Originally Posted by
shutinlead
I have a couple rifles I'm building around the GM 1:24 twist (WS502436ST) in 50-90 and the twist has been more than adequate for the 625g Baco or JIM512625C mold. I've pushed a 795g pill from a NEI mold with no issues except for what's felt on the other end. For a 1000 yds with the 625g I've found there is a preference for a little harder lead, 16:1 tightened my group size a little but it may have been the shooter and his mind set too. I shot quite a bit using the 515 in my first few times out. At 200 yards it looked to be a good candidate but when I went to 800 yards I was having better results with my 45's - not what I hoped for going to the Big 50. This first one is built around a '74 and I my intention is to be my mile gun, so far this is showing promise to 1400 yards as time and weather hasn't let me shoot it beyond that - that 400 more yards is significant.
The 28 twist should be a good fit for the 600 plus and if GM had cut their barrels in that - I'd went there without any concerns. Good luck and post your findings.
Greg