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.45 ACP Conversion Guide
TANGOCHASER  [Team Member]
Interest in .45 ACP conversions has grown by leaps and bounds in the last year due to a number of new options available to builders. Here is a base of information as I know it. Please feel free to correct any bad info and add any info not mentioned.

Olympic Arms is the only manufacturer of a factory built .45 ACP conversion. Their upper receiver is designed to use a standard AR15 lower receiver with modified Uzi .45 ACP magazines. Oly ran out of Uzi mags and there is no current .45 ACP mag that will work with a standard AR15 lower. Oly is planning on releasing a new .45 mag that does fit in a standard AR lower receiver in December 2007.

The Oly .45 upper receiver is a blowback design with the weight of the bolt carrier holding the round in battery when fired. The ejector system in a spring set up mounted in the upper receiver. Any AR15 upper receiver can be used but 3 small holes for the ejector need to be drilled and the ejector installed.

This is the Oly ejector set up installed in a regular AR15 upper receiver.

Here is the print for the holes for the Oly ejector installation. The .125 hole is drilled on the opposite side as well.

The AR45 lower receiver is a three way enterprise between Tango Chaser Tactical, CNCGuns, and Khalan Weaponry. It is a billet lower receiver designed to use unmodified grease gun magazines. The magazine release is in the standard AR15 location and uses standard AR15 lower parts except for the magazine catch assembly. Around 100 have been made and sold to date. Future plans call for a forged lower to reduce cost and a complete AR45 carbine will be available spring 2009.

Bazooka Bros .45 lower receiver is designed to use grease gun magazines and use an Oly .45 upper. The lower receiver is a two piece receiver mating a grease gun magwell to the back half of a standard AR15 lower receiver. Early versions required a new magazine catch slot to be cut into the magazines. The BAZ45 has been on the market for some time and is reported to be very reliable.

Cavalry Arms makes their MKII polymer lower receiver that is widened in the middle of the magwell to accommodate the use of a grease gun mag to work with the Olympic Arms upper. A Hahn magwell filler block is required to hold the grease gun mag in the magwell and uses a lever type mag release. The Cav Arms lower also requires a very heavy buffer like the Slash buffer to prevent damage to the lower receiver from firing the .45 ACP round. The primary drawback to the Cav Arms lower is it's one-piece design. Users can not change the buttstock or the pistol grip.

This shows the Hahn magwell block installed.

LaFrance made a AR15 type carbine that used Thompson SMG magazines. It has been reported that LaFrance sold only to law enforcement and military is no longer in business.

MGI is reported to have a removeable magwell that uses grease gun mags for their CQB weapon system but no release date has been given.

Grease gun mags vs Thompson mags. Grease gun mags are the easiest to use for .45 ACP conversions as no other mods are needed to the Oly upper receivers. Thompson mags require the clearance cuts to the bottom of the bolt carrier and inside the bottom of the upper receiver to clear the magazine. Mag catch slots also need to be cut into the magazines to work with any of the lower receiver systems on the market.

Some arfcomers have machined a standard AR45 lower to accept the Thompson mags with a magwell block but the additional modifications to the upper receiver were still needed.

Grease gun mags are too wide to fit into a standard AR15 lower without extensive modifications to the magazines. Dalphon used to sell such modified mags but is no longer in business.
I don't have a website for Bazooka Bros.

Moderators, please tack this thread as these questions get asked about 2-3 times a week. The .45 conversion will become much more popular as shooter attain knowlwdge as to how to build a .45 set up.
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TANGOCHASER  [Team Member]
Here are two more spin offs. First is a .45 GAP upper receiver I made last year using a Thompson SMG barrel. I had a local machinist take a few thousandths off the chamber end till the chamber was the correct depth for the .45 GAP round and the cut new threads to match an Oly barrel extension.

Fire from a Sten mag like a raped ape.

Here is a prototype of a lower that uses WWII Reising SMG magazines. Concept works and I am having a dedicated lower made from a forging for Reising mags. Only real issue is the cost of mags. About $60-$80 a piece. Factory mags are 20 rounds but a guy named Ken Christie made a limited run of 30rd stainless steel mags.

Here is a live fire video. Don't pay any attention to the buttstock falling off after the test fire. The threads in the lower were stripped and my repair failed.
Brotherhood-of-Steel  [Member]
Outstanding! I am looking into gettng a .45ACP m4 type carbine. This post helps alot
MMcfpd  [Life Member]
Thanks for resurrecting this, TANGOCHASER.

Magazines - what to use and how to make them usable - seem to have always been the problem with these, and other pistol caliber, conversions for the AR.

As noted, the alternatives include primarily Grease Gun magazines and also Uzi mags. Oly may have a polymer magazine out sometime in the next year, and Thompson mags have been worked with by some. While typing this I see that TANGO has worked with a Sten mag and a Reising mag also. One aspect of using GG mags or Uzis that may not immediately come to mind is that they are (really) long compared to regular AR mags: Here are a standard USGI 30 round 5.56 mag next to a 16 round Uzi mag (with an Oly mag block welded on) and a 30 round Grease Gun mag:

The Uzi mag option would seem to be the easiest route to pursue, as it requires only a standard lower, but it's not. Besides being limited to 16 rounds (if your thumbs are up to the loading), Uzi mags are just plain hard to come by and rather pricey. It took about two months of haunting Gunbroker to scare up six 16 round Uzi mags earlier this year and during that time I saw them go for up to $305(!). Then I sent a batch off to Oly in May to be modified (another $35/ea.) and got them back last week (October).

