20BR/20-220 Swift education

[trotterlg]

Sort of what I found with the 760, I think that part of the success with the Varget is that it is one of the "extreme" line. They add a little Nitroglycerine to up the energy content some. I think the pressure curve is more to the liking of the real oversize cases. I am going to keep moving up with it, I still have about 2gr more case capacity. Larry

[410gauge]

Larry, got back out today with the 20WSSM. Thought I finally had something going...but alas not so. Got the velocity up to 3840 fps with the 55 gr Berger (no poofs)...but ended up sticking a case so tight I'll have to pull the barrel. Have decided I've played enough with this case. I'm going to cut the barrel back (plenty of shank) and re-chamber to a more mundane case. Almost 12 grs more powder to achieve 190fps increase in velocity is just not worth it I've decided. It has been a interesting challenge. Onward. 410gauge

[trotterlg]

I think the 20 Swift is a little more than the practical limit of a 20. I am still getting increases in velocity with light bullets. Could be that the heavy bullets just puts the pressure curve in a bad place. I haven't had any sticky cases, but the Swift does have quite a bit of taper so it is likely harder to stick one in the chamber. Next week I will run it up a little more and we will see. Larry

[GrocMax]

Pretty sure Varget is single base, at least the MSDS doesn't indicate any nitroglycerine or nitroguanadine.

[Alycidon]

My theory is to fill the case with the coolest powder you can that will give you the velocity you desire. I use N150 in 20BR, most would say its to cool but I get 3500 with 50s and .2 accuracy, low ES, whats not to like.

A

[trotterlg]

I agree, my 20BR gets 4,250 or so with a full case of 4064, I have some loaded in my 20 Swift now, just haven't shot it yet. Larry