Dedicated AR upper for shooting cast boolits

[btreanor]

Hey folks- I'd like to assemble an AR upper and dedicate it to shooting cast boolits. Specifically, I'd like to install a 20 to 24" barrel with a 1 in 12" twist and have a larger gas port installed (maybe like the ones used in AR pistols) to ensure functioning with lower velocity lead boolit rounds. I've assembled and substituted a lot of components in AR lowers and my gunsmithing skills are pretty good (but not on a professional level). However, I've never attempted to assemble an upper. Specifically, I was wondering if anyone has any experience or resources they could share in the following areas:

1. Where I can find good instructions for building/assembling uppers with custom barrels
2. Good source(s) for custom built AR barrels (1 in 12" twist with larger gas port for cycling lower pressure rounds)
3. Good source(s) for the other parts needed to assemble an upper
4. Any other advice for best possible accuracy (like free-floating the barrel, etc.) would be most welcome!

Many thanks,

Bill

[Texas by God]

You might check with Green Mountain. Along the lines of what you want, I'd like a 12" twist .300BO barrel for cast use.

Sent from my SM-A716U using Tapatalk

[Finster101]

There are a lot of videos on assembly. Midway actually has a pretty good video library. You will need a mount to put the upper in a vice to avoid racking it when torqueing the barrel nut. If you have the tools and follow directions it should not be too difficult.

[Hitnmiss]

How heavy of a boolit are you looking at shooting. 20 inch barrel is long for 223/5.56. My 18 inch with 1:8 likes 70 plus grain boolits. My 16 inch 1:7 loves the heavy ones as well. Both are carbine length gas systems. Both have adjustable gas blocks as well.

Please spend some time looking before spending money.

[Lloyd Smale]

hard to beat a 300bo for cast bullet ars. No need to loose sleep. buy a psa 300 bo upper in the length you want. Ive got them from 7 inch to 18 in and they all run perfectly.

[Iron369]

You didn’t mention desired caliber.

[1006]

You might consider one of the 9mm carbines. They are usually blow back operated.

The down side is you will breath a lot more fumes while shooting long strings of fire. The upside is that they are very reliable, shoot lead boolits well, are fairly accurate out to 100yards, and cheap to shoot when ammo is available.

[Lloyd Smale]

You might consider one of the 9mm carbines. They are usually blow back operated.

The down side is you will breath a lot more fumes while shooting long strings of fire. The upside is that they are very reliable, shoot lead boolits well, are fairly accurate out to 100yards, and cheap to shoot when ammo is available.

excellent advice. Much cheaper to shoot and a heck of alot of fun. Big advantage to in a shtf senerio is you can use the same mags your carrying for your glock.

[dverna]

Question on blow back 9mm's in the AR. I had a Sub2000 and sold it as my lady found it difficult to rack the action. How much effort does it take to rack the 9mm AR's?

[Iron369]

Question on blow back 9mm's in the AR. I had a Sub2000 and sold it as my lady found it difficult to rack the action. How much effort does it take to rack the 9mm AR's?

Just like any ar15.

[farmbif]

Uppers are much easier to assemble than lowers. most difficult parts are getting the springs right in ejection port and shimming and torquing barrel nut so that front part of rail lines up with the upper casting rail. Its all very simple and if you have just a couple of the basic tools like a good AR wrench and good punches its actually quite easy. I used to help out at a real gunsmith shop and dont consider putting together an AR gun smithing and I sure aint no gunsmith.
The few AR's I put together I did just sitting at a big desk top.
even the super inexpensive guntec hand guards that mid south sells come with a wrench to fit barrel nut.
there are probably 1000's of options as to where to get parts and different brands.
do yourself a favor and get a nickel boron coated BCG and stainless gas tube
as far as barrel ports that's way above my pay grade

[popper]

I have a 18" 1:10 BO barreled upper that shoots cast fine. Longer barrel gives no advantage. Powders for BO burnout is past muzzle but little increase in fps. OP didn't say what cartridge he wants to shoot, makes a difference. Get the clamshell upper holder and use a wrench for the barrel. Most hand guards don't use the old mil type nut anymore and it normally comes with the hand guard. Gas block and tube are all standard. Easy peasy stuff.
I shoot 308 and BO cast in my ARs, no problem. I don't run them slow, no reason to do that. Xcaliber barrels.

[btreanor]

Sorry I wasn't clear- I'm looking to shoot .223 cast, specifically the Lee 55 gr. GC boolit. I already have a .300 BO upper. Thanks!

[popper]

Read up from the guys that have tried it before you commit.

[Ickisrulz]

Question on blow back 9mm's in the AR. I had a Sub2000 and sold it as my lady found it difficult to rack the action. How much effort does it take to rack the 9mm AR's?

Pretty much the same as an AR15 in 223.

[Lloyd Smale]

Sorry I wasn't clear- I'm looking to shoot .223 cast, specifically the Lee 55 gr. GC boolit. I already have a .300 BO upper. Thanks!

you picked about the hardest platform for using cast. I played with it for a whole summer and found some mediocure results. Im talking 3 inch 50 yard groups. I have loads that come close to moa with cast in my 300 bo and believe it or not the same out of the 9 and im talking a 100 yards. My only cast 556 anymore is a coffee can full of pc coated 55 grain gas checks i keep for if shtf and i had to have SOMETHING to make my gun go bang.