Any 30-378 guys?

[EasyShooter]

Looks like I am going to be building a 30-378 from a Savage 338 Lapua. At first I was just going to buy a reamer and barrel and get to work but started wondering if I wanted the freebore of the reamer a little longer. Then if it is shooting heavier bullets what twist rate would I want? I have no experience with the 30-378 so thought it would be a good idea to see what others are doing for chamber size and barrel selection. Thanks
Ryan

 

[Carolina Hillbilly]

I have a 30-338Lapua. Much easier to find quality brass if you’re buying a reamer anyway. It’s a hammer.

 

[Gb300wm]

A 10 twist will be fine with all the heavy bullets at velocities the 30-378 is capable of...

 

[EasyShooter]

Thanks for the responses so far. I am building this gun for a buddy of mine and he is just wanting the biggest and baddest .30 cal round. I have already found lots of Hornady and Nosler brass available for 30-378 but should I look for another brand? Will probably stick with the standard .361 freebore just to keep things simple and be safe with factory ammo. Was just curious to see what others thoughts were on freebore. A 30” barrel with 1-10 twist sound okay.

 

[Ledd Slinger]

Not the best choice of cartridge in my opinion. If he doesn’t anneal the cases he might only get a few firings before splitting necks. Quality brass is extremely important with large magnum rounds. Build something that will allow you to use Lapua or ADG brass.

I’ve ran the Berger 220gr up to 3174 fps in my 300 Norma Mag Improved so far and still have no pressure signs and room in the case to go faster. My brass life with Lapua has been excellent so far.

Just about gave up on my 338-375 Ruger until I got my hands on some ADG 300 PRC brass that I was able to neck up. The Hornady brass just wouldn’t hold up when I pushed speeds. Now with ADG brass, I have renewed hope for the rifle

 

[EasyShooter]

Thanks Slinger the tips on brass. I have been using mostly Hornady brass on stuff I have been reloading. Biggest is 300 win mag though and so far have only lost one case after 4 reloads. Now I am also trying to decide on neck size for the reamer. I don’t think I want it real tight even though brass would last longer if it was. Am thinking .004-.005 range? Reloading manual shows 30-378 brass neck size is .337”. So add .004 or .005 to that and I want the reamer neck .341” or .342”. Am finding a lot of contradicting info on neck clearance on chambers.

 

[Ledd Slinger]

Thanks Slinger the tips on brass. I have been using mostly Hornady brass on stuff I have been reloading. Biggest is 300 win mag though and so far have only lost one case after 4 reloads. Now I am also trying to decide on neck size for the reamer. I don’t think I want it real tight even though brass would last longer if it was. Am thinking .004-.005 range? Reloading manual shows 30-378 brass neck size is .337”. So add .004 or .005 to that and I want the reamer neck .341” or .342”. Am finding a lot of contradicting info on neck clearance on chambers.

When building a reamer don’t go off of manuals, order the brass and bullets first. Measure the neck diameter with seated bullets in a few cases and add .004” for a no-turn chamber.

Im not sure what the seated neck diameter is on a 30-378 WBY with the brass you plan to use, but .342” should be pretty close to what you need.

JGS is the best when it comes to reamers in my opinion and they are very helpful when designing chamber dimensions. After designing the chamber finish reamer, I send my print to Whidden Gunworks to have a custom FL bushing sizer die made. This ensures I am working my brass as little as possible to prolong the life of my cases without having to constantly anneal.

For a seater die, I purchase a Wilson in-line micrometer blank (requires arbor press) and have it made with my reamer so the seater die matches my chamber. Be sure to get the VLD seater stem if you plan on shooting heavy long range high BC bullets.

If you want a threaded seater die, you can get a blank seater die from Newlon Precision.

 

[std7mag]

While 30-378 Weatherby is certainly no slouch, the Lazzeroni 7.82 Warbird would be the biggest, badest 308 caliber available.
Reload data showing a 200gr bullet at 3,358 fps.

Seems like everyone forgets Lazzeroni when looking for speed.
Not mainstream enough i guess.

 

[B23]

Maybe consider something like a 30-338 Lapua Improved. As has already been mentioned 338 Lapua brass is considerably better/tougher and will last much longer.

Defensive Edge Rifles has their 300 Terminator which is a 30-338 Lapua Improved with a 35 degree shoulder and their proprietary +P throat design.

