Retumbo Charge Weight

[barnesuser28]

i have a factory savage 110 fcp hs in 338 Lapua and 85 grains of Retumbo in Lapua brass with a 280 grain Barnes Lrx at .100 off the lands is my max load.
Most people with the same rifle are saying that about 90 grains of retumbo with a 300 grain smk or a 300 grain berger otm is their max.
i am just curios as to why my max charge weight is so low? it is going 2737 out of a 26 inch tube. Any help is apreciated

 

[green 788]

what is your OAL? you're probably into the lands pretty well, which will run pressures up...

if you're anywhere above 3.700" you might be pressed against the lands... depending on your particular chamber... they're all tight on the Savage rifles...

Dan

 

[barnesuser28]

sorry the .100 meant .100 off the lands

 

[orch]

Hmmm.... Well each rifle is different I suppose... I'd expect a little more velocity outta that lighter bullet compaired to a 300gr bullet... I Guess the Barnes bullet being solid copper means it is going to have to be longer compaired to a lead core of the same weight giving it more bearing surface could be causing more friction and therefor causing u to reach peak pressure sooner....

How is accuracy? Is there much copper fouling? I know the original Barnes bullets were a little more prone to cause copper fouling... That could be causing the problem if there was a whole pile of copper constricting the bore...

Orch

 

[green 788]

ok... my bad, I didn't see that when I read your post the first time.

It's gotta be those solid copper bullets then, harder engraving force = higher pressures, but if it's shooting well, all is well...

I use the 300 grain Sierra Matchkings, and 89.3 grains is giving me just at 2700 fps... 92 grains gave me 2800 fps, but pretty flat primers and some ejector swipe... so I dropped it down to the next accuracy node, which I found at 89.3 to 89.5 grains in Lapua brass.

 

[barnesuser28]

right now they are shooting .75MOA but i am going to tweak the powder charge a little and try to get it to .5MOA or less.
copper fouling is not bad at all i put one patch of kg-12 and let it sit overnight and in the morning there wasn't any copper left.
i would think that with the bands it would reduce the bearing surface considerably. i posted some pics about a month ago here's a link http://www.longrangehunting.com/forums/f19/barnes-280-grain-lrx-pictures-90256/

 

[green 788]

bearing surface, you're right, once the bullet is engraved.

I was talking about the added pressure it takes to get the solid copper bullet into the lands, i.e. the engraving force.