|Originally Posted By rjay:|
In looking at the m261 it is obvious that you save a ton of work by using this kit as the basis for the 22mag conversion. The ejector is simple to cut back and the lower part of the bolt will be simple to modify to work with the longer cartridge. With your pushrod idea the only thing 'difficult' will be chucking the bolt up in a 4 jaw lathe chuck and opening up the bolt face.
What did you use for a buffer spring ? My 22mag upper will probably end up on a Cavalry Arms polymer lower with the carbine buffer and spring.
You have discovered why I went for the M261 unit for the 22 magnum setup. It's all there -- it just needs to be adjusted to work with a longer cartridge.
I started out using a lower with the full length buffer tube. In the full length tube I used a carbine spring (no plastic spacer in there) and a carbine buffer that had the weight modified. I changed the weight around on the buffer till I got the setup to cycle and still see a normal case head on the fired cartridge. This setup does not like any movement of the weight in the buffer
so when you're adjusting the weight be sure the platic buffer tip compresses it all nice and tight each time. I started out using one of the original buffer weights and some Daisy BB's to play with the weight. If I needed a spacer to take up empty space, I used a piece of wooden dowel. In my carbine I use the same weight buffer and just cut a carbine spring back some. I can weigh my buffers and measure my springs if you want but there will be some operating differences between my setup and yours since I did my own barrels by relining them. The Redman liners are known to be tighter than a normal 22lr bore and you've actually gone to the larger .224 bore. You may not need as much weight as me but always start heavy and work back from there. When you first start, load single rounds and test -- if you have a mag in place and the cartridge case goes kaboom the magazine will get screwed. You can always test the full cycle after you get the setup firing ok. Do not forget to wear safety glasses.
The ramp on the under side of the bolt will need to be played with depending on the magazine setup you will use. There is a step in that ramp and that was for holding the bolt open when using 22lr rounds. The rear metal block needs to be cut back to allow the bolt to move back further and again, may be different than mine depending on the magazine setup you use.
This 22 magnum uppers work great -- when you get your's started, be sure to take pics and post them!