What’s up with 30-378?

[nealm66]

A busy construction friend called me up last night and asked if I would help him with one before next Wednesday. He paid for load work up and data from a local but then they had trouble with it. He wants to take it to Idaho next week. Yaay! ( not! ). Anyways, I searched for threads on the cartridge and everything looked like old posts so I figured I'd try to fish out some updated info. What's the deal with the published load data on this caliber? I remember a while back seeing a clip of mark and Sam pushing a 250 Atip at somewhere around 3150 if I remember correctly. But the I don't see any published data that gives it much speed with the heavier bullets? Did they do something to the chamber to create the additional speed? Sounds like they had finished with the 210 nosler and retumbo but I don't have the rifle or data yet. He has an old faithful 7mm mag that he's very effective with if I fail so not end of world but I'll give it a go. Just was curious what I should realistically be expecting from this cartridge or if anyone has some good advice.

 

[Dosh]

66, are you starting a new load? Are you looking for velocity or accuracy? My 30/378 Wby is most accurate at a slightly slower velocity. A week isn't much time to acquire components, work up loads and test them. With the scarcity of components perhaps the old faithful is a better choice. A 7mm Mag will kill anything in Idaho.

 

[nealm66]

66, are you starting a new load? Are you looking for velocity or accuracy? My 30/378 Wby is most accurate at a slightly slower velocity. A week isn't much time to acquire components, work up loads and test them. With the scarcity of components perhaps the old faithful is a better choice. A 7mm Mag will kill anything in Idaho.

Well, he said they were having trouble getting it to group and the cost per round and short on time made him stop. He believes a base screw has came loose and is asking me to repair and shoot for groups and verify click data. If it doesn't group then he will use his 7mm. I've only shot this cartridge once many years ago with a browning with the boss system and I was curious how much recoil I was going to be dealing with in case I need to bring a pillow for my shoulder and when I started looking at load data I was seeing slower speeds than I expected and was curious if this was accurate or if many have found speeds much higher than posted data. Seems like a lot of powder for not much results but maybe that's not correct?

 

[MagnumManiac]

Pressure does appear to rise quicker with this cartridge than velocity.
I played with one many years ago.
I think you need to use powders like H50BMG, US869 and Vhit 24N41/20N29 to get the most out of the cartridge.
I dabbled with RE33 back then but there was no data and it proved difficult to not get some pressure excursions and I left it alone in the end.
I think Kirby Allen has some recent data on similar sized cases, but the throat length may be quite different.
I have my own wildcat 338-416 Rigby Improved I always wanted to neck down to 30 cal, but always thought that the pressure would rise faster than velocity does.
The problem is the expansion ratio, the bore size is just too small for the case capacity.

Cheers.

 

[nealm66]

Thanks for the responses. I guess what got me wondering is the video with mark and Sam shooting the 250 Atip. I don't remember if I even watched the video but I thought they had it around 3150 fps which made my shoulder a little nervous. Then when I looked at the reloading data I figured I'd ask on here and see what was up

 

[Dosh]

The Wby Mark V 30/378 with factory brake recoil isn't a shoulder killer. My 12 year old grandson has shot it many times. Shot mine only once without the brake, just once!