Small base die 308 Winchester

[baconeater20]

Ok so I might be over thinking this but would there be a pressure or velocity change in a round the is FL sized using a Small Base vs A normal FL size die??

Also I am hoping to get in the 2600+ fps range with the 185 jugs in a 20" HMR. Which powder do you think I should start with, varget or IMR 4064? I am also in south Louisiana so temp stability would be nice.

 

[elf]

My guess is there would be very little - if any - difference in pressure or velocity.

Varget.

 

[baconeater20]

Figured there wouldn't be. I only have a small base set. I FL size everything so that's where the question came from.

 

[Doom2]

4064 or Varget should work equally well. 4064 is typically more available.

I think 2600+ may be optimistic with those powders. If thats important then 2000MR may be a better choice, but it will be more sensitive to temperature.

 

[cohunt]

IIRC, small base rcbs size to the same size as hornady dies--it differs between manufactures

some guys have measured the difference on a case and come up with as small as .0003" difference up to .001"-- forster claims .003" difference on the .308 sb dies

it will also depend on your brass hardness and spring back

 

[RT2506]

This is what my experience is. I do not know if it is because of the slightly tighter chamber on the rifle. I have a rifle that was built for hunter class bench rest target shooting back in the 1980s. It is a 308 Win Heart barrel 21 1/2" on a Rem 700 Short Action. The chamber is tight and is tight necked. I have to use small base dies to do any sizing of the case body and that is just a very small amount. In this rifle depending of the powder used I reach max pressure 2 to 3 grs of powder before I get to book max. I get the velocity I should get with the higher powder amount with the lower amount though. I have a 264 Win mag with a tight chamber but I can use standard dies and size the body enough but still reach max pressure with less powder but still get the velocity of more powder. So it all really comes down to YOUR particular rifle as to what happens.

 

[Canhunter35]

On a 20" tube, I think 2600fps will be just out of reach with varget but you might get there.
The real question is where it'll shoot well. My guess is around the 2500mv

 

[Hand Skills]

Best velocities I have seen with the 180's are over 2000MR powder.

 

[rsmithsr]

n140 and lapua d46 185 are over 2600 BUT A 24" BBL

 

[Canhunter35]

Best velocities I have seen with the 180's are over 2000MR powder.

Cfe223 also works for velocity.
I've wondered about vv 540n at least according to vv load data, but it's expensive so never tried it

 

[sturner]

180 gr partition
42.5 Varget
2518 FPS
Group was crap

 

[BHP9]

I only use SB dies for .308 and I'm getting 2700fps with a 175 SMK and zero pressure signs. Also excellent accuracy.

 

[Shane Lindsey]

Got to 2632 fps with the 185 HVLD in a 24" barrel. FC cases, Varget.

Primer pockets started to loosen up after two firings.

FWIW, factory Berger 200.20x loads shoot to 2475 fps in my 20" Carbon Six barrel.

 

[rsmithsr]

why USE a sb die on a spec chamber ?
your brass, your gun, no reason NONE.

I only use SB dies for .308 and I'm getting 2700fps with a 175 SMK and zero pressure signs. Also excellent accuracy.