Retumbo for .243/6SLR?

[Erud]

Hi,
With the new(ish) trend of using slow-burning powders like H1000 for cartridges like 6CM and 6SLR, has anyone tried Retumbo? According to my burn rate list, it looks like it's almost the same rate as H1000, just a hair slower. I've got a couple of lbs on hand from a project that never developed so I'd like to use it of possible.

Looking for starting loads shooting 115 hbn Dtac's. Rifle is a 6SLR with 30" barrel.

Thanks in advance for any help,
Erik

 

[Dgd6mm]

I've shot it in a .243 with a 105 Amax out to 600 yards and it performed well. I also used it to fireform my 6CM brass with a 105 Amax out to 850 and it hammered. Not sure about the 6SLR with a 115 but I'm sure others have tried, someone will speak up. Have you done a search for the info?

 

[Erud]

Thanks Donald. I have searched but haven't found much directly relating to Retumbo. Any starting loads guys are using would be great.

Thanks,
Erik

 

[Erud]

Anybody? ???

 

[kyreloader]

On Dan Newberry's Optimal Charge Weight website, he shows OCW loads with Retumbo and 105/107 bullets. He likes that powder a lot in .243 Win with those bullets. Here is a link to his website with some known OCW charges.

http://optimalchargeweight.embarqspace.com/#/ocw-load-recipes/4533485759

(I realized you asked about 115s, but I thought this may be a starting point).

 

[Erud]

On Dan Newberry's Optimal Charge Weight website, he shows OCW loads with Retumbo and 105/107 bullets. He likes that powder a lot in .243 Win with those bullets. Here is a link to his website with some known OCW charges.

http://optimalchargeweight.embarqspace.com/#/ocw-load-recipes/4533485759

(I realized you asked about 115s, but I thought this may be a starting point).

Hey, thanks for that. That is an interesting website and one I hadn't seen before. It does indeed give me ideas on where to start with the 115's Much appreciated!

Erik

 

[Dgd6mm]

Erik, if you choose to use Retumbo over H-1000 your B.E. will be lower buy about 2% and your speed will be about 75 fps slower. I dropped the h2o 1 grain from a .243 case per what Robert says case capacity is and ran Q.L. I know this is not real world but should help. If you would like to pm your contact info to me we could talk and run some numbers over the phone.

 

[xdeano]

Erik,

I just ran a test yesterday with the H1000, i maxed out on capacity at around 47.2g, with no cratering or ejector marks, the primers were starting to flatten out a bit but no
flow back into the firing pin hole. I was only able to get 2962 out of my max load with a 105g Berger Hunting VLD. I might try the 4831sc to see if i can't get a little bit more
out of it. I'm only running a 24" barrel and my temps here were 19F.

So with the slower burning powders you'll sacrifice some of the velocity. My goal was in that 3100fps range. With 4831sc I think it is doable, but not with the H1000 due to case
capacity.

xdeano

 

[Dgd6mm]

This is true.

 

[Erud]

Well, I got it out today. Did not have much time to do any loading so I just threw 2 loads together quickly and put 30 rounds through it after our winter league shoot. 115 DTAC with 46.0 grains of Retumbo resulted in 2920 fps out of my 30" 7.5 twist Bartlein. I found half a can H4831sc so I tried RCW's recommended load of 43.5 grains and it came in right at 3000. Maybe I should just stick in that neighborhood, Robert obviously knows his stuff and I hate extended load development! Didn't really get to do any serious testing for accuracy, but I will next time.

One thing I noticed:

The Winchester brass I have is a little too tight for the 115 DTAC's I have. Neck OD measures .270" and fired brass measures .274". I picked up a .272" bushing on my way home, but will have to figure out a way to expand the necks a little and then size them back down to .272". As it is now, the necks will scrape the jackets pretty deeply, and I can't see how that can help. Brass is fully prepped; trimmed, chamfered, deburred, so it is smooth, but it's still tighter than I'd like. ES's were higher than I expected and I am sure this is a factor.

Any ideas on this? I have a .260 die that I could neck it up with, but don't know if I'll be greatly reducing my brass life....

Thanks,
Erik