Re: New .22 Cal Matchking
Ian, Thanks for posting the details of the 90 grain Matchking.
I am delighted that Sierra has introduced this bullet, as it underpins a project that I have commenced, but can understand the sentiments of others who would have preferred something different.
Now with the 90 grain grain JLK ULD, and 90 grain Sierra MatchKing, together with Richard Graves 85 grain ULD, and possibly 90 and 100 grain FBHP's, wildcatters and target shooter's have enough bullet variety to build a rifle with a 6.5 or 7 twist.
I am planning to build another 224 Clark, but this time on a Rem 700 long action. I estimate that I should get 3500 - 3550 fps with the 90 grain bullets, based on the 3730 fps I achieved with the Sierra 80 grain HPBT in my last 224 Clark.
The rpms with the 90 grain are interesting with 2700 fps (estimated 223 velocity) producing 299,076 rpm in a 6.5 twist, and 324,000 rpm in a 6.0 twist.
3,200 fps is producing 329,142rpm in a 7 twist, and 354,461 rpm in a 6.5 twist, and 3,500 fps in a 7 twist is producing 360,000 rpm, and 387,692 rpm in a 6.5 twist.
I don't know how long the 90 grain Sierra is, but you would tend to believe that a 7 twist producing 360,000 rpm should produce adequate stability. Also, I have spoken to several who successfully used the 90 grain JLK with a 7 twist. The Sierra 69 and 80 grain HPBT Matchking's have proven that their jackets are tough, and after looking at the above figures the 90 grain will have to be as well.
However, I remember Dave Corbin's (bullet die manufacturer) comments to me that he had made numerous die sets for the 85 - 90 grain bullet weights, and he recommended using 257 calibre jackets drawn down to .224 in a jacket reducing die. His experience was that these bullets were tough enough to withstand the combination of high velocities and fast twists, and worked quite well. As always time will tell. Brian.