TFB Review: The Shooters Box 577/450 Chamber Adapter

As it happens, I like weird old guns. Ever since I watched the incredible Zulu (1964) a few years ago, I wanted a Martini-Henry. Specifically, a Martini-Henry Mk III, which is the model found in the movie. Mostly. They couldn’t get enough actual Martinis and had to use some Enfields, but it doesn’t matter. Unfortunately, the Martini-Henry is chambered in 577/450, a cartridge that is long out of production. Enter the Shooters Box 577/450 Chamber Adapter.

Martini-Henry Rifles @ TFB:

Image of the 577/450 chamber adapter from

a 577/450 Chamber Adapter

Now, to be clear, there is 577/450 ammunition out there. Boxes come up on GunBroker all the time, there are a few companies that occasionally do limited runs, and you can make your own. However, besides the fact that I’m not set up for reloading right now, I really don’t want to go through the process of forming 24-gauge brass to make my own cases. I know it’s doable, it just looks like a pain in the tuchus.

So it’s much easier to simply buy a chamber adapter. The Shooters Box makes two of these adapters. One for 45ACP, one for 45 Long Colt. I purchased the 45ACP adapter. The adapters retail for $69.95, but they appear to be on sale pretty much consistently for $20 off, with a final price of $49.95. Which, I’d say is a pretty fair price for what you’re getting. I’d certainly say that though, I bought one and have been enjoying it for a few months now.

The 577/450 Chamber Adapter inside the breech of the Martini-Henry.The 577/450 Chamber Adapter inside the breech of the Martini-Henry.

Adapter inside the chamber.

So how is it to actually shoot?

To make a long story short, it’s fun. It’s really fun. To tell the full story, there are some issues I ran into while shooting it, but the positives dramatically outweigh the negatives in my opinion.

The Problems

So first things first. The issues I ran into. Well, actually it’s one issue, one gripe, and one unfortunate reality. The issue is that the Martini-Henry’s firing pin is designed to work with late 19th-century primers, which were (to the best of my knowledge) uniformly hard. Which means that mine goes right through the modern 45ACP primers. Yes, through.

Punctured primers on 45ACP cases sitting on a table.Punctured primers on 45ACP cases sitting on a table.

Note the punctured primers

Yeah. It punctures every primer. Right through. You can actually see daylight through the holes if you hold them up to the sun. Now, I did not buy the 45 Long Colt adapter, and this issue may not be present with that round. This issue is not even present with every adapter. I went to the experts, The Martini Henry Society Facebook group, with my concerns. Yeah yeah, I know Facebook bad. But these guys know their stuff.

The consensus of the group was that the issue was partially due to the simple fact that this gun was made in 1880, and the standardization of parts was still in its infancy. My firing pin simply is “sharper” than many others, for lack of a better word. Ultimately, it’s not really a problem. It doesn’t present a safety concern and does not damage the rifle.

The Gripe

The gripe is that it’s super easy to accidentally send the adapter flying through the air like it just doesn’t care. The 577/450 Chamber Adapter is designed to be pulled out of the chamber by the extractor, just like a real 577/450 round. That’s good, it means that it’s easy to just tap it on the table to drop the spent 45ACP case and load a fresh one. Plus there’s just something about dropping the butt of the rifle to your hip, working the lever, and having a round pop out. It just feels right. But if you do it too quickly it’ll go flying. Which is terrifying the first time, and funny the second through tenth.

The Unfortunate Reality

The simple fact is that the 577/450 cartridge fires a 0.455″ diameter bullet, whereas the “modern” 45ACP (modern here meaning post-1900) and slightly less “modern” (technically just as old as the Martini pattern rifle) 45 Long Colt fire a 0.452″. That missing 0.003″ means the bullet simply will not properly engage the rifling. This has two effects.

First, you’re not getting a lick of accuracy out of this without hand loaded soft-cast rounds. Which, if that’s something you’re willing to do, great! This will not be a problem for you. If, like me, you’re probably just going to feed modern ammunition through it, well prepare for key-holing at 10 yards.

Second, back-pressure. There isn’t any. Which leads to…

Bulged primers in 45ACP cases.Bulged primers in 45ACP cases.

Note the bulged primers.

Yeah, the primers don’t just get punctured, they bulge out pretty noticeably. Ultimately this isn’t a huge issue. It actually led to the brass self-de-priming a few times, so if you’re a reloader it might even be a plus.

The Good stuff

This is just fun to shoot. I mean, holy crap. Firstly, 45ACP out of a 33.22″ barrel has absolutely no felt recoil. Seriously, it’s like shooting a 22. Secondly, It’s also if not hearing safe then really close to it. The noise the round makes is almost a cute little “pop” and my buddies and I got a kick out of hearing it over and over again.

I can’t stress enough just how fun this was to shoot, and unless you’re willing to form your own brass out of 24 gauge, or spend $15 a round on GunBroker, this is really the only way to actually get to shoot your Martini-Henry.

Ain’t she a beaut?

I love this gun. It is Fun with a capital F. Working the lever, sighting down the (extremely rudimentary) iron sights, you can feel the history just oozing out of it. It’s part of the reason I adore milsurp guns. Anything that takes one of these old warhorses and makes it economical to shoot again is a good thing in my book.

So in my estimation, this is 100% a buy, if you’re not going to be making your own 577/450 rounds. What do you guys think? Let me know in the comments.

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