80 SMK, 80 VLD and 88 ELD specifically shot amazing in my Mullerworks 0.219 7 Twist. I could not get consistent accuracy out of the 90 SMK's with that MW.. And thats the bullet I wanted to shoot coming from 220TB shooting the 90 SMK @ 3000 into stupid small groups out to 1000yd for years. Id find a good load at 100, I would then get unexplained, random flyers at distance. Went through many different powders, charges, seating depth tests. I ran into this exact same problem with 22GT.
I ordered 2 Bartlein 7.5twist and had each chambered in 22BR and 22GT. Right from the start, stupid consistent accuracy. No fussing with powders, seating depths, nothing. I had all the exact same data from the MW 7 twist and you would think I was shooting 2 different calibers just going from 7 to 7.5 twist.
I want to make sure we are talking the same results/numbers here. I want to be clear here. I am not saying the MW 7 twist 22BR shot 2 MOA groups or anything unacceptable. It just wasnt shooting consistent 0.1's, 0.2's @ 100yd and 0.250moa or less at distance like my previous 220TB was. And that was the gun I was replacing when I jumped into 22BR so I wanted equal results..
I was still getting 0.5-0.75moa accuracy from the MW 7 twist.. But, I would get 3-4 shots in one hole then a flyer that would open the groups up to 0.5-0.75 consistently and with no explanation.. Thats what drove me to run my RPM numbers and go up to a 7.5 twist..
Here my 22BR 90smk results after switching to 7.5 twist. Initial testing with same everything as the MW 7 twist. I couldnt shoot a group over 3/8" and my final load shoots in the 0.1's.... You can see I have a low node at 28.7gr which is my go to nice easy load which sped up on this new barrel to just over 3000.... I have a high node there at 30.2gr which sped up to right at 3100 but thats too fast for me. My goal when I went to 22BR was 90smk right at 3000fps..
Bartlein 7.5 90smk OCW
Bartlein 7.5 90smk Seating Depth Test