I am getting ready to order two barrels from Lothar Walther and I noticed that L W has US system spec and European spec. barrels.

US spec. 404 Jeffery is .411 land dia. & .423 groove dia. with 1:14" twist & the 9.3x62 has .354 land dia. & .366 grove dia. with 1:12 twist.

C.I.P. spec 404 Jeffery is .412 land dia. & .424 groove dia. with 1:16.5" & the 9.3x62 has .354 land dia. & .365 groove dia. with 14.2" twist.

I not trying to start another great twist rate debate.

But what would the advantage or disadvantage of a 404 with 1:14" or 1:16.5" and a 9.3 with 1:12" or 1:14.2" twist.

Will be using 300 to 400 grain bullets in the 404 and 200 to 286 grain bullets in the 9.3x62. Both jacketed and cast.

I will guess most here will say go with the faster US spec. twist and I really don't have a problem going with the faster twist.

But I'm wondering why there two different "standard" twist rates and slight differences in bore and groove dia.?

What would be the advantage of one over the other be, in these two calibers in particular?

Allen

This is probably not what your looking for BUT. Palma Barrels (.308 WIN) are usually .3065" groove and .298" bore. They shoot great and no signs of excess pressure. If it were me, I go with the tighter specs. As for twist rate, I realy don't know. My .404 has a 14" twist from PAC-NOR and it shoots good groups with Woodleigh and A-Square bullets.

My 9.3 are 1:14 IIRC

My two L-W barrels are .423. They shoot great! If you are building a 404 Jeffery then you should use .423. Just my opine!