Yugo M72 Rear trunnion modification to M70

[ElectronWrangler]

Has anyone ever tried to modify a M72 Yugo rear trunnion to have the recoil spring retainer slot that the M70 has?

If so how did it turn out?

[Richard Erichsen]

Has anyone ever tried to modify a M72 Yugo rear trunnion to have the recoil spring retainer slot that the M70 has?

If so how did it turn out?

I did it on one M72 rear trunnion because I found, probably as you have, that the M70 trunnion with the locking pin are pretty much unavailable. The ONLY difference is a hole drilled through that is sized slightly larger than the pin with the spring around it. With the rear trunnion loose in the folded receiver, you can mark the position of the pin and start by drilling your pilot. I no longer recall all of the sized bits I used, but the steel is soft and was not challenging to drill, even with a block of wood and a hand drill.

I ended up building without the M70 top cover, so the pin wasn't needed and the locking pin holes ended up welded over. Given that my M70B2s will never fire rifle grenades and the whole purpose of the locking cover feature was to keep the top cover from popping off while firing rifle grenades, it's probably more trouble than it's worth.

If you are hellbent on a top cover locking feature, CNC Warrior sells new locking pins with spring for around $20. Very often if you can find the top cover, or even the rear trunnion, the locking pins are missing and usually sold as a separate part.

Take a moment to consider if you really need or want the feature in a semi-automatic rifle that can never be fitted with the grenade spigot, isn't a whole lot of fun to use with the gas system disabled (grenade sight raised), a blank in the chamber and an M60P1 inert grenade fitted to the end of the spigot, at least not while you live in California. If you leave the state, perhaps then all the trouble might be worthwhile.

R

[69Mach1]

M72 rear trunnions are rare. Please don't do that. Trade for an M70. You won't have a hard time finding someone.

[ott1]

M72 rear trunnions are not rare. Apex has plenty.

https://www.apexgunparts.com/product_info.php/cPath/21_102/products_id/1610

I have a spare M70B1 rear trunnion that is made by turbothis that I probably won't be using. PM me if you're interested.

[Richard Erichsen]

M72 rear trunnions are rare. Please don't do that. Trade for an M70. You won't have a hard time finding someone.

I respectfully disagree. I don't deal with gun auction sites, so while M70 rear trunnions were essentially impossible to find, the M72 rear trunnions I could find on three different sites with ease. I could buy a dozen M72 rear trunnions right now from Apex Gunparts for a decent price if I felt so inclined, as Ott1 mentioned.

It's only steel. Drill a hole, weld over a hole, it's probably the least risky change there is on these rifles.

R

[tujungatoes]

I'm gonna go ahead an assume he read it wrong and thought you said M92....or maybe he had a stroke today....you feelin' ok mach?

I'm pretty sure mach was the one who told me about the m72 parts at r-guns when I was piecing together an M70 fixed stock kit. BTW they have 'em for $5 cheaper than apex.

[Richard Erichsen]

I'm gonna go ahead an assume he read it wrong and thought you said M92....or maybe he had a stroke today....you feelin' ok mach?

I'm pretty sure mach was the one who told me about the m72 parts at r-guns when I was piecing together an M70 fixed stock kit. BTW they have 'em for $5 cheaper than apex.

R-Guns is the only place I found that had those fiendishly hard-to-find bulged barrel trunnions. I bought 6 ultimately and have pressed 5. The sixth was an oversized "4" that sits in my junk box that I should have had the sense to return. I could have returned it (R-Guns aren't too bad about that), but I was overly optimistic I'd use it and not be defeated by it. I'd need to have an oversized barrel/profile a barrel from a blank to use it or access to a MUCH better "pinch" type knurler. A regular dimensioned barrel could be twisted by hand in the trunnion even after raising a good surface on it.

M72 parts outnumber the M70 parts at least 10 to 1 right now. If you can buy a complete kit, this isn't an issue (other than cost), but I haven't actually bought a "kit" myself yet, just loose parts. If you find a better price for the M72 part, buy it. The bolt groups, trunnions, front sight blocks, pistol grips, buttstocks, small parts like pins and so on are the same. I bought M72 bolt groups for my M70s for a 15% discount at Apex even though they are the SAME parts.

R