Forming 375 Ruger brass from 8x68s cases

[Pdvdh]

True. I left primers out because a primer gets spent during either of the methods discussed for forming the case to the chamber. I don't get serious about load development until the case has formed to the chamber. So it's C-O-W for me.

Besides that, I get old and outdated primers for free from a relative that owns a gun shop. Some customers move out of Alaska and bring their old reloading supplies to his shop rather than transporting them out of State. Customers die and their spouses bring in the miscellaneous reloading supplies. They can't be sold in the shop. These old primers are free and completely suitable for shooting C-O-W.

 

[LeddSlinger]

I like the COW because it creates the 99% complete case volume without the extra powder and a wasted bullet sent down the bore. After the COW firing, the case sidewalls and shoulder are fully formed, I can load bullets and proceed with normal load development. The same as with any new casing in any factory cartridge.

Also, I've figure out how to minimize the case length shrinkage with the C-O-W, so no negatives. Advantages are 20gr shotgun powder instead of 75-80gr rifle powder, C-O-W instead of a bullet, less erosion of the throat in order to fully form the case to the point of formal load development.

Yeah I use the COW method on some cases I form. Works really well. Well enough to use the formed cases for serious load testing. Been doing it for ages. Usually do it on my rifles where a high volume of cases is required, like varmint and target rifle wildcats. For my 338-375 hunting rifle, 50 cases will last me a handful of years. Hunting rifles usually just form 25 cases, then I form the rest of the cases over time as the rifle requires fouling shots on a clean barrel. The formed fouled cases all go in a 'single fired' pile for use when the others wear out.

 

[yorke-1]

Rich,
I'll be re-barreling soon. Is there any reason why your 30/375 S.I. Reamer couldn't be run 0.025" deeper, setting the shoulder length 0.025" longer?
AND then name it 30/375 S.H.I.?

H. for Horwath, of course!

Then run them with +50fps MV while utilizing the full length of the 8x68S casings.

This was actually my intention with the 270 Boondoggle reamer that I have. I had the reamer made so that 375 Ruger brass would work or the shortened 8x68 case. I'm going to have two test barrels cut and run the reamer .060" deeper in one to use the full length of the 8x68 case. I'll figure out which one works better and then go with it. I intended for the round to work from a 3.600" mag box though so the extra case length wouldn't offer much benefit since the bullet will be taking up a lot of the extra capacity.

For fireforming, I've used the COW method a lot with other wildcats with good results. For these cases though I'm going with an unconventional approach. I'm fireforming with spare bullets and Trailboss powder. Using Trailboss means I don't have to mess with filler material like COW or toilet paper. I just load the cases up with enough powder to fill the case to the base of whatever bullet I have on hand and go shoot it.

That's a 277gr MTAC on the right and a early version of the 307gr Hammer Hunter on the left. The MTACs shot like crap in both my 338/408s and the 307 Hammer Hunters won't stabilize in a 1-9" twist barrel no matter how fast it launch them. It's fun watching them tumble into the target though at 1800 fps! LOL

 

[Pdvdh]

This was actually my intention with the 270 Boondoggle reamer that I have. I had the reamer made so that 375 Ruger brass would work or the shortened 8x68 case. I'm going to have two test barrels cut and run the reamer .060" deeper in one to use the full length of the 8x68 case. I'll figure out which one works better and then go with it. I intended for the round to work from a 3.600" mag box though so the extra case length wouldn't offer much benefit since the bullet will be taking up a lot of the extra capacity.

Neat.
My mag box is 4.2" long, so I have no cartridge length limitation. Figure I shouldn't waste the 8x68s case capacity.

 

[elkaholic]

Neat.
My mag box is 4.2" long, so I have no cartridge length limitation. Figure I shouldn't waste the 8x68s case capacity.

If you SHERMANIZE that case clear to the current neck /shoulder junction, you should be around 100 grs or more.

 

[Pdvdh]

If you SHERMANIZE that case clear to the current neck /shoulder junction, you should be around 100 grs or more.

Just about right!
Any estimate on the resultant MV increase using the 200-225gr bullets?

 

[yorke-1]

Neat.
My mag box is 4.2" long, so I have no cartridge length limitation. Figure I shouldn't waste the 8x68s case capacity.

I wanted to have it function through one of the Curtis Custom 3 round magazines, but I may end up going with a BDL style bottom metal with a Wyatts extended box just to have the extra length.

If you SHERMANIZE that case clear to the current neck /shoulder junction, you should be around 100 grs or more.

I thought about using the extra length of the 8x68 case to give a nice long neck for the 170 Berger and 168 Hammer Hunters in the 270 and just give a longer neck to the 338.

 

[elkaholic]

Just about right!
Any estimate on the resultant MV increase using the 200-225gr bullets?

I would have to see a print or maybe check out a case tomorrow to estimate capacity more accurately. Does anyone have a print? Velocity would depend on how much throat we put in it. I have a trick throater we could use too!
You should pick up at least 50' though, and likely more.

 

[yorke-1]

Chamber dimensions from QuickDesign

 

[elkaholic]

Thanks Yorke!
Paul....you could run my reamer in about .060" and gain about 3 grs it looks like. You would be at about 99 grains. You would need dang near 2.8" mag to shoot the 225 ELDM because coal to the lands would be around 3.76". Now that I look at it a little closer, I think you would be lucky to gain 50'.
Sure would make a nice 338 though!

 

[Pdvdh]

Thanks Rich.
Yes, I calculated 3.2gr additional water capacity if I ran your reamer in an extra 0.070", which might be the max with the 8x68s case.

For comparison, my ballistics program shows the 300 Win Mag at 87gr, the 300 Weatherby at 97gr,, and the 300RUM at 110gr water capacity. And you believe the fully Shermanized 30/8x68s would yield ~99gr water capacity. That seems like a good balance in case capacity for performance versus throat life. Halfway between the Win Mag and the RUM.

You meant 3.8" mag length, correct?

 

[elkaholic]

Thanks Rich.
Yes, I calculated 3.2gr additional water capacity if I ran your reamer in an extra 0.070", which might be the max with the 8x68s case.

For comparison, my ballistics program shows the 300 Win Mag at 87gr, the 300 Weatherby at 97gr,, and the 300RUM at 110gr water capacity. And you believe the fully Shermanized 30/8x68s would yield ~99gr water capacity. That seems like a good balance in case capacity for performance versus throat life. Halfway between the Win Mag and the RUM.

You meant 3.8" mag length, correct?

Yes, 3.8"

 

[gregsjt]

Is there not another case that has a .532 rim and head? Is the 375 Ruger and the 8x68 the only cases that are close without going to a belted case?

 

[elkaholic]

Is there not another case that has a .532 rim and head? Is the 375 Ruger and the 8x68 the only cases that are close without going to a belted case?

Nothing else that would work