Looking to build a new SBR in eather 9mm or .45ACP. Not real sure on what exactly was avalable in 9mm as far as barrels and uppers, but for .45 i was going to go with a Ron WIlliams build. The main use of this would be Subsonic plinking, with possbily some critter control, which eather round would be capable of handling.

Price of ammo is 13.99 a box of 9mm vs about 19 for .45. What would be my best choice, and would eather be quiter than the other if both are subsonic? Which would you choose, considering mags and such possibling being a PITA.

Unless you are/plan to reload, the 9mm will be cheaper. Either one will be bad ass suppressed. If I knew I could get one and it run right, I'd go big with the .45.

9's are more common and you'll have more options. I've heard that 9's suppress better too. I had thought .45's would, but it's the 9's smaller bore diameter letting less gas out all at once. Been told this by people with experience in the matter.

.45 SBR makes me think of Thompsons. :)

.45 lovers love .45, period. They have a case. But, for many of us 9mm makes a lot of sense, as in dollars and cents. Far easier to build (more parts choices), cheaper to shoot and much easier to find magazines, etc. The argument that .45 is the only round worth shooting, for me, ranks up there with a Harley being the only motorcycle...the rest are toys.If I wanted a range toy and some light work I would go with 9mm as its far less hassle and expense. If you really have to have a .45 then get out your credit card and give Ron Williams a call.

RMW can do a 9mm too..... As far as 9mm vs 45, it makes the world go round....

Dave S

So, your plan is to shoot cast bullets in your sealed Osprey 45?

Lube and lead flung all around? No thanks.

I have a 16" 9mm carbine &
a 7" 9mm pistol, both Oly's.
They both use slightly modified
Sten mags. Those mags are
built like tanks, and are pretty
cheap.

One or both go with me every
range trip and match.

John

Kinda like indirect fire...........

If the .45 is DI......it'll have less recoil than any blowback AR.........I have both.......have the blowback primarily to demo prior to showing a DI

If you choose to go with a 45 ACP setup you can add a 45 supressor, then as time goes by get yourself a 9mm setup and use the 45 supressor on it also

After a lifetime of shooting cast boolits (cast by me in some cases), I've been drifting away toward jackets due to high blood lead levels. A lot of my shooting is at an indoor range, and despite major ventilation improvements, I'll likely continue to shoot more jackets. I shoot outdoors as well, and roll my own ammo, but at some point it stops being effective to load and stockpile two different loadings depending on where you're going to shoot it.
Which takes us (or at least me) back to 9mm as a more cost-effective way to shoot, as the jacketed projectiles are just a whole lot less expensive in material and (a biggie) shipping.

One of the many great things about a pistol caliber carbine is the ability to shoot it indoors without damaging backstops, and at reactive targets as well. I'm still laughing about the PP shooting at 400 yds with one; wonder if he ever calculated how high above line of sight the round goes before coming down on the gong? That's just a hoot!

Utterly no bone to pick with .45s; the 1911 is one of mankind's great inventions. But for shooting, and lots of it, in an AR carbine, the smaller round is the way to go.

What I will be picking are some brains around here regarding suppressing an SBR at some point.

Moon

I don't post much here and normally just read & learn but I have to ask... How is 9mm easier to suppress? If you're goal is to have something that is easy to shoot quietly wouldn't a platform where almost all loads are subsonic be the best? You can go to walmart and buy 230 gr bulk .45 that is much easier to suppress than regular 9mm loads, off the shelf sub sonic 9mm that may not cycle, expensive 147gr loads that negate the cost savings of 9mm, or starting to load your own 9mm just to achieve subsonic suppression.

I'm looking into a .45acp SBR for a suppressor host so I thought I'd ask.

I have not heard a suppressed .45 carbine, but I have shot suppressed .45acp pistols.
They are quiet enough for me with 235 grain projectiles. Without hearing protection, I could
hear the action cycle, a little phht noise, and the loudest sound was the bullet striking the berm
25yds downrange.

If you want to shoot suppressed, .45 is the way to go.
You can get heavy bullets that are designed to have good terminal performance at subsonic speeds.
For critter control, a heavy .45 sub will get the job done and it will work with factory loads.

For 9mm, you will struggle to find a load that will stay subsonic. You will have to buy specialty subsonic
ammunition with 147gr or greater bullet weight. If you can find the ammo in stock, it will cost you
$20 - $25 per box.