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AR15 Pistol Questions

shastadude17

Regular Member
Joined
Dec 13, 2011
Messages
150
Location
United States
I suppose this is technically the proper place for this thread =P

This weekend I got the ball rolling on my AR15 pistol project by purchasing a Tactical Weapons Solutions AR15 pistol lower. Now the tricky part is finding a suitable upper. My budget is around 600 bucks, plus or minus. I've been looking for a while now, and I'm dead set on a 10.5" barrel with a lightweight quad rail, flat top, and a rail on the gas block so I can mount a flip up front sight.

Wanted to know if I should roll 1:9 twist or 1:7 twist, I plan on mainly shooting 55 grain and 62 grain, not really concerned about going up to 77 or anything crazy.

Also wanted to know if anyone had experience with the Fail Zero bolt carrier groups, and if it is necessary to have a gunsmith headspace them or if you can just drop them in.

Not looking for any super operator neckbeard tacticool high speed flash suppressors or gadgets, a simple A2 flash hider and charging handle will do fine. If I have to buy a bolt carrier group and charging handle separately, or even the rails, I'm fine with that. Just not really sure which upper to buy! Thx guys.
 

MAC702

Campaign Veteran
Joined
Jul 31, 2011
Messages
6,331
Location
Nevada
I routinely shoot 69- and 70-grain bullets with my 1:9 twist. I believe that is the better choice for 55-grain as well.
 

shastadude17

Regular Member
Joined
Dec 13, 2011
Messages
150
Location
United States
What length on your barrel Mac? And they have some cool 7.5 inchers at RedX for sure. Right after I posted this I found the RRA uppers and LMT uppers and I think I'm leaning towards those even though they have fixed front sights, not really sure what kind of rail system to get though. Anyone have any experience with different quad rails?
 

jeeper1

Regular Member
Joined
Sep 29, 2008
Messages
692
Location
USA
Go with the 1 in 9 twist. The 1 in 7 twist was designed for the 62 grain and heavier bullets.
 

MSG Laigaie

Campaign Veteran
Joined
Jan 10, 2011
Messages
3,239
Location
Philipsburg, Montana
I recently completed an AR15 pistol. Took about twenty minute to assemble from a kit. Paid US$530 for the kit, including all parts but the stripped lower. As you see, 10.5 barrel in 5.56 with railed gas block and extended latch. Piece of cake to assemble and it shoots like a dream. M1 Sales
 

Jayd1981

Regular Member
Joined
Mar 14, 2010
Messages
387
Location
Richland, Washington, USA
I built an AR-15 pistol last year. Purchased my upper from model1sales. They are a fun toy. One thing I learned is that the gas system wasn't designed for such a short barrel and it had a tendency to not be able to extract the round after firing. I had to use a heavy duty extractor spring to be able to overcome that. I would not worry about headspacing the bolt, just use a new bolt with a new barrel.
 

REALteach4u

Regular Member
Joined
Nov 25, 2010
Messages
428
Location
Spfld, Mo.
I'm not big on the AR pistols, so I have an odd-duck of a question to go with the OP.

Given that it will be a short barrel, how much will that impact the twist ratios for those shorter barrels?

I'm wondering if the shorter barrel makes it a moot point (say on the length of the Rock River PDS) as is the case with snub nosed revolvers in the world of +P where because of the shorter barrel length you do not obtain enough of a powder burn, thus making the twist almost a dead issue. Would the AR pistol fall within this same type of issue?

I know some companies have added extra grooves to compensate for shorter barrels. Thoughts?

Here's the PDS by the way and I would love to have one, but I have no true purpose other than it being a $1000 toy.
http://www.tactical-life.com/online/combat-handguns/rock-river-arms-pds-556mm-2/
 

Jayd1981

Regular Member
Joined
Mar 14, 2010
Messages
387
Location
Richland, Washington, USA
As far as I understand, the bullet will spin at the same rate regardless if the barrel is 10" or 20". But the powder will still be burning when the bullet leaves the barrel with the shorter barrel, that will effect the velocity of the barrel. For example an AR with a 20" barrel will give 200fps more than an AR with a 16" barrel. However you can get a cool fireball with shorter barrels, such as Mosin Nagant carbines. Those create quite the fireball.
 
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