the chamber is time for gas pressure to drop in the chamber, and not come out as loud in you ear.

Also, slower extraction due to lower port pressure reduces bent or ripped case rims.

The buffer spring doesn't do anything here because you have to compress the spring a great distance to make a difference and by then the chamber is already open.

[Happy2Shoot]

Also, incase you didn't know always wear ear protection when shooting a supersonic cartridge.

[montana]

A silencer increases the time it takes for the gas to exit. That's it.



Every millisecond you can resist opening the chamber is time for gas to go out the muzzle, and not come out the chamber at your face.

Every millisecond you can resist opening the chamber is time for gas pressure to drop in the chamber, and not come out as loud in you ear.

Also, slower extraction due to lower port pressure reduces bent or ripped case rims.

Not exactly true. In May of 1964, Bill Davis (the AR-15 ammunition project manager) left Frankfort Arsenal and started working at Colt as XM16E1 Engineering project manager..While at Colt, he discovered Colt had done some kinematic studies that substantiated the closing velocities of the AR-15 studies he had obtained from Springfield Armory.. Colts new heavier buffer invented by Colts chief product engineer Forest Sturtevant was 3 times as heavy as the original Edgewater buffer..They discovered the new buffer's added weight on the dwell time or bolt opening cycle was (negligible)..

Complete rim shear with cases of acceptable hardness very seldom happens..

[LRRPF52]

One thing to remember is the more slop between the bolt's boat tail and the carrier's bolt tail bore, the more gas will be felt in the face..Suppressors will only intensify this..

You will see more soot in the FCG with an inefficient carrier like that.

I don’t use bolt carriers if they are loose like that, which is one of the more important call-outs in the TDP.

Most manufacturers don’t pay attention to this, and just crank parts out the door.

[LRRPF52]

I have noticed a difference in cyclic rate and overall feel of the cycle of operations when using different action spring weights/lengths.

Stiffer springs help tame the cyclic rate, especially when shooting suppressed.

They can be rifle, carbine, or even pistol-length springs, but as long as they are stiffer/extra power, they will reduce the initial carrier velocity to the rear, then deliver more positive feeding and going into battery.

One of the best-running set-ups has been with the tiny pistol RET, a short/stiff pistol action spring, and tiny pistol-length buffer that still weighs 2.9-3.0oz.

Unsuppressed, that configuration would not cycle with 90gr TNT factory ammunition though, even with CLGS, 12” barrel, Bootleg run fully open (no choke/normal).

Once I attached the suppressor, it ran like a raped ape through all 4 gas choke settings, with the best performance on fully-choked.

For RLGS 20”, your port pressure will be much, much lower, but the gas port cut in the barrel is larger (should be .094”).

When you attach an accumulator on the end of a 20” barrel, it will act as additional barrel length and often cause early unlocking if you don’t choke it.

The TBAC Ultra 5 actually works surprisingly well on a 20” Grendel, close to Hollywood quiet.

On 12”, it’s pretty loud, whereas the Ultra 7 really tames the 12”.

[montana]

You will see more soot in the FCG with an inefficient carrier like that.

I don’t use bolt carriers if they are loose like that, which is one of the more important call-outs in the TDP.

Most manufacturers don’t pay attention to this, and just crank parts out the door.

Yup! Another sign is a bent retaining pin (cotter key) for firing pin..

[Happy2Shoot]

Not exactly true. In May of 1964, Bill Davis (the AR-15 ammunition project manager) left Frankfort Arsenal and started working at Colt as XM16E1 Engineering project manager..While at Colt, he discovered Colt had done some kinematic studies that substantiated the closing velocities of the AR-15 studies he had obtained from Springfield Armory.. Colts new heavier buffer invented by Colts chief product engineer Forest Sturtevant was 3 times as heavy as the original Edgewater buffer..They discovered the new buffer's added weight on the dwell time or bolt opening cycle was (negligible)..

Complete rim shear with cases of acceptable hardness very seldom happens..

1964 measurement equipment was probably unable to measure half a millisecond, and yet the difference between a pistol length and a rifle length gas port is less than half a second.

[montana]

1964 measurement equipment was probably unable to measure half a millisecond, and yet the difference between a pistol length and a rifle length gas port is less than half a second.

I never disputed port pressure or the placement of the port on the barrel effecting dwell time.. It is the belief the buffer weight has more effect on dwell time than it actually does.. Buffer weight effects the bolt carrier velocity, not the dwell time..This is why I'm an advocate of an adj gas block to find the sweet spot for different ammunition.. The heavier buffers were necessary for bolt bounce malfunctions, especially with heavy barrels ..Malfunctions also occurred when the bolt carrier cycled so fast the magazine failed to push the next round into proper position..The Colt M-4 solved this problem when they cut feed ramps into the upper receiver. They then created the heavier H-1 buffer that made the Upper receiver ramp cuts redundant.. The upper receiver ramp cuts were one of the reasons FN has to pay Colt royalties when they make the M-4 for the military.. Colt developed the M-4 with its own funds and owns the rights to the M-4 TDP..

[montana]

To be more clear about this subject, dwell time is separate from bolt velocity..

Proper dwell time is determined by the powder-bullet, port size-location on the barrel..The weight of the buffer has no effect on dwell time..

The buffer weight determines how fast or slow the bolt will try to lock-unlock and cycle..

[PNWTargets]

I’m a nerd when I comes to design and function. Definitely spring and buffer weight affect the cycle function of BCG in relation to the gas system and flow.

Good recommendations here. All components affect each other.

