How Low Will You Go?

[Old Bob]

Haven't thought to go down to 55, i would think a 55 in 6mm has a worse BC than 55 in 5.56...
how low would I go?  I guess I would look at the 75 vmax, I've done that one a few times in .243, it' a screamer.
... guess I'm assuming you have that bullet, these days you might need to shoot the ones you have in hand.
With Lever and looking at the 75 Hornady data, I'd bet I might get up close to ~3200 in my 20".  Close to ~3100 with AA2230 if I had any.

Shoot the ones I've got... you betcha!  You're right, the .224" Varamageddon 55gr tipped bullet has a BC of 0.255 while the tipped 55gr 6mm has a BC of 0.252. The bigger difference is in SD. .224" = 0.157; 6mm = 0.133. I got the 55gr bullets 'cause it's was only one of two 6mm bullets they had at Cabellas. The other was 100gr Hornady Interlock BTSPs. I got them too. It's slim pickin's for bullets around here. Primers/Powder? Forget it!

My barrel will be 20" as well. 3200/3300 fps should be in reach with the AA2230 & the 55gr bullet. I've got some 88gr Berger varmint bullets coming from Brownells. Should get around 2800 fps with Lever & that bullet.