M70 7mm Mashburn Super Mag

[jimbires]

are your bullets seating into the donut ? I don't think it would be a problem if your bullet is above it .

 

[SJB358]

are your bullets seating into the donut ? I don't think it would be a problem if your bullet is above it .

I think they will go into the donut eventually Jim. Right now with the fireform loads they do not go past it.

The the 175 Partitions they will eventually have to go past. I have went round and round with this as I never wanted to turn much, but I figure I should make my best attempt at doing this right.. Who knows, maybe it'll help with others.

Once I get them fireformed I'll know more. I am really thinking of getting a Lee Collet Die made for this one as well, just to eek out as much consistency as I can. I am due for some hard headed learning! :mrgreen:

 

[jimbires]

Scotty , I don't think the donut will move during the life of the brass . I understand as you work with seating depth you could end up with the bullet in the donut . you might have already thought this through instead of cutting out the donut , could you use a bushing die and not size the neck completely to the shoulder ? I've been doing this thinking it might also help align the case in the chamber . this could be something to think about if cutting the donut out doesn't work out . some of this stuff is hard to see what's going to happen until you're in up to your knees .

 

[SJB358]

I believe, not knowing exactly that once it is cut out, it is a one time deal. I guess it forms because of the shoulder becoming the neck using 300 Win Mag brass. It is only some kinds of brass as well. Most of the bullets are seated with the base of the bullet ending up somewhere in the shoulder area. None that I am aware of go any lower, but some will have to pass.

I have really thought of a bushing die as well Jim. Not sure how to get one for the Mashburn to be totally honest. I have never used one so maybe I will have to call Redding and see what they can do for me. I would absolutely like the ability to control neck tension with different bushings.

 

[longrangehunter]

Scotty, you'll only have to inside neck ream once before fireforming and then you're done. Just make sure the reamer barely touches the inside of the neck, this way you won't cut too much before it reaches the doughnut, and it usually only take a few turns to remove it.

Good luck, you're on the right track with using good brass in the first place, and the RWS brass will last almost forever, or the life of the barrel.