30-378 chamber specs needed.

[Norz]

I´m about to start cutting a 30-378 chamber in my barrel. I´ve been hesitating for a while, but time has come to get this project started. It will have 32-34 inches of usable bore and 1/8 turns per inch, 1,5" dia.

Does anyone here have information and or knowledge on 30-378 that could be helpful to me before cutting it? Are there variations of 30-378 that are being used, if so...pros and cons?

I would really appreciate any help on this matter.

Thanks.

 

[Wild_Bill]

What will the rifle be used for? if it is hunting where you will be using factory ammunition go with a SAAMI spec long freebore reamer. If you are looking to handload for it and use match Projectiles i would look at getting a reamer made up with a 35-40 degree shoulder like a conventional case that will not allow a facttry round to chamber and a tight match throat and chamber. Call Dave Kiff at pacific Precision also talk to Kirby if he has a 300 Allen cartrige based on the 338 Lapua case improved it would be realy worth a look the other option would be a 300 Ultra MAg improved or standard. I take it the barrel is a 1 in 8 twist barrel? if so you would be well served to use 240gr MAtchKings or Richards Wildcat projectiles in Canada. I think he will be making projectiles up to 300gr if this is what you want to use i would get the projectiles and have the reamer made to suit.

Will the rifle be used as a single shot or a repeter?

What action will you be using?

Cheers Bill
Australia

 

[Norz]

The rifle will be used for target shooting, hopefully at longer ranges than my 300 ultramag. I´m looking to get to 2000 meters or more this time. Feeling quite optimystic here. The 30-378 just seems to be the only 30 cal cartridge that I know of that can I can drive hard enough to achieve my goal. Didnt look any further tough, but will do now.

Yes, 1/8 twist.

The action is my own design with 5 set interrupted threads (15 total). Single shot. Whole rifle weighs in at 22 lbs, 43 inches long.

Why 30-45 degree shoulder instead of the double radius one on the original?

 

[Wild_Bill]

Hi Norz the reason i would go with the 35-40 degree shoulder is to make sure a factory cartrige can not be fed into the chamber. i would go 40 degree in the shoulder and improve the case to 6 thounands on an inch per inch of case sidewall. The minimum is 4 thou per inch. What is the tennon size? You may be able to chamber it for a case based on the 408 case. Kirby is working on a versian in 30 cal at the moment give him an email and i am sure he would be able to help you out. I would go that way as the 30-378 brass is made by Norma and is fairly soft if you ryn them to hard you will end up killing the cases in 1 or 2 shots. What projectiles were you looking at using in the barrel?

The minimum tennin for the 408 Chey Tac case is 1.125" but if you can make it larget that is better.
The case head is .635" the same as the Rim Diameter. Could you fit it into your action?

If so this case would be the best for you to look at.

Cheers Bill
Australia

 

[Wild_Bill]

Hi i forgot to add if the barrel tennin is large enough you could machine the rims doen 45 thou to Lapua/378WBY diameter and have rebated rims as long as the action will handle the pressure. I do not believe the 30-378 will get you to 2000m the Chey Tac case would definately be a better option. another option if the Chey TAc case will not work is the 30/416Rigby improved it will give you a larger capacity that the standard 30-378 as the 378 case was based of the Rigby case when it was designed. Brass is available from a few more manufacturers aswell as not having the belt.

Cheers Bill
Australia

 

[Norz]

The action can accommodate a larger body than the 30-378. It can also handle 6 times that pressure (cad predicted though). The barrel is a full blank at the moment, started making the first run into it this morning. There is no bolt face cut yet as it is being hardened now, so there is still room for drastic changes.

I´m in northern Europe, so I would prefer using Lapua or Norma brass to avoid the export fees and regulations in the states. Is 416 Rigby brass available from either of them?

The Chey/Tac and 416 are starting to sound like better options /ubbthreads/images/graemlins/confused.gif

What is ruining the standard 30-378 cases so quickly compared to my 300 ultramag?

