PSL 20 round mag mod

I'm in the process of trying to modify a 20rd Lahti 7.62x54 mag for use in a PSL. As there seems to be little information of how this done I thought I'd document the work "in progress" as I went along. Hopefully it's of value to others.

I'm a bit busy right now to give a long write-up...hopefully the pics will suffice for now. All work was done with a cut-off wheel and grinder. A mill would have been nice....

Pic 1: Both mags with feed lips removed. Note that I left the locking tab on the back of the PSL mag. The Lahti mag will still have to be cut to accept this



Pic 2: Lahti mag body, PSL follower and PSL feed tower. Note that the rib on the PSL follower has been removed to allow it to fit in the Lahti body.



Pic 3: Comparison on the PSL feed tower geometry against the Lahti body. There'll be a little work here but should be doable. Also note the thickness of the back of the Lahti mag...this thing is built like a tank...



Pic 4: PSL follower in Lahti body. Seems to move in an acceptable manner and angle looks good.

Like Your Thinking!

Any update on progress?

Not yet. Been overseas and am just getting back. It went to the welder about two weeks ago.

Cool.

Glad your back safe.

I look forward to pics cause I'm on board for trying something like this.

Ok. Just picked it up from the weleder yesterday. Haven't had a chance to test for fit as the rifle is off getting tuff-coated.

Did try to load it up and already can tell it will take a bit more tweaking. I'm using the PSL follower at it appears that it's getting "lost" in the bigger Lahti body. May end up building an extension for the follower that widens it a bit and maintains the correct feed angle.

Anyways, here some pics

You will probably need to do some considerable tweaking to the follower...I did with mine. Chopping and fusing are the easy parts.

Good Idea!. A few members here have done this . BTW Centerfire has PSL mag bodies available on the cheap. Also not to make a mess but why the bad welding job towards the front of the mag. Should look like a stack of nickles like it began. Seems like the welder burned through then filled it.

The weld was due to the fact that the dimensions of the PSL feed tower differed significantly from the Lahti body. Where you see that messy weld is where we had to fill in some large gaps with weld.

I just hit the front and back of my mags and didn't bother with the sides. They could be welded, but they fit pretty close and I'm not concerned about it.

So how much have you got to test it. If you want to let one go for "testing" let me know .

I've shot the hell out of the ones I have made. They heat up the 16" carbine and 9" pistol I have in a hurry. I wish the ammo was still $50 for a case.

Surly, can you post some technical pics of the mags you modded? I'm interested in the mods to the followers.

Also, I'm now thinking it might be easier to just weld two PSL mags together and use the Lahti spring. I believe that you did that as well....true?

I did the same thing you did on my second set of mags. The first ones were modded DP-26 mags and I wasn't able to get them 100% between the two firearms I have. I don't have any pics on hand and I might be able to do that next weekend...no promises though. If you go the route of fusing two PSL mags together, it might be a little easier, but your capacity will be around 15 rounds and you won't get the embossing to match.

Let me guess, you're having problems with the protrusion for the bolt hold open on the back of the follower. The follower can be a real bitch to get right and its the heart of the mag.

There has to be someone that will make a run of these. Plenty of people own them

That would be ideal.....especially for 922r compliance. Any ideas on who ?

If its US made it meets 922 R correct? US Palm Maybe?

Yes....if wholly made in the US it would count for 3 compliance parts....floor plate, follower and body.

Did you make any progress?

Been in a one legged man ass kicking contest....too busy right now to mess with this. Do you have any pics of the mods you did on the follower?

I've been busy as well and haven't gotten any pics. I don't think they would show though, as most of the mods were done by tweaking in the vice. It was a tedious pain in the ass, tweak, put together, load, unload, take apart, tweak...so many times I forget.

If I get some time, I have a few more donor bodies that I need to convert. I'll have the camera with me when I do.

New to the thread, but is there a specific reason to try and put the PSL follower into the Lahti mag instead of using the Lahti follower?

Or grinding down the top of the Lahti follower and then JB welding the top of the PSL follower on top of it? That would eliminate your binding issues, and since the Lahti is already 7.62x54 it should still stack correctly.

Could you just cut the upper off one PSL mag then weld it to another mag that has had the bottom cut off?

Guys you know as much as I do.....yes, the test will include two PSL mags welded together. Also will continue to tweak the current config. The solution of melding the two followers is interesting as well.

Is anyone else working this mod? Is so it'd be great if you could post your finding....sort of the JAMA for PSL mags...

I thought that there was a mod that one could do to Bren magazines to make them work in a PSL; I guess the 7.62x54R and .303 are similar enough in dimension for this to work?

SOmeone here has already done the grunt work. They have an PSL pistol in 54R with a 20 rd mag.

re: Welding two PSL mags together

On the MAS 49/56 rifle it was a common modification to weld two of the 10 round mag bodies together. Two original springs were placed one atop the other inside the modified body with the base plate insert sandwiched between the springs––this prevented the springs from getting tangled. Then the "new" spring was tuned by cutting coils off, usually one or two. The resultant mag would hold 18 or 19 rounds. The bugaboo for this mod was getting the interior of new mag body perfectly smooth, otherwise the spring would hang up.

I would think this would be a good route for making a hi cap mag for the PSL.

That would be me.

Anything is possible. The MAS mags have a heavier steel that makes up the mag body and they have fewer reenforcing ribs. It would take some work, but they could be fused together and straightened out after the heat causes a little warpage.

The PSL mag is a double-position feed and the Lahti mag is single making the follower narrower than that of the PSL. It won't work...I tried it.

Why can't we just do a coupler with a mod mag and a regular mag?

My idea: I can't make it because I do not have a mill.
Someone can tho....

You could even weld them together like that. It'll look funny, but if you're happy...

Have you tried Bren Mags? I found them for 7 bucks each

Not yet. I have a few and they will need to be fused together like the DP's, as they are too big where they insert. I'm thinking the BHO feature on the follower could be retained though.

I'd have to say the 1IV's idea ref fusing 2 PSL mags, bottom to bottom, seems to appeal to me. I haven't had a chance to muck with the Lahti mag mod but I can say with confidence that it will be a pain to make work. The PSL mag mod seems to have merit.

You can test drive it by using some duct tape to see if it feeds. I have some black shit at work that I might give a try. it will be strictly from Planet Shitball, but you'll know whether or not you'll get the desired results before making an adapter or fusing two together.

I wonder if you could just make a clamp like magpul does to extend it . Put mags bottom to bottom but test with tape like others have said and then use a clamp shaped to the mag body. Put it ass to ass.

Yes, I think you can and that's what I plan on doing when I can find some time to mess with this again. I'm planning on using 2 blocks of wood and dado an appropriate groove in each block, extend the blocks by about an inch on each side and use stove bolts/wing nuts to clamp it all together.

I've done the end-to-end fusing trick. You'd get ten in, and then the tips would start creeping down; however, I was using the original spring. Sometimes tapping the magazine would make rounds move into place, but it was too unreliable.

I've seen another version of it, someone cut the feed lip section off a mag, and welded that directly to the bottom of another. Still doesn't sound very reliable.

If someone has longer, stronger springs, they should give it a go. I'd like to know if two have a high enough degree of curve.

High leg of spring toward muzzle.

how hard could it be to make a jig to bend up larger mags from scratch for this?

Have you ever tried it?

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