i have 2 22-243 standard shoulder one has a 1x9 twist and the other a 1x8 they wont stablize in the 1x9 and about 1 out of 3 come apart in the 1x8 twist so i have not had much luck with them 75 grn A-maxes seem to work the best for me along with some imr7828
Hi i did a review on the 90gr Sierra's and got a brand new 6.8 twist barrel and chambered it in 223 it was extreemly accurate and the elevation of a 5 shot group was .320 high at 300 yards and the wind got me so it opened to .865 wide 4 touching and the other 1 out to the left. then i rechambered the barrel to 22-250AI with everything else the same and could not get the 90's to stay togethor i used powder as slow ar H50BMY right to H4350 and every one in between to try and change the engraving pressure. once they go much past 3000fps that is the end of them. i have also tried them in a 30" 8 twist and at 300 yards they also shot very well. i think the upper limit for them is a 22BR. the other thing the 75gr A Max'x blew up in the 6.8 twist barrel when it was a 223.
Hi i have had extensive discussions with Rich Machholtz at Sierra as the testing i conducted was for an article here in the Australian Target Rifle Magazine. The 90's are the best long range projectile you could get for a fast twist 223 or 22BR but their have been issues with them holding togethor when pushed fast. That being said Rich was having luck with them in a 8 or 9 twist 22-6mmAI so their is a lot of horsepower there and they were going faster than 3200fps. i susp[ect that if a true polygonal barrel with 6 or more groves and lands with the minimal twist required to stabalise them they would work but that is to much of a gamble. i shot the 55gr BlitzKings through this barrel 65gr SPBT GAmeKings, 69, 80, and 90gr MatchKings through this barrel aswell as the Hornady 75gr A MAx and 75gr HPBT the only failures in 223 were the 75gr A MAx and the only failures in 22-250AI were again the 75gr A MAx's and the 90ge Sierra's. The 69 and 80gr Sierra's were awsome performers in the faster twist and all projectiles that were consistant (did not blow up) shot well under MOA to 300 yards and the match projectiles stayed under MOA to 1000 yards ( except the 69gr MatchKings they died in the 223 at 700 yards). As a 223 i shot 5 shot groups at 1000 yards with the 90's un sorted or measured and had 4 shots into 1" elevation with 1 shot opening the elevation to around 4" and the windage was 7.9" for 5 shots. 4 were under 4" wide. so this is exceptional shooting for a 223 and un marked shots with 5 shot groups not 3 as i believe a true indication is at least 5 shots.
Anyone looking to build a 22BR or 223 i would not hesitate to advise them to get a 7.5 or faster twist 30" barrel and shoot the 90gr Sierra's at 1000 yards they are slightly better in windage and elevation than a Sierra 155gr Palma MAtchKing leaving the muzzle at 2930fps.
The load i was using in a very long throated 223 with the boattail junction above the doghnut in the case was.
Rem 7 1/2 Benchrest Primers
90gr Sierra MAtchKing 20 thou into the lands.
The MV was 2860fps in a 30" barrel
Do not load this start at 22gr and work up looking for signs of pressure these are safe in the chambers we cut with a long throat but not a short throat.
The articles are with the publishers at the moment awaiting publication.