Rear sight base stuck on Contender barrell

[curioushooter]

So I bought another used Contender barrel. This was the first that wouldn't lock up on my G2. Did the usual judicous honing of the locking lugs with the assistance of a magic marker and a properly locking barrell as a guide, and a half hour later it all works great. Then I go to try to remove the rear sight base. Wanted to put preferred set of sights on and may want to mount red dot in future...well...the sight base is stuck on. Looks like loctite. I hope it is not epoxy. While the screws came right out, the base will not come off. I have it soaking in Acetone right now. Anyone observe this or have any guidance? Did the factory solder these on? Or is there another screw somehow concealed?

[country gent]

I have seen them locktited on and epoxied on the heavier recoiling barrels. I have seen one that was soldered on also. If Locktite or epoxy it shouldn't take to much heat to break it loose. Most locktites and epoxies break down around 400*. So a heat gun or propane torch played on the sight base not the barrel should break it loose. Another way is to place the barrel in the freezer for a couple days. before warming it. the expansion from cold to hot breaks the bond

[William Yanda]

Yep. Heat is the cure for loctite.

[curioushooter]

I tried a light touch with a torch already. Afraid of messing up the heat treatment these barrels have. But I may just be paranoid. The chamber beneath the screw holes is about the weakest part. It's a 357 Herrett barrel, so not particularly powerful, so I am a bit surprised by this. Will try freeze then heat.

[country gent]

Look at some of the early Herret data that was published and it was a lot warmer then. My Herret barrel sheared the screws of on a burris rail mount once. Some of the 180 grn and 200 grn data was fairly heavy recoil

[curioushooter]

Yes the old data was a bit too hot IMO. But, there is no need to solder those bases on. Just a bad idea. I ended up grinding it off with a belt sander after chickening out with a torch. Finished it off with a file. Too much work. (https://guidetograssandguns.wordpress.com/2018/03/03/bad-ideas-laborious-solutions/) Would have sent it back if it were not for the fact it is the first barrel of a bottleneck chambering I've come across with something approaching a decent throat. It is close to being concentric, straight, and groove diameter. The rifling is also way forward so there's potential with 200 plus grainers.

[curioushooter]

Regarding data. Much of the old data is so hot that you can't fit the bullet in if you want some neck-shank engagement. 28 grains of imr-4198 or aa1680 is my personal max. Still gets a 180 going 1800 plus.