Sherman wildcat's

I know a guy in Kamloops whos got a 338 SSM, think he is on here, I know he's on the HBC site... I don't think proper head stamp brass was very cheap or easy to get...
 
I have been interested in those cartridges for a long time. Always thought the 7mm version would be the ticket. In the end I have decided to go with the 280AI for my next build, it just seems as a SAAMI cartridge now the 280 Ackley was the better choice for me. I have the stock, bottom metal and mag parts already, waiting for the action and barrel now.
 
Yes Aron (ruby) has a 338 Sherman SHORTY and Loves it - Brno284 (Mitch) built it for him ! RJ

I sure do. Rich has a whole lineup of cartridges. Getting the most out of a saum case is his Max lineup, can even shoot factory saum rounds to fireform. The true short action cartridges is the SS and SST, based on a shortened and improved saum.

His originals is based off a 270/280 case, improved a bit better than an ackley.

The newest kid is the 30 Sherman magnum (although he did originally wildcat it 10 years ago) an improved 300 PRC that can shoot factory ammo.

Which one interests you Jim?
 
Planning to do one, have a terminus zues action coming with both a regular and magnum bolt, be able to do a switch barrel setup with some flexibility in cases. Want to replace my 338edge with a ss, I don’t mind the drop in speed of 200-250fps. Been following the shermans on LRH for s few years, I think some of the high velocities / case size that guys talk about has to be from running high pressures, but I do that in a few guns too. So why not one more?
 
Almost the same as my 270 Gibbs that Ron Propp rechambered in a Ruger No 1 many years ago. 130 gr bullets at over 3400 fps and 150s at 3200.

Rocky Gibbs was doing the same on 30-06 brass sixty years ago.

The short mag cases are new of course.

Ted

I have a friend who had Ron Propp do a 6.5 Gibbs for him many years ago, he killed a ton of moose and deer with it.
Cat
 
I owned a 30 Gibbs for a couple of years. It would drive 180 grain Partitions to 2990 fps in a 26" tube, so
basically like a factory SAUM or WSM. Killed a moose with it....worked just fine, but no advantage over my
pet chambering, the 308 Norma Mag other than cheap brass. :) Dave.
 
Here’s a 270 Gibbs all ready to go on my Ron Propp rechambered Ruger No 1.

E04D7682-0654-4FA3-965D-958B0509C525.jpg

Look familiar? Almost identical to the Sherman 270.

Ted
 

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Here’s a 270 Gibbs all ready to go on my Ron Propp rechambered Ruger No 1.

View attachment 369234

Look familiar? Almost identical to the Sherman 270.

Ted

Somewhat similar. The Sherman is based off a 270 win so it has a longer neck than the ‘06 based Gibbs. It also has a 40 degree shoulder, vs 35 in the Gibbs. Rich Sherman praises the Gibbs and ackley versions, he just made his version a bit better than either. Better is debatable of course, but his is a good design.
 
Somewhat similar. The Sherman is based off a 270 win so it has a longer neck than the ‘06 based Gibbs. It also has a 40 degree shoulder, vs 35 in the Gibbs. Rich Sherman praises the Gibbs and ackley versions, he just made his version a bit better than either. Better is debatable of course, but his is a good design.

And if you do it off 280 Rem brass, better yet. I've owned numerous Gibbs, more than a few Ackleys and a couple RCBS improveds. Individual rifle differences made more difference than the variation between all of these. FWIW - dan
 
And if you do it off 280 Rem brass, better yet. I've owned numerous Gibbs, more than a few Ackleys and a couple RCBS improveds. Individual rifle differences made more difference than the variation between all of these. FWIW - dan

I thought the 280 and 270 both had the same case lengths? Or is it another reason you figure it’s better to do it off a 280 case?
 
If a rifle is a re-chambered 270 Winchester, one can use 270 brass, without trimming, and have the longer neck. My grandfather's rifle, which is now owned by my cousin, was a FN rifle which was re-chambered by Rocky Gibbs. In this rifle, he is able to use full length 270 Winchester brass. Rocky intended to use the readily available GI 30'06 brass so designed his cartridges that way. The slight difference in length has a much greater effect in the imagination of the shooter than in actual fact.
All of these cartridges achieve very impressive performance figures only when loaded to very high pressures. I have re-chambered and tested rifles in cartridges of ascending capacity several times and got a real good look at what could be expected. Every time, the take-away was, if you want magnum performance, you want a magnum case.
 
I thought the 280 and 270 both had the same case lengths? Or is it another reason you figure it’s better to do it off a 280 case?

280 case is slightly longer to the shoulder and neck. There was also a line of cartridges based on an extended 30-06 case some years back, though the name escapes me at the moment. - dan
 
280 case is slightly longer to the shoulder and neck..... - dan

That is where the Gibbs gets its extra case capacity. The case body is blown out almost straight, and the shoulder blown ahead about a tenth of an inch, much further than the 280 Rem. The result is the very short neck seen in the picture I posted.

Having said that, the real truth about velocity is explained perfectly by Bill Leeper in his post #17 above. For me, the 270 Gibbs was simply a fun project to see what could be accomplished using cheap brass found everywhere.

Ted
 
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