My 2nd review of the Primary Weapons piston conversion

[militarymoron]

thanks robb. i had yet to figure out whether bone dry or a light coat of machine gunners lube (or even sentry solutions dry lube) was better to use on the piston, and which one is easier to clean up carbon deposits on later.

my printed manual has the 'not for anal insertion' warning.

[sniperfrog]

gotm4 and militarymoron,
Were your gas block screws staked like PWS is advertising now? If not, do you feel staking the gasblock will hold as good as taper pins?

[Robb Jensen]

gotm4 and militarymoron,
Were your gas block screws staked like PWS is advertising now? If not, do you feel staking the gasblock will hold as good as taper pins?

To be honest I don't think staking will do much if anything at all. Nothing beats pinning which is why it's in the TDP. Crane recalled MK12s because set screwed gas blocks shot loose in the field and in combat on direct inpingment guns and Crane pinned them, 'pinned is the way' for gas blocks/FSBs anyone who tells you otherwise should be considered a poor source for information on the AR.............Well maybe MIG welding the gas block to the barrel would be stronger but then it would also be permanent.

[ARin]

mine are double staked.

havent loosened yet, but then again, im only a few hundred rounds in at this point.

[militarymoron]

mine weren't staked so i staked them myself. this was probably just in case any adjustments needed to be made as i was one of the willing guinea pigs/pre-production testers.

[militarymoron]

i posted a vid shooting my PWS upper:
http://www.youtube.com/watch?v=1Z3xiyuzzps

[SuicideHz]

Kel you seem to be getting less recoil out of the PWS than the HK. Is that because of the brake or the actual piston systems?

[militarymoron]

(not kel), it's not an apples-apples comparison as my PWS is a 16" midlength system, and the 416 was a 10". and yes, i'm sure the FSC556 brake has something to do with it as well.
as for piston vs DI, the 416 definitely felt like it had a sharper recoil impulse than the 10.5" LMT CQB MRP upper, which didn't have a brake on it.

[superman07]

I picked up a 16 in PWS upper and so far it is running very well. I am a bit worried as the gas block is not pinned as many have suggested may be ideal. How much custom gunsmithing is required to make this happen?

I guess I would rather be proactive then assume I will not have a issue. Would running the heavier buffers place more stress on the rods and gas block? I would think the energy required to begin moving the heavier weight rearwards would make a sharper impact on both.

[Robb Jensen]

I picked up a 16 in PWS upper and so far it is running very well. I am a bit worried as the gas block is not pinned as many have suggested may be ideal. How much custom gunsmithing is required to make this happen?

I guess I would rather be proactive then assume I will not have a issue. Would running the heavier buffers place more stress on the rods and gas block? I would think the energy required to begin moving the heavier weight rearwards would make a sharper impact on both.

I'm using a H2 weight Seth Harness anti-tilt buffer with mine. When I used a H buffer or H3 buffer the rifle recoiled more than it does now.

Any decent machinist or good gunsmith could taper pin the PWS gas block. I did mine with a drill press and reamed it by hand. It was very time consuming because I had to go at it at a slight angle to avoid the factory Colt taper pin hole in the barrel. I reamed it by hand with a hinge pin reamer and it's held up fine. If I were to do mine today I would drill/pin it higher up near the top of the front edge of the gas block to avoid the taper pin holes on the bottom of the barrel. This would be much easier using a milling machine to mill a flat spot and then drill a 1/8" hole through both the gas block and barrel at the same time. Then ream it by hand and install a standard Colt taper pin or use a straight pin at least 1" long.