Building a Hybrid Yugoslav M70B1 from a Stub with Screws

Building a Hybrid Yugoslav M70B1 from a Stub with Screws

George Spafford is building a replica of the Yugo M70B rifle using a stub parts kit. A new installment will appear here every Friday

Fabricating the Trunnion—Part 3

When compared to an AKM trunnion, it was clear the stub needed to be cut behind the left shoulder and then ground to 1.25 inches below the "shelf" where the barrel pin was pressed in. The planning and marking of the trunnion is critical. If you are not square, you can end up with a trunnion that is unsightly or even dangerous. Take your time and literally measure twice or even four times before you ever cut.

Angle iron is securely clamped to create a guide to cut the grove for the sheet metal lip to press into. By doing this first, it also creates a straight guide edge.

To show this could be done, I pressed out the barrel pin and barrel to get them out of the way as previously mentioned. From there, I used my Harbor Freight bandsaw to cut the front trunnion to length, scribed the lines with a square and then hand ground the trunnion to the correct width. I did this with a 4.5-inch grinder to do the rough work and then files for the fine work. I took care not to get the metal too hot and ruin the heat treat.

One side of the trunnion has the initial rough grinding done. The straight edge is there to protect the finished upper shelf of the trunnion from being nicked by the grinder. Yes, a mill would have been easier, but using hand tools seemed like more of a challenge and it worked out just fine.

I only trimmed enough from the bottom to slide the new trunnion in, as the "ears" would be needed to secure the milled lower handguard. Sure, I could have used my mill but this handwork method seemed like a more basic approach that I had to try. It took a while but the results came out to my liking.

All the fine shaping was done with coarse and fine files. Yes kids, in this age of power tools, good files still come in handy, as you can see in this photo, a pair of Nicholsons. The machinist's square and piece of scrap receiver were used to check progress. To fit into the receiver, a little shaping was done on the bottom of the trunnion as well.

To give a solid surface behind the sheetmetal receiver, the milled stub's lightening cut was filled with JB Quick Weld and then sanded flat. So far, by the way, this "filler" has held up just fine, no doubt because there isn't any load on it. The ends of the stub were ground to create slight angles to mimic the AKM trunnion. The result was a perfectly useful trunnion that would fit in a standard AKM receiver.

If someone had a rear receiver stub, the same basic principles would apply. Cut it down to size, grind to a 1.25-inch width, locate the holes and drill them out. I'd recommend using 1/4" screws given the recoil the rear trunnion would need to absorb.

Recommended for You

2nd Amendment

Tell the White House that the 2nd Amendment Was Not Given to the People by Government

Firearms News - July 02, 2019

Please sign and share the petition to get the required 100,000 signatures by July 27.


Berger 6.5mm 156gr EOL Elite Hunter Bullets Available Now

Berger Bullets - July 10, 2019

Berger Bullets is now shipping the new 6.5mm 156gr EOL Elite Hunter projectiles to exclusive...

2nd Amendment

Firearms News Investigates the NRA: Part 1

Nedd Scott - July 18, 2019

This will be the first of many investigative reports about the NRA by Firearms News.

See More Recommendations

Popular Videos

Ruger introduces Rifles Chambered in the All-New .350 Legend

Two Ruger American Ranch rifles and the AR-556 MPR are now chambered for Winchester's .350 Legend cartridge.

American Suppressor Association (ASA)

ASA is the unified voice of the suppressor industry and a leading subject matter experts on suppressors and suppressor related advocacy.

Performance Center M&P Shield M2.0

From Smith & Wesson, the M&P Shield M2.0 is a great option for a carry gun with optics option.

See more Popular Videos

Trending Stories

2nd Amendment


John Peterson - May 22, 2019

Rhode Islanders are setting brushfires for freedom once again as they advance a Second...


World War II German Elefant Tank Destroyers

Neal S Shera - July 12, 2019

The last of Germany's infamous Elefant tank destroyers.

2nd Amendment

2020 is Trump's to Blow with Gun Owners

David Codrea

No one can restore receptivity to another Trump term with these disaffected gun owners but the...

See More Stories

More Gunsmithing


YouTuber Builds AR-10 Receiver from Used Brass Cartridge Cases

Jim Grant - July 06, 2018

YouTuber, GunCraft101, builds an AR-10 from used brass casings.


Building a Heavy AR-15 Varmint Upper Part 2: Barrel Assembly

Gus Norcross - December 31, 2013

In the second part of this series, we examine how to build the barrel assembly on an AR-15...


AGI Glocksmith Course

SGN Online Editors - April 09, 2014

AGI's new Certified Glocksmith Course includes Complete Disassembly & Reassembly, the...

See More Gunsmithing

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction.


Give a Gift   |   Subscriber Services


GET THE NEWSLETTER Join the List and Never Miss a Thing.