They launch the 230's 3250fps from a 28in barrel AND they have already formed brass as well as dies on hand. They also have load data available so it makes things pretty easy peasy with one stop shopping. https://defensiveedge.net/300-terminator/

 

[LA50SHOOTER]

Looks like I am going to be building a 30-378 from a Savage 338 Lapua. At first I was just going to buy a reamer and barrel and get to work but started wondering if I wanted the freebore of the reamer a little longer. Then if it is shooting heavier bullets what twist rate would I want? I have no experience with the 30-378 so thought it would be a good idea to see what others are doing for chamber size and barrel selection. Thanks
Ryan

I have 4 barrels chambered in 30-378 and I had the reamer built off of the Norma brass that the dummy round was built & then sent to JGS for the Finish Chambering Reamer. - The design that I went with uses brass that is neck turned for a 0.3360 neck. - The throat is set for 230 gr. Berger hybrids (Not a conventional "Wheatherby" style long free-bore throat) and eventually I'm sure that I'll lengthen the throat a bit for one barrel for the 245gr. EOL Bergers & 250 gr. Hornady A-Tip.

- Regarding your Question of "but started wondering if I wanted the freebore of the reamer a little longer. " - I'd recommend that you have a look at the attached SAAMI DWG before you proceed with that decision. - The design that I'm using has a "conventional" style throat so it uses less powder than a "standard" Wheatherby throated chamber. - As some others have posted, there are probably better designs and parrent cases to choose from than Norma Brass which has a Belt on it.
- If your deturmined to pursue the 30-378 I have a reamer & gage for sale in the classifieds. - It has cut 4 chambers and you'll need to accept the fact that you'll be doing a "skim-pass" on the necks of your brass.

P.M. if you want to further discuss.

 

[EasyShooter]

Thanks for all the great advice. I can definitely see how many wouldn’t care for the 30-378 if no brass is going to last long. Will talk with the guy the gun is for to see what he wants to do. Pretty sure he is going to stick with the 30-378 though.

 

[Ledd Slinger]

We only tell you this because I’m sure everyone like myself has built or bought many custom rifles using rounds that don’t have Lapua or ADG brass available. Not such a big deal if just wanting to run loads below max pressure. But when doing a big round where you are looking for speed, good brass is SOOOOOOOO important.

The split necks are the least of the issues with lesser quality brass because the necks can be saved and last a long time by annealing them regularly. But there’s nothing you can do to save the weak primer pockets of cheaper brass. Once a primer pocket gets stretched out with high pressure loads, it doesn’t matter if the rest of the case is in absolutely perfect condition, the brass is ruined because it can’t hold a seated primer and has to be thrown away. Trust me, we’ve all been there and done that with fast rounds using all the cheaper brass. Whenever I build a rifle on a big fast round, I won’t even consider a cartridge chamber if I can’t get Lapua or ADG brass for it or at least be able to make the brass from one of the Lapua or ADG offerings. I know I can push max pressures for top speed levels with Lapua and ADG and the primer pockets are going to hold up for a long time.

 

[cuznguido]

Yep, it is hard on brass. Yep it burns lots of powder. Yep it can kick like a mule without a good brake. But build the thing. It is soooooo worth it.

 

[Murray Brook]

Never had a problem with Weatherby brass in my 30/378. Got up to 6 firings on some of them and all is still good. Proper sizing die set up is important. I use the 200 gr Nosler l.oaded to over 3200 ft/sec so it isn't a mild load.

 

[David Milisock]

Looks like I am going to be building a 30-378 from a Savage 338 Lapua. At first I was just going to buy a reamer and barrel and get to work but started wondering if I wanted the freebore of the reamer a little longer. Then if it is shooting heavier bullets what twist rate would I want? I have no experience with the 30-378 so thought it would be a good idea to see what others are doing for chamber size and barrel selection. Thanks
Ryan

Judging from what you've posted factory freebore makes sense. When I was younger I shot this cartridge quite a bit.

From my experiance if you set your dies up to your rifle, brass life is no worse then any other cartridge in the pressure class. The 358 Norma runs a bit higher pressure and I see no difference in case life between the 2 cartridges, I have some cases fired 15 times in the Norma and in the past the same with the 30 378, I haven't loaded them for quite a bit of time.

