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I am thinking of building an 6" to 8" pistol length .45 acp barreled upper for my sbr lower.
I also have an 45 Osprey suppressor that I want to use more often.
Any pitfalls that I need to be aware of, like which mags work the best, top or bottom drop in magwell conversion, slick side upper, etc.
Any advice would be appreciated.
 
Thanks for the leads.
There seems to be more problems then solutions with .45 acp conversions, so I'm going to look at 9mm as an alternative.
 
Seems that you need a dedicated lower to run the .45 in a AR. Kind of not worth it if you are looking to use it on a SBR lower.... Or just drop another 200 on a tax stamp:)
 
Just a tip for searching, use google and the following syntax in the search bar. The search will return any combination of the search terms.
search terms site:urlofsite.com

Example:
45acp upper site:ar15.com

If you need a specific phrase put it in quotes. It will not search for any combination of terms, only that permutation. You can also mix and match quotes with no quotes.

Example:
"has anyone built an .45 acp" Olympic upper site:northwestfirearms.com
 
I've read about this subject on the web till my eyes dried out.
What I want is someone on this site that has actually built one and how did it perform after the build.
AR15.com is the most convoluted site to navigate through, so a first hand experience is what I'm after.
 
Good question. The FA Tommy has never been fired single shot and as much fun as full auto is, it's expensive to operate.
So I thought that since I have an sbr lower, why not build a .45 short barreled upper that I can hang my .45 Osprey on and have a cool looking and quiet AR that hopefully would accept Thompson stick mags that I have a bunch of already.
The Mac 11 is also full auto and it came with a Bowers suppressor, but it's a total spray & pray machine that is even more wasteful of ammo, plus it doesn't have the heft and feel like the Tommy.
 
Here's my thoughts, Jbett.
If it's not a handgun, then it's a waste of a 45 if it's not a Tommy Gun. (my Holy Grail, if you must know) If I'm shooting something in a carbine form, I want some kind of rifle, or short rifle, cartridge. Heck, even the 7.62x39 whomps the 45 in power. If I gotta use two hands, I want the capability of some distance.
My choice, not yours.
If I was looking at a pistol caliber carbine, I would pick the 45 ACP just because I have ammo!
 
I have an integrally suppressed 9mm "Glock" AR so it is 16" barrel with the can attached. It is a ton of fun.

I got to shoot one set up basically the same way in .45 and it was awesome. I don't recall what lower he used, but IIRC it took Grease Gun mag. I wanted to build one like it for a long time, but an expensive project for something that I would hardly shoot.

If you google ".45 AR lower" there are tons of hits, with a few options.
 
The Mac 11 is also full auto and it came with a Bowers suppressor, but it's a total spray & pray machine that is even more wasteful of ammo, plus it doesn't have the heft and feel like the Tommy.
Are you shooting your M11 with the factory upper or do you have a Lage upper for it? The Lage uppers make a huge difference in enjoyablity of the M11. If you want to try mine, I'd be open to meeting up for some shooting.
 
I thought about buying a Lage upper a year ago, but they quit making them, so the price of used ones have more then doubled.
I would like to try one out before I plunk down over $900.00.
I could bring the Tommy along if you want to rattle a couple of 50 rd drums through it.
 

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