Home Forums Hunting & Shooting Custom Rifles & Wildcats 6mm Weatherby RPM 3600fps, 115gr Berger (pic)

Could be. I'll try it on another conventional chrono as well as the Labradar.....if it will read it.
Quick Load predicted 3400fps, but it called out a bunch of powders that proved to be too fast burning.

Tony

That sounds a lot more in line. Interesting cartridge anyway, would be neat if there were some stoutly built 6mm heavy bullets to better handle the Big 6s.

Has there been any pressure measurements ?

Of course not. It's not slated for production by any means. There will most likely only be one made. Mine.

If you guys would like to just tell me how fast it should go, I will reduce the load accordingly, post those numbers for you, and everyone will be one little happy family.

Tony

You're the guy coming on here making wild velocity claims. This isn't 1960, we have the collective knowledge and software to pretty much predict right where a cartridge will perform, even if you choose to ignore it.

Your wrong about alot of things.
But your right about that..

dave

Sounds good. So how fast should it be going?

Quick Load already predicted powders that were too fast for the cartridge with charge weights that were way too high. If I used QL data, the primers would be falling out of the cases. Those loads were way over pressure before I even got close to the max suggested by QL.

I'm open to learning from you experts here. If you have a powder recommendation and or charge weight to try, let me know. I probably have it. Here's a pic of some that I have on hand....there's another wall full as well.

Tony

P.S. For whatever reason the 108 ELD-M's run way higher pressure and less velocity than the heavier Bergers. I'm sure you guys can tell me why.

I ran up two more powders tonight with the Berger 115. Shooters World SW50BMG and Reloder 50. Both petered out at about 3400-3450fps.

That's about all the powders available in this burn range area. I'm going to go back and retest 24N41. As much as I like to spar with you guys, the pressure is probably a bit high for any kind of decent case life at 3600fps, but I'll see with more testing. I have a feeling it will probably settle out at about 3450-3500fps without trashing cases. Then I'll machine a new barrel and test accuracy. I don't buy pre-fits wobbling around in a CNC chuck with a floating chamber reamer wobbling along with it.

Tony

Edited to add: I'll have some once fired brass for sale shortly. lol

Wow that's a fair selection of powder.
Have you measured your 6 RPM's case capacity?

Hal

Thought about a 25 rpm once. But this could be a fun one. Liking it.
I'd think you'd want to use some 4831 to get some case fill on that puppy. Maybe?

Have you given any thought to Hammer bullets?
dave

What about RL33, LRT or N570? Those three have been killers when I need a slow powder for Ultra Mags and similar.

What's the COAL in the 1st pic for the 6RPM?

Why would he handicap this cartridge with those?

In Quickload, are you adjusting the Ba Value in the Propellant Table Setup? There you'll be able to have it output the slowest burning available powders. Also, Quickload seems to often show higher charge weight estimates than reality, but the velocity estimates are generally closer to the ballpark. For those who might not be all that familiar with the program, it's really more for general estimates than actual load data, much as the disclaimer when one opens the program denotes!

As far as estimating velocity ahead of time, using "Barsness' Rules" to compare off of established pressure tested data for cartridges with similar capacity, bore diameters, and bullets will come up with a pretty close estimate on expected speed. In this example I'd probably compare it to pressure tested 6.5 RPM data, a larger 6 with tested Berger 115 grain loads, and perhaps published 257 Weatherby 115 grain data. Come at it from a few different angles and compare that with Quickload's estimates for the custom round design and you might even be on the basepath.

This stuff is all possible to figure out before firing a round, and really should be done beforehand to establish safety guardrails and minimize expense and time spent chasing one's own tail.

I'm not around my copies of JB's Gun Gack books where the The Rules are published, so will quote a post from RockyRaab about the subject:

I went ahead and backed all the loads down to 2900fps, so everyone should feel all better now.

Tony

What's the COAL of the pictured 6RPM/115 Berger?

Has anyone done a 6mm-7prc yet?

Tony

Thanks for sharing the information you have accumulated. I always learn something reading about the experiments of others.

This site is populated by some “gentlemen” who look for something to criticize.

West Texas Ordinance has data for a 25/7PRC.