Home Forums Hunting & Shooting Custom Rifles & Wildcats .270 barrel twist

My son is building a .270 win on a pre-64 action. He’s probably going to use a Pacnor but doesn’t know how many grooves or what twist to order. He will mainly shoot “normal’ bullets, but doesn’t want to handicap himself if he wants to shoot longer bullets later. Any words of wisdom?

Have a look at Berger’s twist rate calculator and order a twist that will fully stabilize the highest BC bullets available.

John

If he's using Pac-Nor he only has one choice, a 5 groove 1:8 twist. Every thing else is a 1:10 twist or slower.

To use the really long .270 bullets, he may need a longer throat than the standard reamer. He should decide what he wants to use (not what he may try down the road) and tailor his barrel and chamber to that.

I wasn’t aware of that Berger page. It looks very useful. Thank you.

Nice catch. Thank you

I’m really ignorant on what the number of grooves does. I need to dig into this further.

5R 1-8

There's no reason not to go with a 1-8. Normal .270 bullets are unlikely to come apart due to increased barrel twist.

I'll disagree with you on this. I recently owned a 6.5 Creedmoor with a 1-8" twist and I was unable to shoot the light Speer TNTs. With max loads they'd disintegrate in flight. At 100 yards pieces were kicking up dust on both sides of a horizontal 4 foot by 8 foot target "platform." I'd expect a .270 with a fast twist to do the same with light varmint bullets.

I'm considering picking up a .270, with the 1-10" twist, specifically to avoid the limitations with light bullets that the 6.5 PRC, which I currently shoot, imposes on me. Though there are high BC .277 bullets now, the selection is better with 6.5 mm or 7mm and I'd recommend anyone wanting to focus on fast twists and high BC for long range to go with either of them over .277. Let the .270 Winchester do what it does best .. flexiblity. 90 grain TNTs through 160 grain partitions. If someone really insists on going with fast twist in a .277 bore, do the 6.8 Westerner.

I just had a Pac Nor #2, 1:8 twist, 5R put on a rifle. Got the rifle back last week.

Have some 180gr Woodleighs, 175 NBT, and 150gr Badlands bullets to try. I would have zero hesitation running any standard 270 hunting bullets through it. I actually think the faster twist will help 130/140gr mono performance on game.

I used to run 90gr hollow point bullets out of my 270 way back when it was my only rifle. Will an 8 twist tear this bullet apart? Possibly. I will never find out as I have zero desire/need to run that type of bullet out of any of my 270's every again.

Hence why I said normal .270 bullets. I don't consider a Speer TNT a normal .270 bullet. Sure any light jacketed varmint bullet has the possibility of coming apart. Much better tools than a .270 to varmint hunt, IMHO.

It isn't so much about the bullets coming apart, it is about to throat for 175s. if you want to shoot those bullets, it may limit your options with the shorter bullets. Talk to your gunsmith about what bullets you INTEND to run and optimize for that.

1-9 is what I'd do.

Thanks for all the advice. I’ll pass it along and recommend 1 in 8.

Looking at prints the freebore of chambers designed to shoot the long, heavy .277" bullets has a freebore diameter for 0.001" and about 0.100" of freebore length, meanwhile traditional .270 chambers are freebore diameter of
0.0013" if I'm reading it right and 0.080" of length.

Might have been a 5 groove but not a 5R
Most 5R barrels are cut rifled and Pac-Nor's are button rifled

stand corrected

I have a 1-7.5 Krieger I’m looking forward to booting up to something 270 in the future. I have 0 worries about it hurting hunting bullets.

An experienced member here (I won't use his name out of respect) went down this path trying 1:8 and 1:9s and found 1:9 to be the best compromise.