30-378 Weatherby Load Data or Re-barrel to 375-338 Lapua AI? Or something else?

Paladin300

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Hey ladies and gentlemen! Just picked up a Sako M995 TRG-S in 30-378 to have my smith build a 375/338 AI on.😃 Trouble is never owned a 30-378 so I thought I‘d play with it before I disassembled it. This gun is strictly a long range gun. Specifically building a gun to play with shooting to the 2 mile mark (3520 yards+). We are shooting 6.5CM, 300WM and 338 RUM to 1250+ on a regular basis on silhouettes and have shot the RUM to 2000. Just wanting to see how far we can push the envelope with standard magnum cartridges without stepping up to a cheytac length action and I love all things Sako. Anyway here is my three part question. 1) Does anyone have any pet long range loads for 30-378 and what kind of performance are you getting out of that cartridge with what bullet. Shooting 215 and 220 Bergers in my 300WM. 2) Has anyone fooled around with the 375/338 AI and if so what kind of performance are you getting from it with what barrel length and profile? 3) Is there some other cartridge I should be looking at to build on this platform for this purpose?
 

Rifleman97

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Hey ladies and gentlemen! Just picked up a Sako M995 TRG-S in 30-378 to have my smith build a 375/338 AI on.😃 Trouble is never owned a 30-378 so I thought I‘d play with it before I disassembled it. This gun is strictly a long range gun. Specifically building a gun to play with shooting to the 2 mile mark (3520 yards+). We are shooting 6.5CM, 300WM and 338 RUM to 1250+ on a regular basis on silhouettes and have shot the RUM to 2000. Just wanting to see how far we can push the envelope with standard magnum cartridges without stepping up to a cheytac length action and I love all things Sako. Anyway here is my three part question. 1) Does anyone have any pet long range loads for 30-378 and what kind of performance are you getting out of that cartridge with what bullet. Shooting 215 and 220 Bergers in my 300WM. 2) Has anyone fooled around with the 375/338 AI and if so what kind of performance are you getting from it with what barrel length and profile? 3) Is there some other cartridge I should be looking at to build on this platform for this purpose?
All I know about the 30-378 is that it loves the slowest burning powders you can find. I know a guy that shoots one, and I asked him for some info on it when I considered buying a 30-378. He ended up talking me out of it. However, he said the 2 best results he had was with Retumbo and US 869. Downside with 869 is the terrible temp stability, but if you usually shoot with the same temps (like for me, most all my shooting is done between 20 and 40 degrees) then it’s not such a big deal.

But, since you have it... I suggest you try the 250gr A Tips. Those are the bullets that made me consider a 30-378 in the first place. Crazy velocity from 30-378, really high BC bullets, and with good lot consistency from the way they’re packaged.

So if you decide to shoot the 30-378, try the 250’s and let us know how it works for ELR! I haven’t found anyone that’s posted about that combo yet, and I feel like it could be killer.
 

yobuck

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east central fl. /n.c. pa.
I used a 30x378 for about 30 years for Pa long range hunting.
Back in the day it was as good as it gets for that type hunting.
As the barrels go, pretty much every body today is rebarreling to a 338.
My barrel was 36” and i used the old WW2 surplus H570 powder which gave the best performance.
113 gr would get 3500 fps with a 200 gr SMK. It took about 1600 yds for a 240 SMK to catch up with the 200.
At 1600 yds a large 338 becomes a better choice regardless of what bullet you use in the 30 cal.
My son has a 338x378 Wby. built on a Sako 995 action with a 9 twist 30” barrel.
The 338x378 is pretty popular among Pa long range hunters.
He cant quite get to 3000 fps with 300 gr bullets however.
For that reason quite a few L/R hunters there are using 250 gr bullets, and the same rule applies as with the 30x378.
You will be nearing a mile before the added BC of the 300 gr overcomes the velocity gain of the 250 gr.
In all my years hunting L/R in PA, i only know of one man whoes word i trust to kill a buck at one mile there.
And he did that with a 338x378 using a 250 gr bullet.
 

4xforfun

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It's been a while since I loaded for the big 30, and it was before RL33...maybe even before Retumbo. I think we were using RL25 and H1000 at the time. Now I would START with Retumbo and RL33.
 

Paladin300

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All I know about the 30-378 is that it loves the slowest burning powders you can find. I know a guy that shoots one, and I asked him for some info on it when I considered buying a 30-378. He ended up talking me out of it. However, he said the 2 best results he had was with Retumbo and US 869. Downside with 869 is the terrible temp stability, but if you usually shoot with the same temps (like for me, most all my shooting is done between 20 and 40 degrees) then it’s not such a big deal.

But, since you have it... I suggest you try the 250gr A Tips. Those are the bullets that made me consider a 30-378 in the first place. Crazy velocity from 30-378, really high BC bullets, and with good lot consistency from the way they’re packaged.

So if you decide to shoot the 30-378, try the 250’s and let us know how it works for ELR! I haven’t found anyone that’s posted about that combo yet, and I feel like it could be killer.
I would love to try the 250 A-tips but the problem I think we will run into is the twist rate in 30 cal Sako barrels. Both my 300WM and the 30-378 have 1/11 twist. That is standard for Sako. I think the A-tips were designed with 1/8 twist in mind. The heaviest I have been able to shoot in my 300WM are the 220gr Bergers but I get the best results with the 215s. They will group 1/2 moa out to at least 1250 I know and stay supersonic to just past a mile.
 

