What's up with this???

[Beruisis]

I have what appears to be an unfired Kleinguenther (Voere) K15 rifle in 257 Weatherby Magnum. Barrel twist 1/12. So I buy some Weatherby 100gr Barnes TTSX factory ammo & head to the range with a chrony. Factory ammo states 3570 fps at the muzzle. This velocity usually assumes a 26" barrel.
My barrel is 25"; first two shots are 3633 & 3636 fps & 3/4" apart so I'm feeling pretty good since this is first time I ever fired this rifle & scope is just a 2.5 - 8 x 33 mm. Third shot is a surprise as it is an 1" higher than the rest & velocity reads 3733 fps.
All this is faster than advertised with a 1" shorter barrel. But even if we assume a 24" barrel from the factory that is quite a disparity in velocity from factory ammo methinks.
Has anyone else experienced this or can account for it?
Thanks.

 

[ab_bentley]

I have what appears to be an unfired Kleinguenther (Voere) K15 rifle in 257 Weatherby Magnum.

This is the answer.

Adam

 

[Beruisis]

This is the answer.

Adam

Thanks Adam, that certainly clears things up for me.

 

[ab_bentley]

Thanks Adam, that certainly clears things up for me.

It's a brand new barrel, factory to boot. The first 10-50rds are merely paving over the pot holes. Expect weird variations until it's smooths out.

Even new custom barrels have a seasoning period.

 

[JDMock]

I have what appears to be an unfired Kleinguenther (Voere) K15 rifle in 257 Weatherby Magnum. Barrel twist 1/12. So I buy some Weatherby 100gr Barnes TTSX factory ammo & head to the range with a chrony. Factory ammo states 3570 fps at the muzzle. This velocity usually assumes a 26" barrel.
My barrel is 25"; first two shots are 3633 & 3636 fps & 3/4" apart so I'm feeling pretty good since this is first time I ever fired this rifle & scope is just a 2.5 - 8 x 33 mm. Third shot is a surprise as it is an 1" higher than the rest & velocity reads 3733 fps.
All this is faster than advertised with a 1" shorter barrel. But even if we assume a 24" barrel from the factory that is quite a disparity in velocity from factory ammo methinks.
Has anyone else experienced this or can account for it?
Thanks.

Try it over another chronograph or check your chronograph with a known load's velocity. James

 

[slm9s]

Be very careful firing Weatherby factory ammo in non-Weatherby rifles. The ammo is manufactured assuming the barrel will have the Wby freebore. If the barrel does not, unsafe high pressures may result.

 

[Beruisis]

Be very careful firing Weatherby factory ammo in non-Weatherby rifles. The ammo is manufactured assuming the barrel will have the Wby freebore. If the barrel does not, unsafe high pressures may result.

Primers didn't indicate excessive pressure & extraction was easy.