I once had a SS Tikka CTR 6.5 CM With a 24 inch barrel that I work up a load for that ran 2700-2725 fps. Really great shooting gun and a really consistent shooting load. I traded it off. I have traded for the same gun but with a 20 inch barrel. My question is how much speed loss do you think I’ll have? I know the rule is 25-30 fps per inch. And I know I’ll have to work up another load but just wanting to see want everybody’s experience is.

Ammo Bullet weight (gr) Bullet G1BC G7BC "Powder - IMR 4451" Muzzle Velocity (feet/sec) Test Barrel (inches) Velocity - Adj to 20" barrel
Trophy Gold" 130 Berger Hunting VLD 0.562 0.236 2784 22 2634
Hornady SP 129 Hornady SST 0.485 2930 24 2630
Handload 123 Hornady A-max 0.51 42.8 gr 2612
Handload 123 Hornady A-max 0.51 2780
Handload 135 Berger Classic Hunter 0.584 42 2563
Handload 143 Hornady ELD-X 0.623 0.314 41 2577

This is what I'm getting with a Tikka T3CTR in Rem 260. We saw 300fps drop in from 24"to 20". It is closer to 50-70fps drop......

I believe the 6.5CM loses less than the traditional rule of thumb. I've heard the 20" only shoots 50-75 fps slower than the 24" in the Tikka.

My CTR 20” is shooting a 143 ELDX and H4350 at 2700.

I need to chrono my 24” again with Chad’s ammo. It was 2790 but I think it has sped up some; I’m close to 200 rounds down the pipe now. The last two times I shot it the corrections suggested it’s faster now.

147 ELDM's @ 2700 is not problem with RL26 and a 20" tube.