just started 7.5 build

[Sumsky]

I do use a Levang comp. I'm sure that gives a certain amount of back pressure.

I plan on using the Primary Weapon System CQB Comp. My Cousin uses one on his duty AR and he says its great, throws everything forward. Which Gasblock did you use? That could also be an issue depending on the opening in the Block.

[shadow65]

I'm glad you asked about the gas block. I bought the Rainier Low Pro stainless gas block and had it pinned to the barrel by them before shipment. Very tight which I'm sure also contributes to the cycling of the 7.5"
I called Rainier and asked about the gas port before I bought it. They told me it was .056. I expressed my concern about it being so small. It's the same they use with thier builds.
I was pretty convinced it wouldn't work but I talked to some other guys that had the same barrel and it ran great for them. So I gave it a shot. Couldn't be happier. Accuracy is good also.
I've not done any real testing for groups yet (just too many other things to test for other manufactures) but I ran some .22 Aguila 60 gr. through it with a CMMG conversion and was keeping the shots in a 3/4" dot at 25 yards with a scope.
If it will do that with .22 and a conversion, .223 should do great.
Dave

[Sumsky]

I'm glad you asked about the gas block. I bought the Rainier Low Pro stainless gas block and had it pinned to the barrel by them before shipment. Very tight which I'm sure also contributes to the cycling of the 7.5"
I called Rainier and asked about the gas port before I bought it. They told me it was .056. I expressed my concern about it being so small. It's the same they use with thier builds.
I was pretty convinced it wouldn't work but I talked to some other guys that had the same barrel and it ran great for them. So I gave it a shot. Couldn't be happier. Accuracy is good also.
I've not done any real testing for groups yet (just too many other things to test for other manufactures) but I ran some .22 Aguila 60 gr. through it with a CMMG conversion and was keeping the shots in a 3/4" dot at 25 yards with a scope.
If it will do that with .22 and a conversion, .223 should do great.
Dave

Dave, thanks for all the helpful info. I would be a fool to try and re invent the Wheel when its already perfected. I am going to use your build as a guideline. Now to try and convince my Cousin about what you said.

[Sumsky]

Dave, I had told my cousin about the Ranier 7.5 set up with the smaller Gas Port. He figured out why it works. The Tapered Proprietary Gas Tube and the slower 1/8 twist rate. What do you think?

[shadow65]

Could be. I know the rifle doesn't get dirty as fast as other 7.5" uppers I've had. Recoil isn't bad either.
The Levang makes it feel like more of a push.
Dave

[Nanuk68]

I built a 7.5'' PDW pistol with the Rainier 7.5'' 1/8 SST. It runs on a BCM upper w/bcg and YHM lopro gas block. Runs like a dream. I'm going to be sending in my papers soon to make it official. Wouldn't hesitate to do it again.

[shadow65]

I knew it would. Great to here. SBR that puppy.
Dave

[axeeclipse]

Dave, now I am curious about the size ports on the Noveske. Anyone here on the Forum know what size port Noveske uses on the 7.5 Barrels?
How the heck did Ranier get their 7.5 to run on .056 opening, thats amazing, and you said you are running regular size Buffer and Carrier. I might have to go with a Ranier 7.5. I have read that the smallest you could go is a .062. Your DPMS is a 7.5 with a .078 opening, thats large. You should do a test and see how many rounds you can go without cleaning, you dont have to shoot 500 rounds in one day, just keep count each Range visit, and dont clean the Gun. I am curious.

I have put 500 rounds of wolf through my dpms 7.5" sbr and had only 3 hiccups towards the end. And ballistics wise, ive hit steel man sized plates at 450 yards with mine. Sure it may not drop someone at that distance, but will sure slow them down some. Its nice to know this pdw i have with me driving around here in south tx is capable of touching someone out to that distance.