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.

www.cncguns.com/
khalan.com/
www.olyarms.com/
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.

Looks good! How about some 9mm stuff? Will that be on the new website?

...

Hey Rudy, I've been running my setup for about two years now....no issues...thank you.  Getting into the full auto and should have my RR in a few months.  How much are your new mags and the mag well adapter?

I'm using pop up flare molle pouches for my GG mags. They work fine mounted on a short molle leg panel. Just keep in mind a loaded GG mag weighs 2lbs..

I recently received an AR45 lower from CNCGuns and not even one of my 20+ USGI surplus grease gun mags will even start to fit in the mag well due to it being about 5-10 thousandths short front to back.  I did squeeze one magazine progressively in a vise until it fit mostly drop free, but I am not too thrilled about doing that to the rest of my mags and also (possibly due to the squeezing) I can over-insert the magazine if I push up too hard. Not good.  Maybe a stronger spring will fix this.  Fortunately it locks up good enough to prevent it from getting pulled out without the mag release button pushed.

Anyhow, I noticed that as I was getting the one magazine to fit, it appeared as though it was the rear mag well corners that were contacting.  The radius of curvature for both the mag well and the rear of the magazines both seem to be pretty close to 1/8" radius.  Is it just an optical illusion or diffraction that makes it appear that the corners of the mag are the culprit? I don't know.  It  looks like from these previous posts that a 1/8" radius is what should be there (i.e., 1/4" diameter end mill) and is what I have, but has anybody had any luck on these newer 'proper' lowers in using a smaller radius end mill or small round burr to square up the back of the mag well to get magazines to fit without squeezing them in a vise?

Personally, I would rather have an ugly looking scarred up mag well then squeeze all of my mags in a vise...I won't even comment on that apparently intentional design.

Thanks,
Esox

Are you using USGI mags or Keep Shooting brand mags? The Keep Shooting mags have always been tight. The USGI mags were made by multiple manufacturers and varying tolerance, hence the squeeze technique.

I do not own any KS magazines.  I have a mixture of mostly blued and some parkerized magazines that are orignal GI issue.  Most of them I personally unwrapped from 1960's date coded wrappers.

My mag well dimensions are 1.550" front to back and 1.095" side to side, whereas my magazines average 1.560" +/- 0.005" front to back and 1.080" +/- 0.005 side to side.

Based on a variety of links, the front to back dimensions of a 'standard' USGI grease gun magazine should be 1.550 - 1.5625" long.  I estimate that there needs to be about 0.005" (maybe more?) additional room in the well for ease of insertion and drop free characteristics.
http://www.uzitalk.com/forums/showthread.php?24726-Dimensions-of-an-M3-grease-gun-mag
http://www.weaponeer.net/forum/forum_posts.asp?TID=20580
http://www.homegunsmith.com/archive/T11876.html

Get ahold of Justin @ cncguns. He'll make it right.

I did. This lower is within spec based on his blueprints.  Let me say that Justin makes a great lower to his spec and the finish on it is spectacular...and to be fair, the CNCGuns website clearly states:

"NOTE:  The AR45 uses unmodified grease gun magazines and a standard AR15 lower parts kit.  Grease gun magazines are manufactured with pretty sloppy tolerances so you may find some mags that fit the AR45 mag well just fine and then you might find some that are a little snug or won't fit at all.  If this is the case then it's an easy fix.... just determine if it's the width or the length that needs to be tweaked and then just simply squeeze the magazine very lightly in a vice.  I've purchased magazines from several different sources and I've never ran across a grease gun magazine that wouldn't work in the AR45."

Caveat Emptor.  I guess I am just 'unlucky' in that none of my 20+ magazines fit.  I choose to not squeeze them all in a vise since I use them in two other guns and I assume all risk of bungling up the receiver.

I guess that leaves filing on the magwell to fit the mags.

Well, I guess I will plan to use a long reach 1/8" end mill to very slowly remove material from the back of the well and cut a smaller radius in the rear corners at the same time.  If anybody has done this before, what was the final front to back length that worked out well to balance ease of insertion with drop free mag capability?

Thanks Rudy!  I think my primary issue is the front to back depth and to a lesser (or maybe equal) extent the rear radius. I obviously want to remove as little material as possible off the rear wall to ensure that the mags don't wobble after being inserted.  These mags do have some manufacturing variability, but it is really not all that bad based on my measurements of my magazines.  In fact, I am okay with needing to square up any mags that I have that present obvious contact points.  I am not okay with needing to squash all of my magazines just to get them to fit. I will enlarge the mag well enough so that most of mine will fit and I will do the minor tweaks required to the remaining 'outlier' magazines.

