Some buffer questions

[Zeneffect]

Just a thought about port pressure...

15k-17k psi is seen on the barrel side of the port, what does the gas tube see? There is a pressure reduction when you have the smaller orifice/gas port and it seems everyone is skipping that calculation? I would think 15kpsi would rupture the gas tube near instantly wouldn't it? Pretty sure I've blown up stronger stuff with less pressure so the tube seeing 15k is questionable to me.

Not to say this has any bearing on the unlock time... but also the stated .5-1ms extra dwell in the scale of time we are looking at is quite a decent amount for the pressure to drop. Extra 1% or so of additional time scales out on the pressure side to thousands of psi of chamber/gas pressure

All that being said, I run a super42 spring and h2 buffer with no adjustable gas block on all my carbines. Cyclic rate is perceivably slower, and it just flat out runs without issues so I don't touch the setup. Sometimes I wonder if I went the opposite direction what that would be like (light buffer, spring, carrier, minimal gas)

[LRRPF52]

I think the happy window of operation for the expansion chamber inside the carrier is 2000-2200psi with a Mil-Std M16 carrier weight.

[montana]

You would be correct about the reduction of pressure entering the gas key..The barrel port pressures were an unknown in the early days as Colt, Stoner/Armalite or Remington never had a way to measure them..It was Springfield armory who first invented a way to measure port pressure..The lack of port pressure specs is what caused the problems when ball powder was first accepted for use..The cycle rate and fouling were the main concern when they first were considering a switch to ball powder..Colt's very capable engineer Foster Sturtevant made a very bad claim he would later regret when he first stated the extra port pressure would make the M16 more reliable.. Barrel port pressure for ball powder could accede 17500 lbs while staying well within the safe chamber pressure spec..When shorter barrels and gas port locations come into play, the burn rate changes drastically, creating a much higher residual pressure curve..

In one of the graphs, the lightest buffer had a longer lock time than the heavier ones..My main point is it is the residual pressure that is effected by buffer weight and spring tension, not the bolt un-locking cycle..Even Stoners claim that the higher port pressures with ball powder caused the bolt to unlock prematurely (as the case was still expanded to the chamber wall) that caused the catastrophic stuck cases, ripped off rim malfunction has been dis-proven..It was the lax case hardness in pitted chambers that caused these extraction problems..

[grayfox]

[Happy2Shoot]

I learned a few things from Lantac.

1 The majority of the gas comes out before the BCG moves.

2 No gas comes out of the chamber after the BCG moves.

Therefore, I no longer believe extra mass buffers help with educing gas to the face.

https://www.lantac-usa.com/e-bcgwhitepaper

[KC_Joe]

Following up here.....

I just could not get the flat wire springs to stretch or wiggle onto the factory buffer. Packaging said .75" inside diameter, and the top of my buffer was just a little too large. I replaced the factory spring, and decided to pick up the Odin adjustable buffer.

Decided to start with 4.0oz and see what happened.

We've had recent cold temps, but today was in the 20s so I decided to give it a try. As was recommended, I closed the gas block such that no cycling of the bolt occurred, and opened 1 click at a time until proper function. I settled on 6 clicks and everything functioned without issue. The "slap" seems to be gone, and I think I'm happy with things.

After another range trip I should have 200 factory rounds down the barrel, and will start some load development. Planning to load 123gr SST over H335 and see what I get. Will also keep the gas tube wrench handy in case reloads aren't quite as hot as the factory rounds.