AMT large frame backups
Printed From: AMT Guns information
Category: Auto Mag Pistol
Forum Name: Message Board
Forum Description: Message Board
URL: http://www.amtguns.info/forum_posts.asp?TID=3031
Printed Date: 27 Mar 2026 at 4:35am
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: AMT large frame backups
Posted By: Patak-Phillips
Subject: AMT large frame backups
Date Posted: 17 Nov 2025 at 12:09am
| My question to the group is, if I have an AMT BACKUP .45, can I just change the upper, barrel and magazine to another caliber (like 9mm or .400 corbon) and it will function? |
Replies:
Posted By: Rumore
Date Posted: 18 Nov 2025 at 9:10pm
|
I don't know about all the various/possible swaps, but I did take a 40 SW, installed a 9mm barrel, and rechambered it to 9x25 Dillon. It worked fine. I also rechambered several 40's to 10mm as well. I have a bunch of large frame Backup top ends if there is something you are looking for, drop me an e-mail to Tony.Rumore@Tromix.com Tony Rumore Tromix ------------- Run it up, until you blow it up, then back it down a bit. |
Posted By: Patak-Phillips
Date Posted: 18 Nov 2025 at 9:37pm
| Thanks for the response, I've been carrying a .45 backup as my CC for years and had been looking for a .400 CorBon pistol for about 20 years, was just at Wannenmacher and found the gentleman who bought out all of what was left of the parts from galena, and lo and behold he had a slide and barrel for .400. Might be interested in a .40 or a 9mm upper if they are galena, not irwindale, so it matches the pistol I have. |
Posted By: AMT addict
Date Posted: 20 Nov 2025 at 12:59am
|
I am pretty sure they will although I have never tried a swap. I know the firing pins have different thicknesses on the the end that hits the primmer between some calibers but that is part of the slide. Fyi just a good thing to know is that if you have say a 9mm firing pin break off. Interarms still produces 45 acp pins and you can drill the hole a little bigger and drop in the thicker one. Now I have to speak on the Wannenmacher worlds largest gun show. I have not been 5 years or so, wish I had found that guy when I was there. That gun show is just flat out unbelievable. You are tired of walking by the time you get from your parking spot to the front door. The first time I went, I walked the down stairs then was like, well it looks like a few rows of overflow upstairs so lets check it out. Got up the stairs and the place is packed almost as far as you can see. The downstairs is maybe a third of the size of the upper area. We are talking about an 11 acre building packed wall to wall. If the walk the whole show, your arms and legs feel like they are going to fall off by the time you make it back to your car. On Sunday a good 2 hours before closing you will start seeing sellers starting to pack. I can only imagine what it take to get all of that set up and hauled back out of there. Here is a couple of facts about this show. If all our tables (2800 8ft. and 1300 6ft.) were placed end to end they would stretch 5.7 miles! If you spend the whole 18 hours we are open to the public and divide that by 4,200 tables, You will have 15.4 seconds to look at each table. |
Posted By: AMT addict
Date Posted: 02 Dec 2025 at 4:57am
|
I have some info to share on this. I bought a 357 sig Galena made upper from Tony. 1st I tried to put it on an Irwindale 45. It slid on until it reached the ejector and would not clear it. Have more pictures to share but not up to fighting them all to upload right now. Next I tried it on a 9mm Galena. It fit, using 40 cal mags, 1st wouldn't feed tab all. Had to lift front of bullet to chamber. 2nd mag wouldn't feed 1st of 5 but with 4 rounds they would feed. 3rd mag all 5 fed just fine so if you worked over the lips some it might get there or maybe just not good mags to use with using as 357. Next I decided that I would put the 357 sig on my Galena 45 since I oak more likely to shoot the 9 over the 45. Well that didn't work out. If I left the pin out, the slide would go all the way back however when I put the pin in, the slide wouldn't go far enough to push it in the rest of the way. Finally figured out that the barrel wasn't dropping enough and was catching on the slide. Now with some gunsmithing, it could probably be made to work. So yes you can change calibers but it may need some work to get all of them to work on the same frame. Sticking with Galena made ones sounds like a good plan. Although they look the same I continue to find differences. Wish I knew why they made they changes that they did. It turned my picture so lets say the front gun is a Galena and back is Irwindale. You can see how different the ejectors are. Original amt stands a fair bit taller and that is way the Galena slide wouldn't go on. Not to say that it couldn't be made to work with some gunsmithing.
 |
Posted By: AMT addict
Date Posted: 06 Dec 2025 at 2:48pm
357 sig Galena on AMT Irwindale frame. It would take more than just a little filing to clear the elector.
|