When I designed the Short Muzzle Brake for M14.CA, I started with experience at THREADING dozens of different types of muzzle devices on to shortened M14 barrels, cut, crowned, and threaded to AR 15 type 1/2" x 28 tpi threads. AND, shooting these various devices in fast, multiple shot type scenarios, to determine which gave the best COMPROMISE between controlling muzzle flip, recoil, flash, and blast.
Any muzzle device can only go so far towards eliminating these often mutually contradictory characteristics. The blend of these often opposing traits, is what gives a particular muzzle device a certain "feel". With the M14.CA short comp, I got the "feel" I liked, and a short barreled M14 fitted with this device , shooting full power 7.62 NATO ammo, "feels" similar to shooting an SKS firing 7.62x39 RUSSIAN ammo. The reduction in recoil and muzzle flip is significant, and the increase in blast and flash is also significant. NO FREE LUNCH IN PHYSICS ... there must be some trade offs.
THEORETICALLY, a shortened barrel cut between 18.5"and 20", will.have more RESIDUAL gas pressure at the muzzle than a 22" barrel, and I optimised the ports / gas flow for these shorter barrels. However, any muzzle device, short of tying an anvil on to the barrel, will have only limited success. We tested various port shapes and sizes for muzzle rise, resting the forend on a padded block, forend UNSUPPORTED and unemcumbered, with graph paper behind and a video camera to measure rise. Not overly complicated or sophisticated, but this got us in the ball park. The muzzle rise was reduced "significantly".
BUT,
EVEN GREATER REDUCTION IN MUZZLE FLIP was noticed by changing the stock to a more modern, ergonomically more efficient design, with the butt moved upwards to give a straight line thrust back directly from the bore, with no leverage "vector force" trying to rotate the rifle upwards. And adding a pistol grip, while not directly changing the thrust line, with a proper firm grip, could DIVERT some of the recoil forces into the grip hand, for improved CONTROL.
In my experiments, a properly designed stock, with pistol grip and straight line thrust, provides more recoil control improvement than any muzzle device ( short of an anvil).
There are some very good reasons why the AR 10 has less felt recoil and muzzle flip than a conventionally stocked M14. AND, if you are shooting rapidly, in other positions than off the bench or bipod, this reduction in recoil and muzzle flip, and improved control for fast follow up shots, is even more obvious.
PS: If you really want to get kinky, the M14.CA muzzle device is a two part design, so with the sight tower set to ERTICAL, the ports can be rotated slightly to offset the usual tendency for fast follow up shots from a right handed shooter to string "high AND RIGHT" . Tightens up.your double taps. But that is probably a bit more than any normal person ( except the HI SPEED/ LOW DRAG TYPES ) really needs.
PPS: EVEN BETTER, use 110 or 125 gr bullets, perhaps at lower velocities.
Combining all these tricks and tweaks can result in an M14 that is as fast to shoot as an AR 15, although it will still be pounds heavier. BUT, you can still shoot FULL POWER .308 WIN/7.62 NATO if required.
BTDT
which is why I think the M14 is possibly the most VERSATILE rifle ...
EVER!