by gunnut » Fri Aug 26, 2011 9:43 pm
Recoil and Muzzle brakes.
I’d like to point out that there are 3 recoils in the AR rifle.
1st or primary. Newton’s laws. Action & reaction, a body stays at rest until acted upon.
This one is the cartridge igniting and propelling the bullet down the barrel and the rifle to the rear. This happen in .005 seconds or less. This is when recoil reducers work by forcing the rifle to compress a spring or other material in order to accelerate the counter weight in the reducer, slowing acceleration. Weight, travel and compression rate all come into play.
2nd. Secondary or rocket effect. This is the hot gasses exiting the barrel after the bullet. The gasses expand and accelerate at 3 to 5 time muzzle velocity, further accelerating the rifle. The smaller the bore the greater the velocity, Larger bore, less velocity.
This is where muzzle brakes come into play. For a very brief moment “.001 Sec.”The gasses are allowed to escape through port in the brake. Depending on where they are directed determines the effect of the brake. Up pushes the muzzle down helping to keep on target. The Izzy works best for this”. To the rear reduces recoil. “And blows stuff off the bench including what were friends”. To the sides, not much effect on big bores, maybe effective on smaller bores.
Getting these 2 to work together proved to be a problem. But, not impossible.
As the rifle is accelerating under the primary recoil the reducer is working. Once the bullet passes a recoil reducing brake the recoil reducer stops working because the brake has slowed the rifles acceleration. Travel and compression rate adjustments solved the problem.
3rd. Bolt, Carrier, Buffer and Spring reaching end of travel. What to call this?”BCB maybe? It’s very interesting to find out what is going on with this group of part.
When the bullet passes the gas block about 40kpsi goes down the gas tube into the bolt carrier. For a brief moment the bolt is slammed forward into the full locked position. “It’s lighter than the carrier” Then the carrier is propelled to the rear unlocking the bolt and the accelerating rifle mass just got about 12ozs lighter. At this point most of the recoil is dissipated. The bolt carrier and buffer are acting the same as a recoil reducer but opposite.
The 12ozs mass is being decelerated by the spring reducing the recoil when they reach end of travel.
I have not tested any buffers yet and there are a few other interesting things about the bolt carrier and buffer.
Sorry to be so long. Just trying to sum up what I have learned so far and I know I’ve left out a few things.
Happy Shootin!