The cartridge is extremely over bore so barrel life is shorter, with slow firing rates maybe 1,000 rounds, if you regularly start popping 4 or more rounds a minute look to 500 or less for barrel life.

I stuck with the 358 Norma for my needs, the 88 grains of water case capacity was easier to live with verses the Weatherby cases at 103 grains of water in terms of total costs, powder, barrel life and shooting comfort.

The reality is that the 358 Norma in a 26" barrel with the increased diameter suited my needs better than the big 30 from Weatherby.

 

[B23]

Thanks for all the great advice. I can definitely see how many wouldn’t care for the 30-378 if no brass is going to last long. Will talk with the guy the gun is for to see what he wants to do. Pretty sure he is going to stick with the 30-378 though.

If you run it fairly moderately brass will last much longer but the whole point of going with the big 30-378 case is so you can push big heavy bullets fast and when you start standing on the 30-378, or 338-378 for that matter, to get the speed out of it is when you'll start losing primer pockets. It's not so much that Weatherby/Norma brass is shit but rather it's soft and the primer pockets are the first thing to go.

I used to have a 338-378 and loaded moderately brass would last quite a few firings but what the hell is the point of having the biggest baddest commercially available 30 or 338 cartridge if you can't stand on the gas.

The 30-338 Lapua Improved or even 30-338 Norma Improved, when using Lapua brass, IMO, are far better choices AND if you are running the gun as a repeater, those other two, compared to the 30-378 Wby are even better because the parent case is much shorter and you don't have to seat the bullet so deep in the case.

 

[El Matador]

Weatherby/Norma brass is just fine if you load to normal pressures. If you want to push your rifle beyond SAAMI pressure limits then you'll benefit from the harder Lapua brass, but I've never felt handicapped with the 378 case. I run the 338-378 and I have no issues achieving the levels of performance I want without losing primer pockets. I have 5 loadings on some of my brass and they are still plenty tight. Also, I've never seen or heard of people having neck splitting issues with these. Weatherby holds their chamber tolerances pretty tight (+.005" total neck clearance on mine) so there's minimal movement of the neck with each firing. A custom reamer would reduce the chances of neck splitting even further. The 30-338 Lapua Improved and 300 Norma Improved are also good choices but no matter what you choose there will be pros and cons.

 

[EasyShooter]

Thanks everyone for all the info and advice it is greatly appreciated! Plans are to stick with the 30/378. The gun probably won’t get shot a lot so a short barrel life shouldn’t be a problem. I have 80 rounds of once fired brass coming, should be here today. Will load up one blank round to measure the neck before I order a die. Leaning toward the standard .361” freebore and neck having .004” clearance. Used 338 Lapua Savage 112 is being shipped. He is considering not putting a muzzle brake on this gun once we rebarrel it. I think I might have him shoot the 338 Lapua gun before we take it apart. Some with and some without the brake to help decide if he wants a brake on the 30-378.

 

[davidjoe]

Looks like I am going to be building a 30-378 from a Savage 338 Lapua. At first I was just going to buy a reamer and barrel and get to work but started wondering if I wanted the freebore of the reamer a little longer. Then if it is shooting heavier bullets what twist rate would I want? I have no experience with the 30-378 so thought it would be a good idea to see what others are doing for chamber size and barrel selection. Thanks
Ryan

I read long ago that the throat starts moving measurably in this cartridge within the first box of bullets. So, maybe you don’t need to worry about that. I have a W MV 30-378 in Accumark and I believe it is a great choice because it is among the few guns that will last one’s lifetime, as will an S&W 500 Magnum and all my 50 BMG’s.

 

[Ledd Slinger]

Never had a problem with Weatherby brass in my 30/378. Got up to 6 firings on some of them and all is still good. Proper sizing die set up is important. I use the 200 gr Nosler l.oaded to over 3200 ft/sec so it isn't a mild load.

Considering I have pushed a 180gr Accubond up to 3230 fps in a 300 win mag, a load using 200gr in a 30-378 at 3200 fps is a not a hot load by any means. The 30-378 can push a 200gr much faster than that.

I have also pushed the 220gr Berger up over 3200 fps in my 300 Norma Mag Improved rifle. Still a smaller case than the 378 WBY.

Case capacities:
300 NMI, 35 deg shoulder and straightened body: 110gr H2O

30-378 Weatherby: 133gr H2O