BCG speed, travel, and dwell are what we are all trying to mess with.

I even look at dwell time from when fire pin hits primer and the BCG starts to move. Weight and spring rate affect this. I want to hold as much gas pressure as I can from when fire pin hits to when BCG fist moves.

[montana]

I’m a nerd when I comes to design and function. Definitely spring and buffer weight affect the cycle function of BCG in relation to the gas system and flow.

Good recommendations here. All components affect each other.

BCG speed, travel, and dwell are what we are all trying to mess with.

I even look at dwell time from when fire pin hits primer and the BCG starts to move. Weight and spring rate affect this. I want to hold as much gas pressure as I can from when fire pin hits to when BCG fist moves.

The dwell time is when the bullet passes the gas port charging the system until the bullet exit the barrel..Using a suppressor increases dwell time.. The buffer or spring weight has nothing to do with holding gas pressure..

[PNWTargets]

The dwell time is when the bullet passes the gas port charging the system until the bullet exit the barrel..Using a suppressor increases dwell time.. The buffer or spring weight has nothing to do with holding gas pressure..

BCG dwell is when the BCG moves from static (back/forward). Spring pressure does affect this dynamic movement. When the BCG is still static as gas flows to it, that has to do with holding gas pressure. Possibly I am not explaining what I mean clearly.

[montana]

BCG dwell is when the BCG moves from static (back/forward). Spring pressure does affect this dynamic movement. When the BCG is still static as gas flows to it, that has to do with holding gas pressure. Possibly I am not explaining what I mean clearly.

The dwell time is the length of time the gas system is charged, period.

Bolt cam tract length (lock time).
Pressure curve (powder or bullet type)
Barrel port size (amount of pressure)
Bolt carrier resistance (force needed to move the carrier and bolt to cycle)

Timing of these variables are critical to function..Make changes to any of these variables and malfunctions can occur..

Moving the location of the barrel gas port will change the dwell time ( the amount of time the gas system is pressurized).
Change the spring-buffer-carrier weight, will change the cycle resistance to gas pressure..
Change the bolt cam tract and lock time changes..
Change the powder or bullet type and the pressure curve changes..
Open or shrink the gas port and the amount of pressure changes..
This is why they discovered the new buffer's added weight on the dwell time or bolt opening cycle was (negligible)..What it did do was slow the cycle rate (bolt carrier velocity) and prevented bolt bounce..
This is why locating the gas port farther from the muzzle will result in a longer dwell time and a gas port near the muzzle will have a shorter dwell time.
Adjustments are made all the time to the AR function with the gas system by opening or shrinking gas ports, gas port locations, buffer springs, weights and carriers and even different bolt cam tact time length..

When the bullet passes the gas port the system is charged, even in the bolt carrier. The Stoner internal piston will actually push the bolt forward while the system is charged away from the locking lugs in the barrel extension, relieving stress on the bolt, while simultaneously pushing the carrier the opposite direction . The bolt will not unlock or the carrier cycle until the port pressure has dropped after the bullet has left the barrel..The residual pressure in the system cycles the bolt carrier..The heavier the buffer, the slower the bolt carrier cycle (velocity) occurs. The lighter the buffer, the faster the carrier cycles (velocity) occurs..The dwell time is the time the system is charged..

A good example of dwell time is an air hose. If you have one length of hose and charge it with 120 lbs of air the system is charged with 120lbs. Disconnect the hose and the residual air escapes. Now hook up 3 lengths of the same hose and do the same. It will take a longer time to expel the residual air, even though it also has the same 120lbs of air. That is dwell time..

[montana]

Here is a description from the Aberdeen Proving Ground ballistic research laboratories:

The pressure variation with time at determined by the gas flow in the barrel.The mass flow through the port is small compared to the mass flow in the barrel itself,and the effect of mass removal is negligible on the pressure history at the port.Thus, the pressure and temperature may be considered prescribed and known, say from an interior ballistics analysis of the weapon.The hot gases expand in the bolt cavity, thereby accelerating the bolt carrier,C.Unlocking of the bolt, D, is accomplished after the carrier has traveled a certain distance, at which distance vent holes are laid free sad the gas in the bolt carrier expands to atmosphere.At this distance the bolt carrier engages the bolt and cartridge, and extraction is accomplished by transferal of energy and momentum of the carrier to the bolt and cartridge.

(The residual momentum and energy of the bolt carrier is sufficient to complete the cycle of cocking the weapon and positioning a new cartridge in the chamber.)

It is the object here to predict for a given pressure and temperature at the port the motion of the bolt carrier referenced in time to the rise of pressure at the port.The motion of the bolt carrier is governed by the pressure and temperature in the bolt carrier cavity.



This is what I have been trying to explain, the buffer-spring weight only controls the bolt carrier velocity(energy) and does not contribute to dwell time..

[Bonas]

I only use adjustable blocks on ARs now. I see no reason not to. The last one I installed was the Strike Industries adjustable collar block. I like it, and it works well so far. Next, I'll likely try the RifleSpeed.

https://www.strikeindustries.com/si-ar-cagb.html

[Bonas]

I only use adjustable gas blocks in ARs now. Last time, I used the Strike Industries adjustable collar block. It works well so far, and I like it. I'll probably try the RifleSpeed next. Much of my shooting is suppressed.

https://www.strikeindustries.com/si-ar-cagb.html

Maybe it's irrational, but it I like the idea of excess gas never getting to the tube, so I use the block as the choke point. We're finally getting some well-designed options.