Editors Note: Based on how these blocks performed when we actually used them to press in the barrel. We made some changes, hopefully those who rely on this write up will appreciate the changes made. Please reference the new assembly prints found here.
Common to many AK pattern rifles, the barrel is pressed and pinned into place, rather then threaded into a receiver. This presents a few challenges, that wouldn’t be an issue if we were building an AR or a Remington 700. Namely we need to support the barrel and receiver and press it together, all while keeping the barrel timed so the gas block and sights end up precisely at 12 O’Clock.
I have come across YouTube videos that show the assembly of barrel and receivers in a horizontal press. The receivers are heated, and set into a fixture. The barrel is pressed into the receiver in one swift motion. Pretty slick, not something I can reasonably replicate with the equipment I have.
I have spent a considerable amount of time thinking through how I want to do this. I am not going to advertise this as a best practice, or even the correct way. It’s just the way I decided to do it. If you have seen better ways, or know of a better way, by all means let me know. I’ll be glad to include it for others to read.
One of the first things I need is some way to support and hold the barrel in place so I can press on the receiver. Brownells sell barrel vises that are designed to clamp on a barrel and support it during installation and removal. These are built to last, and having used a couple, they are well worth the money. However I am hesitant to spend the money, I’m already into this project a little more than I wanted to be.
I decided to try and build something that can be used once to do the job that I needed. This would provide me with a little experience fabricating. Something I both enjoy doing, and would like to do more of.
The design I came up with is pretty simple. It’s not really a vise, a more proper term is probably barrel blocks.
I made the pieces long so that I have room to clamp them to the press. Mouth of the hole is taper to closely match the radius on the barrel. The rest of the hole is sized so that it clears the barrel.
The steel I picked up is .375×1.5 by 36in long piece of hot rolled mild steel. Probably 1018 or something similar. Honestly for what we are doing, I didn’t feel the steel needed to be anything special. I also assumed I vastly over paid for it since I bought it at Home Depot.
The way I chose to cut the center might be the subject of some controversy. I don’t want anyone to be under the illusion I am a master machinist. However I am learning. I don’t have access to a mill, but I do have access to an old engine lathe.
I did not spend hours trying to get this exactly centered and I fully expected to break at least one or two drill bits trying to do this. I went slow, turned the lathe at ~50rpm, and fed in the bits quite slowly.
I spot drilled the hole and then got the pilot hole drilled with 5/16 bit. From there swapped out to a 1/2in bit. This gave me a hole large enough to use the lathe tooling I have.
Enlarging the hole to the final diameter was not something I am proud of. The lathe tooling I have access to is too small and the lathe is quite loose. The cuts were slow, and the surface finish was awful. However I took my time and I triple checked the clearance on the headstock each time I made an adjustment to the carriage.
At the end of the day I was left with exactly what I wanted. A means to hold the barrel upright so I could press the receiver in place.
This puts me one step closer in getting all the tools needed for pressing the barrel onto the receiver. What is likely a process which will take five or ten minutes, has taken me a few days of thinking and a few solid hours of fabricating. In the end, I’m betting the prep time will have been worth it.