it can be done if you have the right equipment. biggest problem is your necks end up .010-.012 at the mouth and .018-.020 at the shoulder because you bring so much shoulder material into the neck. multistage expanders and proper annealing with neck turning and your ready to go.
300prc to 375 ruger ?
- Thread starter crazymonkey
- Start date
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The test brass arrived today a free box of once fired hornady 300 prc . Just need to order expander dies and a few different mandrels . Worst case senerio I split some necks and waste some $$ that I'd just **** away anyway. I've stretched 30-30 up to 357 before with good results but this is a wee bit more.
i have taken the SAUM case to .416 and .429 just takes patience and good lube. don't be in a rush, push expanders slowly giving the brass time to stretch going fast will cause splits or collapse shoulder.
always thought a 44 SAUM with 18" barrel and 300 grainers would be a thumper.
always thought a 44 SAUM with 18" barrel and 300 grainers would be a thumper.
It will work just fine and you don't need special dies to do it. Run the brass through your 375 neck die then the FL die. Anneal the brass. As you can see from the drawings, shoulder angle, location and length are almost the same, all you are actually doing is opening up the case mouth and that will slightly thin the brass, not make it thicker. I have taken 378 Bee to 460 and taken 460 to 338-378, just using the regualr Redding dies.
460 Bee to 338-378. Right to left, first step 378 seating die, second 378 FL die, fourth and fifth case 338 seating die partial then seating die all the way, then sixth case, 338 FL die. No neck turning was required.
460 Bee to 338-378. Right to left, first step 378 seating die, second 378 FL die, fourth and fifth case 338 seating die partial then seating die all the way, then sixth case, 338 FL die. No neck turning was required.
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I ordered some expander dies this morning . I'm going to try and two step expand with annealing then full size .The test brass is hornady and softer than the brass I'd plan on running adg or lapua there a lot harder brass than the hornady.
8x68s
Well-Known Member
It's been around this long for good reason! I have a Browning B78, 300 H&H and a wildcatted 78 in a 330HNH (my call name). I'd like to do one more in .375 to finish the series.
I just got the email yesterday from rcbs that the expander dies are on there way . I'll probably have them in a few days and test some brass shortly there after . The plan is to annealing the neck and come up to 338 then I'll try to go to 375 . I might need to anneal again before I try it but the brass will tell me quickly what works . Then I'm going to run thru a 375 ruger full size die to set the shoulder and fire form to get it where I need everything to live .
The expander dies made it in today . So I took 3 rounds to test . I annealed the necks and started with the 348 die with some one shot for case lube and went slow . No trouble with it. Then swapped dies to the 375 expander and went slow but pushed in the neck . Probably my fault I didn't have the die set high enough . Gave it another go with the die higher and success. The neck didn't loose to much in thickness the case length is .02 under . It might get there once the case is fire formed to push the shoulder . But so far it is possible and should work. I'd even say it's possible to just use one expander and then run a full size die . I'm going to test this also .
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You will lose less thickness if you don't anneal them first. They will also form easier. Give one a try not annealed, i think you will be please with how much easier it is. The 2 step expansion is much easier on the brass even though one step will work.
I'll give it a test . I've got 20 rds of free brass to try before I pony up for the good stuff . I'd like to get everything 100% before I run lapua or another quality brass .
You will thin the neck regardless, it will be easier if you anneal.
I have formed many, many thousand brass both up and down. (SEE 460 BEE to 338 378 above as one example) I have tried every combination and permutation possible. I have developed my process to the point I no longer need any special forming dies, I can do all of it using just a variety of seating, FL and Neck dies. You can choose not to believe my experience if you like but I can guarantee that annealed brass does not form as well or easly unless it is extraordinarily hard, as in it has been shot and loaded 6 or more times. Annealing after forming, to prevent neck or shoulder splits when fire forming is however a very good idea because forming work hardens the brass and the more you move it, the more it hardens. It will however never split, not will it crush as easily during forming if it isn't annealed.
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My experience with sizing up brass is limited to just my Contender in 357 harret . It's cut down 30-30 then necked up to 357. With this I tried to size up without annealing and would split necks . After I annealed I had no problem . This is a different animal as it's necked and has a shoulder . I'm going to test every option and see what gives the best results. I'm just happy
as heck it works. I'm thankful for all the help also .
