This was the most stressful part of the build for me. I had never pressed a barrel onto a receiver before. I had done quite a bit of reading on how this went for other people and what suggestions they had. Some people would freeze the barrel, and heat the receiver, others did not to hardly any prep work. Some people stated that the barrel pressed right in without issue, and others claimed that it pressed in away before sticking.
With such varied feedback, I took the approach of being extremely cautious about how I approached this. This is why I spent a considerable amount of time building fixtures and jigs to try and address some of the concerns I had. Not everything went as smoothly as I would have liked but we got it done.
Once the barrel was timed, I didn’t waste any time getting started on prepping for the press. The slickest lube I had on hand was the lube I use for bullet swaging. This is bought from Corbins MFG. It comprises 50% Lanolin and 50% Castor oil. It’s a simple recipe but it works well for bullet swaging where the pressures involved are a great deal higher then what we will be dealing with.
I coated the barrel and the inside of the receiver with a thick coat of lube.
Before I set the barrel in the receiver in the barrel blocks I placed the barrel on the receiver, lined up the timing marks, and gave the end of the barrel a few firm hits with a dead blow hammer. The barrel started right into the receiver about 1/4 inch. This built my confidence that this press wasn’t going to be as difficult as I feared.
to begin the press. The astute among you will see where this might go wrong.
Before starting the press, I inserted the bolt, the locking lugs and the Go headspace gage. Now, I did not put the bolt carrier on, had I done that it would have prevented another problem that we will address later. However the theory is that as the barrel is pressed into place the Go gage will be pressed up against the bolt face and this will stop the barrel from moving further back into the receiver.
The word of caution here that will save you trouble. Make sure the locking lugs are fully locked in place. If you slide the bolt carrier over the bolt/lug assembly the carrier will do the work for you. If you are like me, and put the bolt open to check the progress ever so often, then make sure everything get’s seated back before you resume pressing.
Everything pressed together really well until I got to the last 1/2 and then it tightened up. I learned a lesson, C-Clamps were not enough to hold the barrel blocks in place. The force would spread the blocks out and defeat the purpose. This problem took some creativity to address. As a result of this I revised the design of the blocks.
I did two things to solve the issue. I flipped over the blocks so instead of a nice taper, there was a sharp edge. This hopefully would eliminate the tendency for the blocks to spread, at the expense of marking up the barrel. The second thing is I took a couple blots and placed them on either side and used them to “Clamp” the blocks together. It worked and I was able to press the barrel the rest of the way.
As stated in the caption when I was done pressing the barrel in the locking lugs dropped into place on the Go Gage but not on the No-Go gage. What I didn’t know was that the lugs were not. fully engaged. I would find this out later when I assembled the bolt carrier. I’ll address this issue in a separate write up.
went fairly well.
Now I was on my way to assembling the rifle.
I did a quick assembly with the parts I had at the shop to check and make sure things were going to fit together ok. The wood handguards were very tight to the receiver. I don’t know if the receiver was made a little on the large size or if the hand guards are a bit small. They did not fit the stub this tight. However the piston freely moves and the rear site lines up with the front site. All in all, this went well.
Now to address the faulty barrel blocks. We corrected the issue of the blocks spreading under pressure by using two bolts to clamp them together rather then clamping them down to the press. There are several ways to solve this, but I figure the simplest way to do it is presented below.
The most stressful part of this build is completed. Everything else should be simply firearm assembly. Now we get to find out if we truly have all the small parts needed to finish the build