barrel is 8.5 inches. I drilled the gas port a little farther back, so I could cut an extra half inch off the barrle if I want to (to crown it better maybe) and still have the factory specs on port to muzzle.
Receiver is an OOW, I moved the rear trunion forward about 3/4", I had to remove some metal from the bottom middle of the trunion, and from the grip nut, so they would not interfer. grip nut is permanent [+]:D Dremmeled the rails for the bolt carrier, didn't touch the rails where the bolt head goes in, (so it fits together like a saiga 308 TIGHT, with a wiggle)
I ran a rivet through in the back, jus tin front of the trunion. welded a sling loop to the rivet, instant swivle.
I plan on modifying a grip to fit the shape of the shorter rear receiver, maybe
front handguard, I cut out some clearance slots for the gas tube screw. I also welded a flat plat on the handguard, at the rear, to fit inside the receiver, I put a bolt through the receiver, into the flat plat, so my handguard can be freefloat. However, I also took the old retainer, and added some weld inside it, and slipped it on, then drilled through it, and I just put a long 3/16 through it, and bent it over. So, it's semi permanent. But I ahve lots of rivets. And the gun can be disassembled with the handguard in place,
Gas tube... spent a lot of time on this. I drove a 11mm socket through it witha bfh and a blow torch. then I cut it down so it fit onto the piston, all the way to the bolt. it took a lot of trial and error. and every time I welded onto the gas tube, the weld leaked through microscopicaly and warped the metal inwards, so I had to drive that socket through a few more times as I fitted thing.
I welded a new "sight block" to the gas tube, threaded the bottom hole and added a spot of weld to the barrle, to hold the gas tube down and forward. The handguard interacts by holding this piece up. So, this baby is on there good. I am thinking about adding to the barrle, add a screw hole there, so I can screw the gas tub dirrectly to the barrel. but it's good for now.
Took the bolt carrier, screwed out the piston, cut the tip off, ground off some chrome, and welded it back to the carrier, very shorty, also drilled it and put a rivet in, just to be sure.
Had to grind down the new "opperating rod/carrier" a little, around the circumference of the piston, to make things fit perfect during final assembly.
the receiver cover is not shortened over all length, but I trimmed the ports to reflect the change in the rear trunion.
I added a buffer, made of tire sidewall, and bake on ceramic coated it, last night, and cooked it in the oven, while the parents are on vacation... HAHAHAHAH
time to go test fire it again. I forgot to cut out the ejection port on the cover, so it had a few stovepipes. Without the receiver cover, it was a champ though... and I could feel unburnt powder hitting my face.
With glasses on, it was only annoying.
So, with the rubber in there, the action is even shorter, and bounces back Lighter bolt, and the gas port is factory size, but only 6 inches from the breach.. that's four inches fom the bullet.... so bad!
the cyclic rate should be much higher, yes?