Now to the potential radius issue...when I squashed one mag progressively to get it to fit and just drop free I noticed that when looking down the mag well to check for contact points that it appeared to be binding up on the center of the rear radius.  I checked both the mag and the well with a radius gauge set and they appear to be very close to a 1/8" radius...so they shouldn't bind up there.  Sometimes views like that can get distorted due to shadowing effects and what not, but on the other hand it only takes a very small change in a radius to create a contact point and bind things up.  So, I am going to go with the assumption that if I tighten the radius up it can't hurt and it will potentially allow me to remove less material off the rear wall.

Yes, I could plunge with a larger diameter end mill, but I think I know where to borrow a 1/8"  1 1/2" cut end mill to keep it looking a little more OEM.  Of course, this would require that I make cuts from both the top and the bottom to clearance the entire depth of the well.

...and next in line on this project is to order a DI upper from you!

Interest will peak more if they had glock mag compatibility for the AR-type lowers. Kinda like the 9mm by NewFrontierArmory or PSA.

Here it is!  Stamp (efiled 12 May) just came in yesterday:



I was lucky to find new-in-wrapper USGI greasegun mags.  I have 4 and all fit very well and drop free.  I hope to get out and shoot it today.  It has a Larue MBT inside.

Those are blued instead of parkerized, right?  If they are blued they are not USGI.
Probably from KeepShooting, they have them for $30.

The USGI mags are grey parkerized, and are noticeably thicker/heavier.  I've had no trouble with either, after some minor feed lip adjustments to some, and a little squeezing on the GI mags.

They are blued.  I understood the 'keep shooting' versions were painted and that was throwing them out of tolerance.

These came in foil USGI wrappers and appear to be un-tampered with.  I will check for markings tonight.

You may have actual USGI mags then, every one I've seen in person has been grey parkerized.
The KS mags are blued, and are noticeably lighter than the GI mags i've got.  The KS mags also fit into some guns that won't take unmodified GI mags easily.

Here's my .45 before I SBR'd it and redesigned the action.
KS mag on the floor, shortened GI mag in the gun.

There are blued USGI mags. There were multiple suppliers of these mags during WWII. I have a few that I acquired before Keep Shooting even existed. The USGI mags also have two different versions. The mag catch slot on one style is shaped like a "D" and the other is squared.

Stamped on the front:  SPW  GL  C-153427 on all 4.  I bought three from a reputable source who sold out his whole inventory and it made his head spin a bit.  The fourth was from armslist with exact same markings.  D shaped whatchmacallit....



GL = Guide Lamp


So, UUUUUGE issues with my new carbine.


1.  Couldn't keep mags full

2.  ran out of ammo very quickly

3.  caused severe damage to target, uuuuuge hole in it

4. four mags is no where near enough.








This thing is sweet!!!  I had to adjust one mag a bit more (feed lips), but I think I have it right now.  I haven't been whole since I sold my Oly .45 to buy a Thompson.  That was a uuuuuuge mistake.  I am feeling quite presidential right now.

What distance are you guys with 16 inch barrels sighting in your optics. I just finished assembling a rifle using one of Rudy's (AKA Mad-Machinist) 45 blowback builder's kits. I've always used 25 yards with my 9MM projects.

I have my D/I .45 (Aimpoint CompM4s) at 25 yards... I will probably try it at 50, 75, and 100 yards, to see what kind of drop I'm going to get. Depending on that, I may change my zero.

By my estimate, you'll be about a foot low at 100yd.

I modified a Lula to work with the GG mags.  I was having problems finding a USGI loader that didn't have ripoff shipping rates.  I had to remove the spring loaded mag guide and then hogged out all four inside surfaces with a dremel drum sander and a file.  It fits and loads quite well.  5 minutes later I ordered a replacement Lula from Amazon Prime. It would be easy for them to make a GG loader but there probably isn't enough market.

Macon Armory DI upper w 8" barrel.  The color is more ODish in person.


Attached File

Hey guys, read a lot of the thread and just wanted to confirm a few things:

1) is the cncguns lower still the best choice of lower for grease gun mags?
2) if you're running a Lightning Link would DI or blowback be the best choice?  I've heard of pistol caliber ARs being hard on them before.

