.20 X 6XC or 20 X 22Middlestead

[Spook]

Seeing what was possible with the 20Brx and the Berger 55 , I got it in my head to do a Big 20 .
The 20XC would amount to a 20-250 30 degree improved and theres a Redding die that'll make it easy.
That case is probably the limit of what can be done with a 55 gr bullet ?

or

I can always convert a Middlestead die to a bushing setup and use 243 brass.

Thoughts ?

[Chickenthief]

The 204 Ruger is 34 grains of H2O
The 22-250 is roughly 44 grains of H2O
The 22-243 Middlestead is something like 56 grains.
Unless you go long tube you cant burn that extra powder, it's as simple as that.

A 204 Ruger in a 24" barrel will do @ 3300fps with that bullet for @30grains of powder.
The -250 will do @ 3550fps (a whooping +7½%) for an added 25% powder.
The big one will up that 3300fps by @10% to 3600fps for another 60% added powder (48 grains) in the same 24" barrel.

That will scortch the inside of that tube like the fields of Stalingrad in '42!

[rickiesrevenge]

The 20-250 will do more than 3550. Some guys here have seen velocities in the 3800fps neighborhood. The problems will be with keeping the 55's together.

[Chickenthief]

Remember i stated a 24" barrel and the speeds are predictions by QL.

[Timbo]

In my experience, I'm obtaining around 3700ish without pushing hard using a standard 250 case. Accuracy is very good and while I could probably get higher velocity, I'm very happy with what I've already got.
Oh, and the brl length is less than 24" by the way. Can't remember exactly how long it is but not 24".
Hope that helps.

[Tim Anderson]

I'm with Ricki you can get more than 3800 with a big case (20x47 Lapua) and also agree the bullet is the deciding factor, will it hold up at those speeds? Nope!

[trotterlg]

Since bullet rotation speed is the only thing that really matters to the bullet stability, just go with a slower twist barrel when you build a big 20. What twist it takes to make a Vartag stable is much faster than what it would take to make a 20-08 stable if you are using the same weight bullet and hitting top speed in each. I am putting together a 20-08 or a 20 Swift on an Arsaka action and will simply go with a 1 in 12 I think. The math doesn't lie. Larry

[Spook]

Thanks for the information guys, trotter , I like the way you think

[trotterlg]

I think you need to pick the barrel twist last after you figure out how fast you can shoot the bullet you choose to use. Then you calculate what spin rate you need for the bullet to be stable, then pick a barrel what will do it. This whole thing about fast twist barrels is just nuts I think, but it is a cheap way out if you don't want to do the math, only problem is that when you get to extremes with velocity that fast twist bites you with little gray poofs about 40 yards out. Larry

[BangPop]

Originally Posted by trotterlg

I think you need to pick the barrel twist last after you figure out how fast you can shoot the bullet you choose to use. Then you calculate what spin rate you need for the bullet to be stable, then pick a barrel what will do it. This whole thing about fast twist barrels is just nuts I think, but it is a cheap way out if you don't want to do the math, only problem is that when you get to extremes with velocity that fast twist bites you with little gray poofs about 40 yards out. Larry

Words of wisdom right there. Those 40 yard poofs suck.