Paladin300

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Messages
194
Location
Alabama
I used a 30x378 for about 30 years for Pa long range hunting.
Back in the day it was as good as it gets for that type hunting.
As the barrels go, pretty much every body today is rebarreling to a 338.
My barrel was 36” and i used the old WW2 surplus H570 powder which gave the best performance.
113 gr would get 3500 fps with a 200 gr SMK. It took about 1600 yds for a 240 SMK to catch up with the 200.
At 1600 yds a large 338 becomes a better choice regardless of what bullet you use in the 30 cal.
My son has a 338x378 Wby. built on a Sako 995 action with a 9 twist 30” barrel.
The 338x378 is pretty popular among Pa long range hunters.
He cant quite get to 3000 fps with 300 gr bullets however.
For that reason quite a few L/R hunters there are using 250 gr bullets, and the same rule applies as with the 30x378.
You will be nearing a mile before the added BC of the 300 gr overcomes the velocity gain of the 250 gr.
In all my years hunting L/R in PA, i only know of one man whoes word i trust to kill a buck at one mile there.
And he did that with a 338x378 using a 250 gr bullet
I have a 338 custom built RUM that we are shooting 285 ELDs and 300 OTMs out of and getting between 2775 and 2820 fps with R23 and H1000. We are supersonic to 2100 yards with both loads and bullets. Really liking the 285 over 88.5 grs or R23 with a 3.950 COAL .05 off the lands. It has SDs in the low single digits but not getting any where near 3000 fps. That is pretty impressive from the 338/378. As for the 30/378 I have it has a 1/11 twist. I think I am going to be limited to 225 grain bullets or less. The 200 smks would work leaning toward the 215 otm Bergers since I already have them. I have R23, H1000, R25, R15, W760, IMR 4350, and H4350 on hand. Wondering how R23 would work?
 

Paladin300

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Joined
Aug 24, 2020
Messages
194
Location
Alabama
I used a 30x378 for about 30 years for Pa long range hunting.
Back in the day it was as good as it gets for that type hunting.
As the barrels go, pretty much every body today is rebarreling to a 338.
My barrel was 36” and i used the old WW2 surplus H570 powder which gave the best performance.
113 gr would get 3500 fps with a 200 gr SMK. It took about 1600 yds for a 240 SMK to catch up with the 200.
At 1600 yds a large 338 becomes a better choice regardless of what bullet you use in the 30 cal.
My son has a 338x378 Wby. built on a Sako 995 action with a 9 twist 30” barrel.
The 338x378 is pretty popular among Pa long range hunters.
He cant quite get to 3000 fps with 300 gr bullets however.
For that reason quite a few L/R hunters there are using 250 gr bullets, and the same rule applies as with the 30x378.
You will be nearing a mile before the added BC of the 300 gr overcomes the velocity gain of the 250 gr.
In all my years hunting L/R in PA, i only know of one man whoes word i trust to kill a buck at one mile there.
And he did that with a 338x378 using a 250 gr bullet
I have a 338 custom built RUM that we are shooting 285 ELDs and 300 OTMs out of and getting between 2775 and 2820 fps with R23 and H1000. We are supersonic to 2100 yards with both loads and bullets. Really liking the 285 over 88.5 grs or R23 with a 3.950 COAL .05 off the lands. It has SDs in the low single digits but not getting any where near 3000 fps. That is pretty impressive from the 338/378. As for the 30/378 I have it has a 1/11 twist. I think I am going to be limited to 225 grain bullets or less. The 200 smks would work leaning toward the 215 otm Bergers since I already have them. I have R23, H1000, R25, R15, W760, IMR 4350, and H4350 on hand. Wondering how R23 would work
It's been a while since I loaded for the big 30, and it was before RL33...maybe even before Retumbo. I think we were using RL25 and H1000 at the time. Now I would START with Retumbo and RL33.
I have R25 and H1000 on hand. Haven't been able to get my hands on Retumbo in a while. Do you remember what your loads were for R25?
 

yobuck

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Messages
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Location
east central fl. /n.c. pa.
Well forget all the data you read as to how far they stay supersonic for choosing a cartridge.
Go sit on a sidehill looking across a wide valley at another sidehill and watch them being shot.
There will be lots of days when none of them are any good, and there will be days when the better ones are simply just that, better.
And all of them hold lots of powder and shoot heavy bullets.
And the ones holding even more powder will always win.
The 995 Sako works ok for the 338s to a point, but id be talking to a good gun builder about where that point ends.
If i were going to keep it as a lighter gun, then id just shoot it as it is with what ever works.
 

Paladin300

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LRH Team Member
Joined
Aug 24, 2020
Messages
194
Location
Alabama
Well forget all the data you read as to how far they stay supersonic for choosing a cartridge.
Go sit on a sidehill looking across a wide valley at another sidehill and watch them being shot.
There will be lots of days when none of them are any good, and there will be days when the better ones are simply just that, better.
And all of them hold lots of powder and shoot heavy bullets.
And the ones holding even more powder will always win.
The 995 Sako works ok for the 338s to a point, but id be talking to a good gun builder about where that point ends.
If i were going to keep it as a lighter gun, then id just shoot it as it is with what ever works.
As I mentioned in my original post. I bought this gun based on my smith’s recommendation as the Sako is the only factory action that will support the 375/338 Improved platform with little to no work except a simple re-barrel. Going to drop it in a KRG whiskey 3 chassis and re-barrel with a bartlein barrel. Not sure what twist, length or profile yet. Both the smiths I use are backed up right now and it looks like it will be after the first of the year before we can start on the project. Was just going to play with the 30/378 till then and see if I liked it. One of my smiths is trying to talk me into a 28 nosier. I agree with you the heavier bullets do better and stay stable through the transonic layer. Imho, anything 220gr or heavier seems to do just fine. The heavier the less spin drift affects it as well, hence the choice of the 375/338 AI.
 
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