Reduced load question. 375 H&H

[Batesmotel]

I’m loading Speer .375 270 GR. The Speer manual says 80 grains of IMR 4831 as a starting load and 82 grains as a Max with 82 grains being a compressed load. But even 80 grains will be a compressed load. I don’t know if I can even compress 82 grains enough to seat the bullet. I’ve never been a fan of compressed loads. 
 

I can fit about 72 grains of 4831 comfortably without compression. I can find no data on a load this light with these components. 
 

Is there a problem with a range (non-hunting) load this light. Pressure spike or over pressure possibilities?

I have always just loaded by the book. Home brew ammo is not my thing so this is new territory. But I’m not too comfortable with this much compression. The case is really full at 80 grains. Can I safely under load by 10%? I think I remember being told to never go under published starting loads. 
 

Thanks. 

[crockett]

On 8/13/2021 at 5:26 PM, Batesmotel said:

I’m loading Speer .375 270 GR. The Speer manual says 80 grains of IMR 4831 as a starting load and 82 grains as a Max with 82 grains being a compressed load. But even 80 grains will be a compressed load. I don’t know if I can even compress 82 grains enough to seat the bullet. I’ve never been a fan of compressed loads. 
 

I can fit about 72 grains of 4831 comfortably without compression. I can find no data on a load this light with these components. 
 

Is there a problem with a range (non-hunting) load this light. Pressure spike or over pressure possibilities?

I have always just loaded by the book. Home brew ammo is not my thing so this is new territory. But I’m not too comfortable with this much compression. The case is really full at 80 grains. Can I safely under load by 10%? I think I remember being told to never go under published starting loads. 
 

Thanks. 

 

 What caliber exactly?

.375 Ruger

.375 Remington Ultra Magnum

.375 Holland & Holland Magnum

 

What bullet exactly?

- Speer .375 270 gr Boat tail (Bullet Length 1.300in. / 33.02mm)

- Speer .375 270 gr Hot-Cor (Bullet Length 1.044in. / 26.52mm)

- Speer .375 270 gr Grand Slam (Bullet Length 1.250in. / 31.75mm)

 

The max difference in length is 6.5mm. That is a lot!

If you try to seat bullets with different lengths and / or base form to the same OAL, you will end up with different levels of compression, up to the point of unsafe loads.

PS: if you are going to underload, watch out for squibs. Blowing up your chamber or barrel with a larger caliber often comes with injury to hands and face.

 

[Batesmotel]

H&H

I went ahead with Speer’s published data. I found the same load in three other places including Kenn Water’s Pet Loads Vol II from 1978. Just never loaded many compressed loads but I know they are very common. 

[crockett]

11 minutes ago, Batesmotel said:

H&H

I went ahead with Speer’s published data. I found the same load in three other places including Kenn Water’s Pet Loads Vol II from 1978. Just never loaded many compressed loads but I know they are very common. 

And that's the added issue. The boat tail bullets are much longer, hence less case capacity for powder at same OAL, hence a lot of compression.

I pulled up a couple threads and others said it will be a tight fit.

[Batesmotel]

Thanks.