But don't let me discourage you. The .45 AR is a hoot to shoot, and you'll be rewarded if you carry on through a conversion. I think TANGOCHASER is correct in saying that this will likely become a more popular conversion as more people are exposed to it. And I think he's probably the granddaddy of this conversion.
TANGOCHASER  [Team Member]
.45 ACP Hollow points can be fired from Sten mags in a pinch. FMJ are too long without modifying the mag. Just needs a Sten magwell block and open up the feed lips a little.

And that's my wonderfull wife taking some brass for the home team in the video.

PS. Those are not double feeds, they are bump fires. Trigger is really light on that lower.
Hawgleg44  [Member]
Hmmmmm......... .45GAP using STEN mags, huh? great idea. If I didn't get one of the first CNC/Khalan AR45's and now having 17 GG mags, I'd have you set up an upper to go that route.

I really like that idea!
TaylorWSO  [Life Member]

Originally Posted By TANGOCHASER:
.45 ACP Hollow points can be fired from Sten mags in a pinch. FMJ are too long without modifying the mag. Just needs a Sten magwell block and open up the feed lips a little.

And that's my wonderfull wife taking some brass for the home team in the video.

PS. Those are not double feeds, they are bump fires. Trigger is really light on that lower.

HS that video was funny

"you're going to screw up my recording"

"What did you think it was going to do"

seems like a good time for a pic

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nugentgl  [Team Member]
MODS - PLEASE STICKY THIS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
hwydrifter  [Member]
I got an 45 cal. olympic I bought new back in 95 with 3 factory 10rnd mags, I love it. very accurate, never jams, very little recoil.
looks like I need to hang on to it didn't know they were hard to get now.

MMcfpd  [Life Member]
hwydrifter, just curious, you have an apparent carbine (16") barrel with an A2 stock - what buffer and recoil spring are you using?
Hawgleg44  [Member]

Originally Posted By MMcfpd:
hwydrifter, just curious, you have an apparent carbine (16") barrel with an A2 stock - what buffer and recoil spring are you using?

With my Oly .45, I use just the standard .223 spring and buffer. I've never had any problems at all.

I started out with the three converted 10 round Uzi mags that I got with the used upper. But now, since I have my CNC/Khalan AR45 lower, I'm planning to put all three of them up on the EE. I have 17 NIW (until I used them, that is) GG mags and I don't see myself ever inserting another .45 Uzi mag into a magwell again.
hwydrifter  [Member]
what Hawgleg44 said. I have a standard 223 spring and buffer. I bought it the way you see it. brand new never changed a thing on it.
wildearp  [Team Member]
I ran my .45 Oly a RRA M-4 stock, spring, and .223 buffer with zero problems.

I ran full length 230fmj in modified stens. I will put up photos of the mods if I can find them.
October_V  [Member]

I wish this would get pinned!
TRWalsh  [Member]
AR45 upper currently under construction. Space reserved for future pics.
TANGOCHASER  [Team Member]
BTT Requesting a tack from a moderator.
cnatra  [Team Member]

Bigred200e  [Member]

Originally Posted By TANGOCHASER:
BTT Requesting a tack from a moderator.

+eleventy million
GP40X  [Team Member]
Well that was a bust. I tried to join the CNC Gunsmithing forum to see of there was any more current information on the AR45 lowers and their forum software will not send me the confirmation email. I have made several requests and it always says it will send it shortly. Hours later is NOT shortly!. Anyone have any current information on the 80% lowers or if they are going into production on complete lowers anytime soon? How about the availability of the Oly parts? I really want to build one of these.

Another +1 for a sticky
bushwack  [Member]
Justin at CNC & Mitchell at Khalan are working on making the lowers a stocked off the shelf item. As it is now, you buy a 10% lower from CNC & he can send it to Khalan who will finish it in just about any configuration you want. Then he ships it to your FFL. This is just getting started & it's pretty much a two man operation, now that TC has taken a new job. They are getting barrel makers lined up to furnish 45cal barrels & will offer uppers, or so the plan goes. They just didn't know the AR45 was going to take off like it has. The market is there.

+1 on the tacked thread
TRWalsh  [Member]
Send Justin an email. He'll get back to you.
Hawgleg44  [Member]
I just had my AR45 from the beginning of the first batch out again today. I love that thing. It ate a steady diet of 200gr cast (wheelweight alloy) SWC with a charge of 5.1gr of 700X. I'm still working a few bugs out of the upper, though. I occasionally get the spent round failing to eject and getting jammed by the bolt into the face of the barrel, above the chamber. I don't know if it's a weak ejector spring or what. I can't see how that's possible since the upper is almost new, but I guess it could be a bad spring right from Oly. It happens 2-3 times every session of 200-400 rounds.

Any ideas Tango?
TANGOCHASER  [Team Member]
Might be the extracor needs to be cut a little deeper or opened up a little to grab the rim better. I believe part of the problem is the way Oly sandwhiches the extractor spring between the extractor and the carrier instead of the traditional AR15 method of putting the spring between the extractor and the bolt.

The spring is almost bottomed out on normal installation and I wonder if that isn't part of the problem.

Then again, it might just need that 200-500rd break in period before it stops acting weird.
Hawgleg44  [Member]
It's seen about 1000 rounds since I bought it, and the previous owner said he shot it only 200 rounds. I'll start fitting the extractor tonight.

TREETOP  [Site Staff]
TaylorWSO  [Life Member]
Thanks for the tack

GG mags

tac inc 37 bux
IMA 25 bux
keep shooting new production 20 bux
Jo R lower 35 bux
bowers 35 buck
numrich 30 bux
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