Idea for Retumbo in 7mm SAUM. What do you think?

[JARHEAD1371]

I'm trying to find a starting point for load development for my custom 7mm SAUM. Is a slow burning powder, like Retumbo, a good choice for 168gr Bergers and a 28" barrel? If not, what do you suggest? I was also considering RL-17, but it's faster burning. Any ideas?

 

[VTi]

I spent a good deal of time experimenting with Retumbo in a longer bbl (28") 7wsm with the even heavier bullets - 180gr Berger VLD.

I arrived at the conclusion that it did not work that well. It was consistent, but I could not push the velocity to the point I was looking for (3100fps +) and still maintain a COAL of 2.860" to easily feed out of AI mags. I got to about 3000fps, no pressure signs at all, but the powder was getting way to compressed for my liking so I didn't want to go any higher with the charges.

Finally, I stepped down to H1000 and got fantastic results. I shoot several different 7wsm's and strongly believe H1000 is the single best propellant for the 7wsm and heavier bullets.

Just my opinion, YMMV of course.

 

[Long Time Long Ranger]

I have never loaded for the 7 saum but my guess is way to slow for that cartridge. Try something faster.

 

[Coyboy]

Ryan, I would think H4831sc and may-be H1000 would give good results.

 

[buckbrush]

Another vote for H-1000. 168 Bergers, 2.850" OAL, 65 gr and getting 3065 fps.

 

[VTi]

What's the barrel twist? If it's 1:9 or faster, just go straight to the 180 VLD's. I assume you're taking this rig well out past 1000yds, and the 180's ballistics are much superior at those distances.

 

[JARHEAD1371]

What's the barrel twist? If it's 1:9 or faster, just go straight to the 180 VLD's. I assume you're taking this rig well out past 1000yds, and the 180's ballistics are much superior at those distances.

It is a little faster than 1:9, something around 1:8.6 I believe. I was thinking about the 180's but I already had a new box of 168's. I plan on shooting at least out to a grand.

 

[saum7]

Been thinking the same thing , I have loaded up some 180 berger's started with 65gr of AR2225 the same as retumbo , But not had the chance to fire them yet ,
try looking at this site good write up about 7mm
7mm Cartridge Guide .
I think there is a person on this site goes by the name of Wild_Bill . Who is tring some loads with retumbo. Maybe he will see this post and reply.
try looking here Big Stuff -- 6.5mm and Up -

Cheers

 

[MontanaRifleman]

RL 17

Out of a 24 3/8ths barrel

3193 with 180 E-Tips seated to fit the mag

2935 with 210 Bergers seated to the lands

hard to beat that...

-MR