If you plan to sbr it I would suggest looking at RMW XTREME  and their hybrid lower, it takes modified GG mags (slot cut for mag catch and there is no mag block to use just a spacer in the front of the magwell) and standard AR mags. It is the best of both worlds and only requires a single stamp. Even if you were not looking to sbr it, I think it is worth the ability to do pistol calibers and rifle calibers without the need to use additional mag blocks. I wish he would have had this years ago and I would have saved a ton in stamp fees...
I do not know about the lightning link, but the DI45 is going to run easier and not beat up the gun and no need for a super heavy buffer and spring. Recoil is surprising and lite, once I got my DI45 I sold my blowback.

475AR10

Thanks for that option, but I'm hoping to avoid SBRing as I'll be building a pistol.  My thought is it's legit to shoulder it once the RLL is in it, kind of like they do with HK sear guns that are pistols where they only put the stock on with sear in.  

On that note will a pistol buffer setup be sufficient for DI .45?

Rudy
I think I'll end up taking you up on that!  

Just to be clear, the MGI modular .45 magwell is vaporware right?

Check the EE for GG mags.  Some nice arfcommer had a stack of them and I bought some.  Very nice, brand new mags.  Very reasonable price.  

My .45 DI upper is still killing my ammo supply.  

Yes pistol buffer works fine, I have several with braces on them and they run great. I have one of RMW's hybrid lowers but have not built it out yet, but may do a brace on it as well?
Last I checked with MGI they did not have grease gun, large or small frame glock mag wells avaliable currently, that was back in January will jave to contact tjem again as I need the small frame glock to complete my collection. And yes the DI45 works great on the MGI as well. I like to be versatile with my lowers and change things up. That is one of the reasons I love the AR platform.

THREAD REVIVE WARNING!!!

I want to assemble a 8.5" maybe 10" 45ACP upper. Direct impingemment gas system. Have a 458Socom and Grendel uppers assembled from parts running successfully already.

What is a typical gas port location. I know pistol is still too long.

Gonna start at 0.125" gas port with a custom adjustable gas block so gas tube has a straight run.

I have a barrel blank coming from Green Mountain and a local machinist/friend who can perform all the work. Hes done 6X45 and 458Socom already.

I have a QC10 45ACP lower Grock mags!

Whats the word on the PSA .45ACP uppers?  Will they work with an AR lower setup for grease gun mags?

Rudy - Would your Blowback upper work on a CNCguns lower if I added a fixed ejector?

Problem #1 - I am in the semi-free state of CO still under siege and duress by oppressive Magazine capacity restrictions. - Well I have that partly solved as I bought my (NFA) Model 10 way back in the 80's and the pile (enough for all day long) of GI GG mags have all been fit to the MAC.

Now following the logical course of action I also bought lots of Magma and Dillon products to keep up with the demand for cast 230gr RNBB properly stuffed into bucket loads of 45acp brass. So let it be known all 45acp fired here in all platforms is cast lead. Correct me if I'm wrong - but I would think that shooting cast lead in volume might not fair to well with your DI system.

I have been wanting to build an SBR AR in 45acp, but due to current laws, it needs to be able to use GG mags.  15round GLOCK mags is not an answer.

I will be building my own billet receiver, so adding the fixed ejector, and all the SBR engraving and any other design considerations can be implemented before anodize.

Uhh...  I don't, like, "NEED" a .45 AR but I'm pretty sure I WANT a .45 AR.

The Macon parts look pretty good.  I could build a half decent LaFrance M16K .45 clone.  I've had one of his handguards sitting around forever.

"It's a trap!"

Ask me how I know.....

Rudy is awesome, I just bought a 45 upper and six magazines from him last month. Top notch service, dude knows his stuff.

Please any help on gas port location for a 7.5" to 10" barrel?

I have a feeling its gonna be right up next to the barrel nut but would like to hear from some of you guys running DI.


teaser pics

458Socom



45ACP project

Rudy, have you played around w/ 9x25mm Dillon?

I got to shoot one(9x25 Dillon) that Ron @ RMW XTREME  built for a gun writer a few years ago and what a round, with an 88gr solid copper hp it was doing 2400+ fps if I remember correctly and boy was it loud....  I think it used tok mags and he modded a few 223 mags with a ramp and spacer in the back and it ran well. I always thought it would have been a great pdw/sbr.