Home Forums Hunting & Shooting Gunsmithing twist rate for 300 weatherby

I'm getting ready to put together a custom build in 300 Weatherby Magnum. What is the recommended twist rate for a custom barrel in 300 Weatherby??? It will be chambered with NO freebore and I plan to shoot 180-200 grain bullets. Remington offers the 300 Win & 300 RUM with a in 1-10 twist and the 300 Weatherby in a 1-12. Anyone know why?? Thanks, 163bc

I don't know why Rem does that.............

I've had a custom 300 win with 1-12" twist and it did well with both 180's & 200's, tho I designed it with 165's as the primary weight.

To be on the safe side, I'd go with 1-10" twist; it'll handle the lighter bullets just fine & be more certain to handle the heavier ones as well.

MM

for 180's and up use a 1-10

I have had two and have one now. My current one is 1-12 and it has shot anything I have tried- the heaviest being the 180 Sierra Pro-hunter. 1-10 is overkill and will work on the really long stuff like the 210 Berger and 220 SMK. If you are ordering a custom barrel, a good compromise that will still let you get some velocity is a 1-11 twist. Contrary to what rumors you may have heard, the twist does make a difference in velocity. We built about 5 of them at once- some with 1-12 and some with 1-10. I get about 100 fps more out of the 1-12 twist barrels than the 1-10s. Lazzaroni builds his race rifles with minimal twist for this reason.

Overkill?

I had a 1/11 twist Lilja 3 groove barrel put on a 300Wby it had no wby freebore also headspace on the shoulders. Same gunsmith just finished a 257Wby same spec.

Got that same barrel on a 300mag and 30-06 he makes a great 30 cal barrel.

Why no Freebore?

If you don't, you should be leery of firing Weatherby brand factory loads, and also be leery of the top loads in loading manuals if the test rifle was a Weatherby.

Well you cann't fire factory ammo barrel is so marked as to reloading you normally use less powder to get same velocity.

I already have 1 custom in 300 Weatherby. I load all my own so I see no need for the freebore. I get the velocity plenty high without it. I'm leanin hard towards 1-10. Thanks to all for the feedback it is appreciated. Thanks, 163bc

"to reloading you normally use less powder to get same velocity."

I would want a second opinion on that. Pressure rise and velocity rise is not at the same proportion for the amount of powder added or removed.

I got lost on that one too...I've seen pressure problems from changing 'lots' of powder,once on a change in primers. Every rifle is a fingerprint..they might look the same,but they are DIFFERENT.....rifle

There is no guarantee that you will get the same velocity with "no free-bore". I know if I shoot factory ammo in my short throated rifle, I get too much velocity and pressures are higher than Norma's already optomistic level.

OVERKILL- would you call 1:6 twist overkill?? If you are trying to stretch the velocity, and this is the main reason for a 300 WBY, why handicap yourself with excessive twist. A 1:12 will do almost anything- certainly any hunting bullet that I have tried (don't know about the 200 grain Accubond- never used it) A 1:11 would certainly do anything shy of a 240 SMK.

As an update- Joel Pendergraph shot a new world's record 10-shot heavy gun group yesterday in NC of just a smidge over 3" at 1000yds. I quote his comments:

There you have it- a 12 twist with 187 target bullets. The caliber is 300 Ackley - very similar to the 300 WBY

Those were flatbases.

They were indeed!

The Palmas seem to thrive on 1 in 12,....and yes, I know that they're not pedal to metal for Vels or Bullet weights ( 155s IIRC)

slower twist dittos,

.....You'll get longer barrel life, too.

GTC

Eliminating freebore in these baby anti aircraft calibers does indeed give equal (claimed) vels. for less powder.

It also tightens up and takes all the baginess outta' your S.D.'s.

Makes 'em more accurate, so to speak.

Second opinion rendered.

GTC

"equal (claimed) vels. for less powder."

But only at the cost of higher pressures.