300RUM to a Tomahawk?

[meatyrem]

I am wanting to know the advantages to rechambering the RUM to a Tomahawk if any? What are the nesessary requirements in doing so? What could I look to gain in performance also? I read on a other thread that the tomahawk can drive 190's at around 3600fps. Don't know if that's possible, but would like to know if anyone can lend some knowledge.

 

[Len Backus]

If you do a search here for "tomahawk" in the thread title you'll find some helpful threads.

I did some case capacity measurements 7 years ago and estimated that there is about a 4 grain difference from a 300 RUM case.

In my humbale opinion, that would result in about 100 max fps velocity gain.

You'd also get the advantage of a sharper shoulder angle which reduces case length stretching.

 

[meatyrem]

Well that was I was wanting to hear back. So in your opinion, do you think the effort and cost is worth it for about 100fps?

 

[jmden]

Probably not worth unless you have the xtra cash and just like messing with wildcats like that. The sharper shoulder angle would be nice.

Several years ago I designed, in conjunction with Dave Kiff at PTG,what I called the 300 RUMBO. I believe it was Autorotate here on lrh.com that bought the reamer and go gauge from me as I had decided to go to a 338 Lap Imp, the 338AX, specifically, instead. The 300 RUMBO absolutely maxed out the 300 RUM case, more than the Tomahawk even, but again, probably not enough to make a meaningful difference, unless you just like messing with wildcats. Autorotate built a rifle around the 300RUMBO, but his smith didn't fully get the max out of the case by not inserting the reamer are far is it should go so that a guy could still shoot a standard 300RUM case out of the rifle. So unless someone else actually fully utilizes that case capacity by building another rifle and using the reamer as it was designed, the capabilites of the design won't be known, but it won't be anything earth shattering. Autorotate was trying to sell his dies, reamer, etc. for the 300RUMBO some time ago.

 

[J300UM]

I had my 300UM rebarreled a couple years ago to a 300 Weaver (300UM W/40 degree shoulder and less taper). I was only able to achieve about 100fps over the RUM. My accuracy however came in at the same velocity as the load I had for the RUM. If I had it to do again, I would have just stayed with the RUM and eliminated the fireforming process. Buy the brass, prep it, and shoot it. The rifle is very accurate ( 1.5" @ 600yds all day) but I think my accuracy edge came from the new barrel, not the cartridge. It may not be the exact same thing as the Tomohawk but it sounds very similar so I figured I would share my experience.

 

[meatyrem]

Thanks a lot guys, that helps me make a wise decision and stay with what i've got. I just thought that I could do something with one of my two RUMS to enhance performance, but I think i'll just put that extra $$$ into better brass , powder and bullets.



Thanks anyway, I always like good info to read too. Meatyrem

 

[Long Time Long Ranger]

No way you can get 3600 fps with a 190 grain bullet with anything off the RUM case. Maybe 3450 fps with a 30-378 wby which is way bigger than a RUM. A guy has to use some common sense on the internet at times. Like when some guy got on here calling his 257 STW by some proprietary name he called it and saying over 4000 fps with a 100 grain bullet, nonsense! The 25-300 wsm I have heard called a bobcat or something and that it will shoot faster than a 257 wby, nonsense! The 338-300 RUM 100-150 fps faster than the 338 RUM, nonsense! A guy really just needs to use some common sense sometimes. The 257 STW, 25-300 wsm and 338-300 RUM are all great cartridges, but that is not the point. Point is people fudge sometimes on the results.

 

[meatyrem]

LT LR


I found that statement from an older thread at the bottom of the page under the thread tomahawk. It was posted by ( daveosok ), post #7. Witch states.......using a 34" barrel 100gr h-1000 was getting 3600fps with the Berger 190's. It does seem
a little far fetched to me also. I just wanted some clarification as to starting this thread to those numbers too. I have been reading your post's for some time now and happen to put alot of value to your facts and opinions and have learned so much from what you and others have to say here, and am gratefull. Thanks for your input, it is helpfull.

 

[Long Time Long Ranger]

I didn't know you were talking a 34" barrel. I thought we were talking normal barrel lengths. The 300 RUM is very accurate and very consistent with top velocities from what I saw on my range. So you can predict this one with fair accuracy. Looking at some of my data out of several 28" barrels they run consistent with top velocities around 3340 fps with the 190 grain bullet. With six more inches barrel length giving it 30 fps per inch makes it 3520 fps. Could improving it make it 3600 fps, maybe. Figure he could have had a hot load and a fast barrel and yes with a 34" barrel it could be possible. I guess from now on I need to ask rifle description before I answer. I always just assume a normal rig unless somebody specifies differently.

 

[meatyrem]

Not to worry, nbd. I didn't catch that at first either as to what length they were using. I also read on a similar thread of the exact same load combo and velocities. As for me, I think I can be just as satisfied with what the standard RUM load can through out.