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7-375 ruger or 7 lrm ????

 
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  #8  
Old 01-18-2012, 02:32 PM
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Re: 7-375 ruger or 7 lrm ????

Rich,
Thanks a bunch. I read about your 30 375 si... Version. You got something really nice going there and have put slot of thought into everything. I would definitely like to know how everything is going now and once you get all your parts finished in feb.
Does anyone know if gunwerx will sell their brass or will we have to make our own. From what I understand I will need a ground down 375 die first and bump the shoulder back a little. Then go down to 338 in a shorter die like a 338 rcm or a ground down 338 ultra? Then neck to 30 with something shorter and finally size with a 7 mm neck and trim. Could I shoot then or should I finish from 30 with my 7 lrm die or what ever I make it?
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  #9  
Old 01-18-2012, 02:34 PM
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Re: 7-375 ruger or 7 lrm ????

Would the 338 rcm and 30 rcm dies be best since they are exact diameters for the body of the case to give case wall support?
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Old 01-18-2012, 04:21 PM
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Re: 7-375 ruger or 7 lrm ????

Quote:
Originally Posted by joshiwa220 View Post
Rich,
Thanks a bunch. I read about your 30 375 si... Version. You got something really nice going there and have put slot of thought into everything. I would definitely like to know how everything is going now and once you get all your parts finished in feb.
Does anyone know if gunwerx will sell their brass or will we have to make our own. From what I understand I will need a ground down 375 die first and bump the shoulder back a little. Then go down to 338 in a shorter die like a 338 rcm or a ground down 338 ultra? Then neck to 30 with something shorter and finally size with a 7 mm neck and trim. Could I shoot then or should I finish from 30 with my 7 lrm die or what ever I make it?
Gunwerks will only sell their brass to people who buy rifles from them. Once I get my rifle chambered I will get the sizing thing perfected but here is what I've done so far.
I cut .080" off of a full length 375 Ruger die and bumped the shoulder back. Next, I ran it thru a .338 RCM die set to neck size and make sure I only go back to the new shoulder, (same 30 degree angle). I then ran it thru a 300 SAUM die set to neck size and leave a little false shoulder on the .338 neck; just a few thou. This will be my headspacing angle. If I had my 30/375 S.I. dies, I might try skipping the 300 saum step and try to form the 40 degree shoulder at that time, but I really don't think that will be the best approach. My best guess is that the best approach will be to not use the S.I. die and simply fireform after using the SAUM. The case will need a little forming anyway to blow the taper out of the case body so I think this will work just fine. Basically, most of the forming will be just blowing .006" taper out and changing the 30 to a 40 degree shoulder at this point. It sounds a little tedious, but really wasn't bad at all when I tried it. With the throating in this chamber, the round should duplicate the Dakota at half the brass cost..........Rich
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Old 01-18-2012, 04:31 PM
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Re: 7-375 ruger or 7 lrm ????

Is there a reason you use the 300 saum die to neck size to .30 cal or is just because you have that die and it will fit to get the neck size down.
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Old 01-18-2012, 04:55 PM
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Re: 7-375 ruger or 7 lrm ????

Quote:
Originally Posted by joshiwa220 View Post
Is there a reason you use the 300 saum die to neck size to .30 cal or is just because you have that die and it will fit to get the neck size down.
Ya, that's what I had so I used it! Once I get my S.I. dies, I will use them instead and can either do the same thing as I did with the SAUM or try to form the shoulder to 40 degrees at the same time. I'll just have to try it and see which is best.......Rich
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Old 03-04-2013, 10:54 PM
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Re: 7-375 ruger or 7 lrm ????

Will gunwerks sell the brass to anyone now, or is it still specifically for customers only?
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  #14  
Old 03-05-2013, 06:46 AM
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Re: 7-375 ruger or 7 lrm ????

joshiwa220,

I made a necked down 375 Ruger without any other changes. The neck IS short but it works.

Talked to Dave Kiff about not moving shoulder. He said several guys did it when the 375 first came out and they had no issues with the short neck.

I wanted to do this with dies I had on hand and not buy custom dies till I knew it would shoot.
Besides having a hornady 338 RCM dieset I have a Whidden custom FL/bushing die and seater for the 338 RCM. The 375 shares the same shoulder angle and diameter as the RCM.

Here is how I did it.

Procedure for necking down 375 Ruger

1) Hornady 338 RCM FL die
2) 300 RUM FL die to taper mouth of case
3) Whidden 338 RCM bushing die with .329 bushing
4) Whidden 338 RCM bushing die with .312 bushing
5) Open up with K and N mandrel, neck turn to .013” neck wall thickness
6) Run brass into Whidden 338 RCM bushing die using .311 bushing

Ordered a 7mm/375 reamer with .317" neck

Two weeks ago I rechambered a 23 1/4" rem takeoff that was a 7 rem mag. Years ago I had that takeoff put on a Mark X and the barrel shank had to be cut off to rethread for the larger mauser shank, that is why it is so short.

Here are the details on the load development:

Seating 168 berger classic hybrid to max OAL to fit magazine of MARK X has a bullet jump of .054”

moly coated 168 Berger classic hybrid and H-1000:
78=3075 shoots very accurately
79=3090
80=3115
81=3135 was also quite accurate
82 3205 vel jump/over the top/some bolt lift resistance



moly coated Berger 180 target VLDs, RL-33.
81= 2988
82= 3010
83= 3040
84=3075 most accurate
85=3124
86=3140 slight bolt lift resistance

Load for Mark X: 84 gr of RL-33 with 180 VLD 3075 fps

---------
As I said didn't want to buy any custom dies till I decided it would shoot. I bought a 375 Ruger die set and will use the FL die for body bump. Bought a 7 RUM die set and machined a 7 RUM seating die shorter. The 7 RUM shoulder dia is .005" larger per side but both share a 30 degree shoulder angle. Setup seating die so brass would kiss shoulder area and got low runout and decent accuracy.

To reload once fired brass I'll use the 375 die for body bump, the 338 RCM Whidden FL/ bushing die for sizing neck. Pretty straight forward.

A buddy is selling me a #7 fluted SS lilja that is 30" currently a 7 STW with 200 rounds through it for $250. I'll cut off some shank, rechamber and put it on one of my LR rifles for some testing at longer distances. Have some 180 hybrids on the way. Figure I'll get 3100-3150 pretty easily from a 29" barrel with RL-33 and the 180s.

This has been lots of fun. I think this size case is a great size for the 7mm. I hope to wack a coues wt with this rig next season.
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