Skip to main content

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

Install the Barrel — Part 2

The Yugo extractor protrudes from the front of the bolt significantly. Therefore, the bolt must be stripped to headspace the rifle accurately. Stripping the bolt is actually very easy and simply requires a small punch and hand pressure to remove the two retaining pins.


Once the groove in the barrel for the pin aligns with the holes in the trunnion, it is time to check headspace. It is always a good idea to use real headspace gauges to be safe. If there is too much headspace, the resulting slop on the end can cause cases to bulge and even rupture. When I first started building AKs, I invested in a set of Manson Precision Reamer gauges — Go, No-Go and Field. They have worked great for me over the years and are a good investment.


With the Yugo bolt, the extractor is so large that the bolt must be disassembled to test headspace. Despite looking daunting, the M70 bolt actually disassembles with hand pressure by removing first the bottom pin and then the crosspin. I like to do this on a table to make sure I don't lose any little parts and then I put the parts in a container out of the way. A little organization can save some grief down the road.

Use a small tray to hold the bolt parts. They are small and very easy to misplace.

I like to perform headspace tests with just the bolt and no carrier. This way I can see exactly what is going on. First, I use the Go gauge to verify that the bolt will close properly. I insert the gauge in the chamber and then slide the bolt forward rotating it so the lugs begin their lockup.


The bolt should be able to rotate fully. If it does not, the barrel must be pressed back out. Methods include a long bolt with a double brass nut on the end to protect the breech, the use of a long socket extension with a stack of copper pennies taped on the breach to protect it and so on.

Second, I use the No-Go to verify there isn't excessive headspace. Again, I insert the gauge in the bore, install the bolt and proceed to rotate it. The bolt should stop short of full rotation. Now this is an estimation on my part, but I would say mine stop at around 80-90% of the rotation. We're talking differences in the thousandths of an inch, so I really am watching to make sure it doesn't go all the way — that is the important part. If it does, then the barrel must be pressed in further.

Most likely, with a worn M70 like mine, you will need to press the barrel in further. Any time you change the location of the pin from the original means you will need to use an oversize pin. This is done by making sure everything is in the right location and then drilling a new oversized hole with a sharp cobalt bit that is .002" smaller than the pin.


For this build, I had too much headspace, so I pressed the barrel in and opted to use 19/64 (.297") drill rod and M size drill bit (.295"). Once it was pressed in, I confirmed the headspace one more time before moving on. It's always good to play it safe.

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

Recommended Articles

See More Recommendations

Popular Videos

SilencerCo MSR Hunting

SilencerCo MSR Hunting

Hunters, save your ears! Patrick Sweeney reviews suppressors from SilencerCo.

Citadel Boss 25 Shotgun

Citadel Boss 25 Shotgun

Dr. Will Dabbs tells you why the Citadel Boss 25 is the way to hunt birds or deer with a shotgun in the 21st century!

See More Popular Videos

Trending Articles

One New York lawmaker is pushing legislation to bypass the Protection of Lawful Commerce in Arms Act (PLCAA) and allow gunmakers to be sued if their lawfully made products are used for criminal purposes.New York Targeting Gunmakers Instead of Criminals 2nd Amendment

New York Targeting Gunmakers Instead of Criminals

Mark Chesnut - August 19, 2020

One New York lawmaker is pushing legislation to bypass the Protection of Lawful Commerce in...

The Leupold VX-Freedom AR scope line hits the sweet spot on frills, performance and cost to you.Leupold VX-Freedom AR Scopes Optics

Leupold VX-Freedom AR Scopes

Jim Angell - August 18, 2020

The Leupold VX-Freedom AR scope line hits the sweet spot on frills, performance and cost to...

Anarchy Outdoors has introduced a series of upgrades for the T/C Compass and Venture rifles.Anarchy Outdoors Introduces Upgrades For T/C Compass and Venture Rifles Rifles

Anarchy Outdoors Introduces Upgrades For T/C Compass and Venture Rifles

Firearms News Staff - August 22, 2020

Anarchy Outdoors has introduced a series of upgrades for the T/C Compass and Venture rifles.

For the first time in its 35-year-history, the annual Gun Rights Policy Conference hosted by the Second Amendment Foundation and Citizens Committee for the Right to Keep and Bear Arms will be a virtual online event, due to the current COVID-19 situation.2020 Gun Rights Policy Conference Is Online Event Due to COVID-19 Industry

2020 Gun Rights Policy Conference Is Online Event Due to COVID-19

Second Amendment Foundation - July 16, 2020

For the first time in its 35-year-history, the annual Gun Rights Policy Conference hosted by...

See More Trending Articles

More Gunsmithing

On the bench in front of me was a customer's M&P Shield he'd dropped off complaining about theApex M&P Trigger Kits Gunsmithing

Apex M&P Trigger Kits

Gus Norcross - July 11, 2014

On the bench in front of me was a customer's M&P Shield he'd dropped off complaining about...

This fixture holds Mauser receivers and barreled actions in a bench vise, drill press or millingBrownells Mauser Receiver Holding Fixture Gunsmithing

Brownells Mauser Receiver Holding Fixture

SGN Online Editors - August 12, 2014

This fixture holds Mauser receivers and barreled actions in a bench vise, drill press or...

AGI's Certified AR-15/M4 Riflesmith Course includes DVDs with Complete Disassembly and Reassembly,AGI AR15/M4 Riflesmith Course Gunsmithing

AGI AR15/M4 Riflesmith Course

SGN Online Editors - July 06, 2014

AGI's Certified AR-15/M4 Riflesmith Course includes DVDs with Complete Disassembly and...

There was a time (a couple decades ago) when most 1911 front sights were staked in place as JohnHow to Stake a Trijicon 1911 Front Sight Gunsmithing

How to Stake a Trijicon 1911 Front Sight

Gus Norcross - May 29, 2014

There was a time (a couple decades ago) when most 1911 front sights were staked in place as...

See More Gunsmithing

Magazine Cover

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT ISSUE Arrow

Buy Digital Single Issues

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the Firearms News App

Other Magazines

Special Interest Magazines

See All Special Interest Magazines

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

Phone Icon

Get Digital Access.

All Firearms News subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now