SVT Mag Cut-down

I've heard from a couple of folks with Globe 555 magazines.

With the understanding that I may need to tweak the feed lips and possibly nick a bit off the bottom of the follower to account for the "5 .303 rims are smaller than 5 7.62x54R rims" effect, I'm starting to think I should just buy one of those and make it work. I've only a few pictures, but the conversion looks like it was fairly well carried out.

Ulrich
 
I have a 5 round cut mag, as well as other full size mags, and I prefer a cut mag for hunting. It sticks out less and its easier to carry the rifle. I got my cut mag from Westrifle.
 
So I picked up a repro mag 2nd hand from a fellow who had bought it from <redacted because the quality is very poor> and couldn't make it fit into his rifle.

I'm about 4 hours into trying to make it fit into mine, and this thing is just not built right!

On the bright side, I feel no trace of guilt about cutting it down.

Depending on how it goes, I may end up sledgehammering the thing flat out of frustration, and I will feel no trace of guilt over that either.
 
The shortening was easy, but getting this nasty-cheap repro to fit has used up just about all the patience I have.

A couple of things:
1) The native 5 is about the same length as the trigger guard. I like the appearance.
2) Getting the retainer lugs into the right place is an easy iterative file-and-check process. Don't be frightened of it, just take small cuts and repeat. The retention on the new one is better and more positive than the original.
3) A steady hand with the propane torch will let you solder/trim the feed ramp repeatedly if you need to.
4) The native 5 does not stick out past the release lever, meaning that you'll want to add a couple of ridges onto the sides to help with gripping it.
5) Cutting out the limiter before reducing the chassis length will make you guilty of a federal offence, so make sure you do the steps in the right order.

And if you want to try this, try it with a good repro. Not the POS I started with.

I have it assembled, but the thing refuses to feed reliably. This is unrelated to the shortening process. If I can get it to work I'll paint it and post pics.
 
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>get you a new one

If I get it working I'll want to keep it, but I'll happily post pics.

If I can't get it working, you won't want it (partially because of that sledgehammer thing I mentioned earlier).

I need to meditate a while on the mechanics of how rounds feed up into the breech. There are forces in action which I don't perceive yet.

Alternatively, you were once the owner of <the company that imported these repros originally> and are still racked with guilt over their abysmal quality, in which case PM me and I'll help you do the right thing.
 
Does anyone here want to share their observation/understanding of how the magazine geometry gets the tip of the top-most round to center and raise itself?

The rim is being handled properly, but I don't have the right lift on the tip.

Is it a matter of pinching the stack in at the front so that it turns from a wide-short-double to a thinner-tall-double?

Or is it a function of the angle of the top surface of the follower?

>deer hunting with mine last Fall

Iron sights or optics? Stalk, stand or drive?
 
I know I'm a year late to this party, but a machinist and a welder...hmmm... Why aren't you just making a 5 round magazine? It's just a spring and some bent pieces of metal.
 
I know I'm a year late to this party, but a machinist and a welder...hmmm... Why aren't you just making a 5 round magazine? It's just a spring and some bent pieces of metal.

There are many subtle aspects to the shaping of the metal.

Good repros can be had for c$100. I'd spend many times that before got the dies right, and I only need one.

If I'd started with a good repro this would have been quick and easy: 2 cuts, 1 tig weld, snip the spring, prep and paint. Done.

It's been educational.
 
All 5 feed now, as long as they are pointy enough to clear the breech face.

On the other hand, the bolt hold open doesn't work reliably. And my left index finger is down for repairs for a few days, which is how I became aware that the bolt hold open had stopped working reliably. I added metal to the follower to reliably engage the BHO, but that required cutting away more of the rib that runs along the back of the magazine. And then the offset force binds the follower, which can't be helped because the mag walls are so ratty from all the adjusting (ball peen style) I've had to do. So, no more BHO.

The rib, by the way, was welded, and they didn't grind down the inside, which means that there was an uneven surface on the inside of the rib which catches on the BHO protrusion. It complicates the dies, but that rib should have been pressed out of the surface, with the only joint being at the front end.

Also, I think the follower top is wrong, in that it is noticeably different from the surface of the next-round-down would present, which complicates the feed lip tuning. In my understanding the follower should look just like the next-round-down in terms of contact angles.

Next I grind/clean/paint. Then I'll take pics.
 
Here are pictures of the finished unit installed.

IMG_1810_zpsqbykvghe.jpg

IMG_1811_zpsiw62bs8h.jpg

IMG_1812_zpseigcfxt0.jpg


My metal-joining skills are not good enough to butt-weld the flats, so I put on doublers to reinforce the joint. If I was doing this again, I'd locate the seam and doublers further down so that they don't rub on the mag well sides.
 
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