Ask and ye shall receive
Here, I said:
Think I’d rather have one [an AR-15 – ed.] in 45 ACP.
Well, via reader bob, CNC gunsmithing to the rescue with the AR45:
It’s time for something a little bit different. The same guy who shared with me his idea of the A1 detachable carry handle, William Putnam, also dreamed up another idea. He wanted to use M3A1 “grease gun” magazines (which are .45 caliber) in an AR15 with a .45 cal. upper receiver. Olympic Arms sells .45 cal. upper receivers but they come with a modified Uzi mag with a built-in mag well block. The mag is single stack, so it’s not real high capacity mag. William was wanting to use the grease gun mag so you could have more trigger time between reloads. The problem with using grease gun mags is that the body of the mag is about the same width as the outside of a normal AR15 mag well. So you can’t simply modify the AR15 receiver and expect it to work. In order to get this to work, a brand new receiver would have to be machined from a billet of material to allow for a wider mag well. One company has attempted this idea, but they used plastic receivers which aren’t very versatile, as you can’t change out the stock and pistol grip to fit your needs. They also used a mag catch similar to that of the AK-47. With that method, you have to hold the rifle with one hand, and then with the other hand grab and release the mag, then reach for another mag and insert it in the receiver. I wanted to stick with a normal AR15 look and feel. I wanted to be able to drop the mag by pushing the mag release button with same hand I am holding the rifle with while at the same time reaching for another mag. This method would be alot faster than the AK47 style of mag release. I also didn’t want to move the location of the mag release button, since AR15 users are already familiar with it’s current location. So I started to work on the solidmodel design of the receiver and I came up with something I thought would work. I’m going to call this new design the AR45. It will be using an Olympic Arms .45 cal upper receiver. In the pic above you can see how the mag well is wider than that of an AR15 receiver. I’m not going to give a whole lot of details about how it’s going to work just yet, but I’m 99% sure it will work. I have already made a test piece and it worked perfectly. As I get closer to finishing the receiver, you’ll see exactly how this design is going to work.
Nice.
August 8th, 2006 at 2:21 pm
Interesting, but with a 9-round magazine, it may turn out to be an answer to a question no one asked.
Hypothesizing…..if it fits a standard AR mag, the cartridge OAL has to be less than about 45mm. ’06 brass is close enough to work, but 9.3mm brass is closer to what seem like the right diameter specs for an unbelted round for a .451″ projectile. Max projectile exposure on a 45 ACP round is .3770″ (9.58mm), so that leaves 35mm maximum for the case, figure a little shorter, maybe 30-32mm, which is 1.18″ – 1.26″. The 45 Winchester Magnum case is 1.198″ long, almost in the middle. My Speer manual has a few 45 WM loads that are about 2X max velocity of 45ACP (1650 FPS – 230 FMJ), so there’s some ballistic promise there. That puts it in the hot centerfire pistol cartridge range, and offers competition to the 44 Magnum; the 458 SOCOM is almost a 444 Marlin or hot .45-70 in power, which may be too much for a pistol-caliber carbine. A .451″, 230gr HP at about 1250-1400 in an AR-style package with straight line recoil could be attractive.
I don’t see anything about the 45 WM case that would justify creating a new, and proprietary, case to almost duplicate it, but I don’t shoot/reload it, so maybe someone more familiar with it can shed some light on it. It might be a magazine/feeding issue for the AR mag.
A staggered 15-round mag might have some promise, as might a different cartridge. Some years back there were extended versions of the 41 and 44 magnums, the only remnant of which seems to be the 357 Maximum.
Were the same treatment to be performed on the 10mm auto case, it would gain about .200″ and maybe about 15% in velocity, producing 1400+ FPS for a 200 grain .400″ projectile. And, a higher magazine capacity, which would be negated by a staggered 45WM or 45 Bushmaster magazine.
Be interesting to see where this goes.
August 8th, 2006 at 5:49 pm
Cavalry Arms already makes a polymer lower that takes grease gun mags and it is cheap. The lower plus the hahn precision adaptor and buffer together cost maybe 300 bucks.
The AR45 thing has been in the works a long time with nothing going to production yet. I just finished building my Oly arms upper + cav arms lower + grease gun mags this week and next week it goes off to SRT for a suppressor I’m hoping.
August 8th, 2006 at 5:51 pm
Avoid the mil-spec lowers if you are trying to build a 45 acp AR. The uzi mags are the only ones that fit and they are supremely rare and expensive.
Anyone who had an order for a complete AR45 is going to be held up for a while because Olympic cant find any magazines to use. Oly makes the industry standard for 45 acp uppers, but not going with a grease gun mag lower is foolish.
August 9th, 2006 at 12:17 am
Somebody out there makes a “modular” AR15 lower, comprising a magwell front module and the rest in a rear module. They fit together with a vertical dovetail.
It was made for the purpose of offering an AK magwell for 7.62×39 users.
A different front magwell module for the M3 would be no harder. In fact, the manufacturer plans a Grease Gun magwell. Are you patient?
I’d be content with a 10mm Dornaus&Dixon chambering. M1 Carbine mags might work, which may fit into the existing AR magwell anyway.