What upper receivers are you guys using to get a good thermal fit?

[flogxal]

What I question now is how tight can a thermal fit be before it should be considered too tight. That was the problem I had with at least one of the BCM uppers that I got. It was so tight that I couldn't true the receiver with neither of two tools. When I went to fit the barrel to one particular upper, I had a time getting it in.

I have a BCM upper that I used for Proof 18" SS in 6 ARC. Proof had a recall on the extensions, I got mine back from Proof and I swear the new extension is bigger diameter. The upper + barrel are sitting in my basement as a project, last time I tried seating the barrel I got halfway in and it stuck on me. Trying to heat the throat to tap it free, still stuck. Same throat fit the prior extension pretty damned snug but still, it didn't stick on me halfway in.

 

[WeR0206]

I have a BCM upper that I used for Proof 18" SS in 6 ARC. Proof had a recall on the extensions, I got mine back from Proof and I swear the new extension is bigger diameter. The upper + barrel are sitting in my basement as a project, last time I tried seating the barrel I got halfway in and it stuck on me. Trying to heat the throat to tap it free, still stuck. Same throat fit the prior extension pretty damned snug but still, it didn't stick on me halfway in.

This is what I use to remove a stuck barrel:

• Wheeler Upper Vice Block (# 156888) ($32) (to secure the upper)
• 1”x12” Wooden Dial Rod ($10)
• 16oz Rubber Mallet ($12)
• Wagner 1200W Heat Gun (# HT1000) ($24) (use on high for about 60-90 seconds)

This video demonstrates it:

 

[flogxal]

That's exactly the process I used (JP video) with wooden dowel and a dead blow hammer. I wish I had taken calipers to the extensions, old and new, but didn't.

Most likely I didn't get it warm enough -- but I'm using the same propane tank & torch as used on a handful of other BCM thermofits.

 

[TonyAngel]

I have a BCM upper that I used for Proof 18" SS in 6 ARC. Proof had a recall on the extensions, I got mine back from Proof and I swear the new extension is bigger diameter. The upper + barrel are sitting in my basement as a project, last time I tried seating the barrel I got halfway in and it stuck on me. Trying to heat the throat to tap it free, still stuck. Same throat fit the prior extension pretty damned snug but still, it didn't stick on me halfway in.

This is what I use to remove a stuck barrel:

• Wheeler Upper Vice Block (# 156888) ($32) (to secure the upper)
• 1”x12” Wooden Dial Rod ($10)
• 16oz Rubber Mallet ($12)
• Wagner 1200W Heat Gun (# HT1000) ($24) (use on high for about 60-90 seconds)

This video demonstrates it:

Yeah, been there. For me, the wooden bowl or rod or whatever you want to call it just resulted in a bunch of wood debris all over the place. I also wasn't crazy about using an upper fixture that would have put most of the force into the pivot pin and/or take down pin lug. I happened to have a pretty beefy optic riser from leupold that I dont use. It has both recoil lugs and 5 screws for the clamp that are spec'd to 60 in-lbs each, so I attached that to the rail on the upper, flipped it upside down and clamped the riser into my vice. I then used a brass rod after applying a good bit of heat. I did get things apart.

Just out of curiosity, I wondered if it was a problem with the machining of the upper or perhaps the anodizing was just too thick. I had this little tool that is not unlike the tool used to hone the cylinder walls on an engine and used it to see if I could open the upper up a bit, without destroying the anodizing. I was able to improve the fit a good bit and was able to get the truing tool into the upper after that, but at that point, I didn't have any confidence in the upper due to how hot I had to get it to get the barrel out. I trashed it after the little experiment.

 

[WeR0206]

Yeah, been there. For me, the wooden bowl or rod or whatever you want to call it just resulted in a bunch of wood debris all over the place. I also wasn't crazy about using an upper fixture that would have put most of the force into the pivot pin and/or take down pin lug. I happened to have a pretty beefy optic riser from leupold that I dont use. It has both recoil lugs and 5 screws for the clamp that are spec'd to 60 in-lbs each, so I attached that to the rail on the upper, flipped it upside down and clamped the riser into my vice. I then used a brass rod after applying a good bit of heat. I did get things apart.

Just out of curiosity, I wondered if it was a problem with the machining of the upper or perhaps the anodizing was just too thick. I had this little tool that is not unlike the tool used to hone the cylinder walls on an engine and used it to see if I could open the upper up a bit, without destroying the anodizing. I was able to improve the fit a good bit and was able to get the truing tool into the upper after that, but at that point, I didn't have any confidence in the upper due to how hot I had to get it to get the barrel out. I trashed it after the little experiment.

Good point about not putting too much stress on the pivot pin holes. If there was a barrel that was really stuck in there I also have the JP upper vice blocks that secure it via the pic rail.