7mm Mashburn Super Magnum

[BobT]

Looking forward to your report of the barrel. 1-8 Mashburn should be excellent. Bet if it was released as a new cartridge today it'd be as popular as many of the other "super" mags!

Art Mashburn was ahead of his time I think. There was another version of the 7mm Mashburn on the full length H&H case but the powders of the day weren't slow enough to take advantage of the extra capacity. IIRC H4831 was the slowest burning stuff they had back then. One of these days I would like to find an original Mashburn rifle I could afford.

 

[SJB358]

Well, I took the Mashburn out yesterday, just wanted to run a few rounds through it to see how well the 160 AB, 75.5 grains of H1000, CCI 250 and reformed HDY cases are holding up...

Pretty happy with it..





Feel like I am ready to stretch it out a little...

 

[muleman]

Scotty,
You should do something about those bullets flying sideways! :grin: Seriously; that's some good performance. How fast are they moving?

Scott

 

[SJB358]

Right at 3210FPS the last time I checked them over the chrono Scott.

This is just about my least expensive rifle and it's working on becoming my easiest shooter!

Dangest things about rifles.... Just when you think you know something...

 

[JD338]

Looking good Scotty.

JD338

 

[DrMike]

Definitely cutting the target like you would want it to do. Almost bragging size.

 

[gerry]

That would have put a smile on Bob Hagel's face, looks like you have yourself a great load.

 

[SJB358]

That would have put a smile on Bob Hagel's face, looks like you have yourself a great load.

I hope so, I have been wanting a Mashburn since I was about 14... Took a couple of years to make it happen..

 

[JD338]

Another elk hammer in your battery Scotty.

JD338

 

[nvbroncrider]

Man Scotty so how many rounds are you going on this year? Or should I ask how many bullets are you going to load?

 

[SJB358]

Man Scotty so how many rounds are you going on this year? Or should I ask how many bullets are you going to load?

Ummmm, I am pleading the 5th.... :lol:

 

[Hegland]

Awesome work, Scotty! Is that a 6x42 on top?

 

[SJB358]

Awesome work, Scotty! Is that a 6x42 on top?

It is. I like it a ton!

 

[SJB358]

I did a little work with the 7mm Mashburn yesterday with the 175 PT. I tried some H1000 and Retumbo. My beginning load with Retumbo was already on the warmish side, and the group looked just about the same as the H1000 loads.

74.5 Retumbo





This was 73 grains of H1000



74 grains of H1000



Here are the speeds recorded for H1000




So, seeing all of that, which direction would you go. I plan on dropping back a .5 grain with H1000 and shortening up the COAL about .010 then reshooting. I have PLENTY of speed for what I am looking for. I am perfectly happy with anything around 3050, so I am thinking dropping back should get me in that range and maybe shortening them up a little will pull the 3rd shot in.

What do you all say?

I'd try some more Retumbo, but I am just about out, so I am going to keep on with H1000 and see where I can get..

 

[DrMike]

You are correct that there isn't much difference between the two powders. Probably not a bad idea to scale back the charge with the H1000, as you recommend. As you well know and have already speculated, altering the OAL is likely the key to improving accuracy at this point. The group that was charged with Retumbo is comforting, however. One has to like that.

 

[IdahoCTD]

You might try R-33 too if you have some Scotty.

 

[SJB358]

I don't have any 33. Wished I did but I skipped it and bought H1000.

I'm betting it would be pretty serious with the 175's.

 

[Hegland]

I'm pretty impressed with how tight the speeds are for any of those loads. They sure look like they want to shoot! They're up against a tall order to hang with those 160 ABs though...

 

[IdahoCTD]

I don't have any 33. Wished I did but I skipped it and bought H1000.

I'm betting it would be pretty serious with the 175's.

If you were around I'd donate a pound. I have about 12-13lbs of it.

 

[longrangehunter]

Scotty, I think you should play around with the seating depth as Mike said. Don't worry about which powder, but use the one with the lowest ES SD and move in small .005" amounts off the lands.