 

[screech]

people over working them. to much pressure would be my guess.

 

[James H]

[ QUOTE ]
What is ruining the standard 30-378 cases so quickly compared to my 300 ultramag?

[/ QUOTE ]
As WildBill said the brass is soft.
Were I you I would go with a 300/338 Lapua Imp.
Much better brass available for it, Lapua.

 

[Chawlston]

I have a 30/338 Lapua improved and I am having it rechambered to 30-378. Based on my testing of the 30/338 improved, I believe that I can better it with the 30-378. And, components are much easier to come by. I will let you know how it turns out.

James

 

[James H]

Re: 30-338 LM Imp.

Chawlston
I am curious what performance you were getting with the 30-338 LM Imp. and with what barrel length.
My 30-378 is the only gun I own that I can't load close to published max. charge wts. before I get a sticky bolt, loose primers and extractor marks. That is why I belive the brass is soft, which is why I thought the 30-338LM would be better. I am interested in how it turns out after the rechamber.
Thanks

James

 

[Chawlston]

Re: 30-338 LM Imp.

[ QUOTE ]
Chawlston
I am curious what performance you were getting with the 30-338 LM Imp. and with what barrel length.
My 30-378 is the only gun I own that I can't load close to published max. charge wts. before I get a sticky bolt, loose primers and extractor marks. That is why I belive the brass is soft, which is why I thought the 30-338LM would be better. I am interested in how it turns out after the rechamber.
Thanks

James

[/ QUOTE ]

Hello,

I was getting between 3200 and 3300 fps with the 200gr Nosler accubond. This was out of a 32" Kreiger barrel. These are roughly the same velocities that I got out of a standard 30/338 Lapua (27" barrel) that did not have the improved shoulder. These velocities were shot over an oehler 35P with the four foot spacing on the sky screens.

FWIW, I use Hall Express actions exclusively and when I told Alan Hall what I wanted, he tried to help me by steering me toward the 30/378 but I did not listen. The gunsmith who chambers a lot of my barrels told me the exact same thing and I ignored him and continued with the 30/338 Lapua improved. I suspect that I wasted close to $500 trying to re-invent the wheel.

Now, I have followed their advice and had the 32" Kreiger barrel shortened to 31" and rechambered to 30/378 Weatherby. I am anxious to see what happens.

I decided to go ahead and try the 30/378 Weatherby since the 338/378 one I have works so well with a 29" barrel. It gets 3011 fps with zero brass issues. I may regret getting the 30 caiber barrel rechambered, but if it does not work out, I still have all my options available. I do have a 30/338 Improved reamer I am going to sell if the Weatherby test is concluded successfully.

Note, I do not intend to shoot the 200 gr accubonds with this setup. I am waiting on the 290 and 265 grain Wildcats to utilize the Weatherby case capacity. If those don't work, I will be trying some 240 SMKs. If all that does not bear fruit, I will shift to the 210 Bergers and SMKs.

And, I would be interested in the results you or anybody else gets with any testing using the 338 Lapua Case.

Additionally, I get 3240 with the 225 Accubond in my standard 338 Lapua in a 27" barrel and that basically overshadows the 30 caliber results. I truly wish to find the combination to have an extreme 30 caliber shooting stick.

James

 

[Chawlston]

Re: 30-338 LM Imp.

Shot some 265s out of the 32" Kreiger 30/378 and it looks as though the barrel likes the velocity at 3040-3050 the velocity was very consistent with all loads in that range being under 10fps deviation. It works well at that pressure level but at 3100fps, the bolt lift got sticky. The slowest powder I used was N170. I am sure I could get a few more FPS out of some slower powder, but I don't think it would be more than 30-40 fps and definately not worth the expense nd hassle of ordering another keg of powder..... Will be shooting some trajectories tomorrow if the weather cooperates.

James