Trouble necking down 300WM to 7mm with pics

[ZLBubba]

So I thought I'd try my hand at wildcatting and so far I'm coming up empty. I just got a 7mm/300WM, essentially a 300WM necked down to 7mm. I have long used Redding Type S bushing dies for my reloading so I ordered the proper bushings, as well as a 7mm Neck Die. After trying all morning to find the sweet spot between sizing the full neck length down to 7mm, I cannot do it without crushing the shoulder. If I stop once I feel the die hit the shoulder, then I'm left with about .0075-.01 length of shoulder that is still sized to .30 caliber. Obviously I cannot chamber this case. I've experimented with the positioning of the die itself press and with the position of the internal neck sizer and bushing. I cannot find a sweet spot to size the entire length of the neck without crushing the shoulder. Here's a .jpg that shows how far I can neck size before the die touches the shoulder. Note that there's a bell at the base of the neck and abrasions from where the shoulder is being contacted by the die. The shoulder doesn't have any distortions itself, but you can see that it's right at the crushing point.

Is there any way I can tweak what I'm doing with the dies to isolate the necking procedure from touching the shoulder? Are the Redding dies themselves the issue? I have tried with both Redding Type S dies in 300WM and 7mmRM with the appropriate pushing and have gotten the same bad results. Any tips would be much appreciated.

 

[Skyking]

That's normal to not be able to size the whole way down the neck. I tried the same thing with mine. Size down until you just touch the shoulder. Fire the round and then the next time you resize just bump the shoulder back.

 

[ZLBubba]

I actually can't chamber the round with the remaining bulge at the base of the neck. I've tried and the bolt isn't even close to closing. I am thinking I may have to get another die and see how that works, though I'm hoping there's something I'm overlooking that I can fix today.

 

[Weaselthis]

I use a 7RM neck die the after first running them thru a 300WM FLS or body die. I put some powdered graphite on the neck to gauge how far down I was sizing w/ the 7RM neck die thru trial and error, and once set, locked it down. I don't have a 300WM types S but that would seem to be the hot ticket. Others have mentioned this as well. You may have read some postings on LRH about it, but if not, good read:Anyone own a 7mm 300 Win Mag? - Long Range Hunting Online Magazine Good luck. Think you will like the round! Welcome to the wonderful world of wildcats.

 

[ZLBubba]

I actually think the issue may be with the Redding Type S die itself. My hypothesis is that the shoulder is a bit more aggressive since the bushing is meant to be customized to the desired neck tension. Maybe Redding thought that a weak shoulder plus the wrong bushing would lead to too much slop and complaints. Either way, at least with the Type S die, I cannot get to the base of the neck without crushing the shoulder. I've heard the Hornady 7mm Magnum neck die has more shoulder clearance to allow for the whole neck to be sized.

 

[18Echo]

Bubba, I had the same problem as you. I am having a 7-300WM made by Robert Gradous and while waiting for it did a full prep on 100 Norma 300WM cases. I also got a little worried when they didn't size down all the way using a redding type S bushing die. I started by using a .322 then .315 and finished with a .310 to expand on a mandrel to neck turn. I fixed the unsized portion by neck turning each piece to an even .014 all the way to the shoulder junction. In the below photo from right to left you have a necked down case, a neck turned case in the middle, and then on the far left a case that I accidentally went to far into the shoulder on.

 

[BobinNC]

There is a specialty case forming die made for this conversion by RCBS and sold by Midway. But it is a specialty item. I would also try to contact RCBS and Huntington Die Specialists.

RCBS Caseming Die 7mm-300 Winchester Mag

 

[ZLBubba]

Gents, thanks for the help. I'll look into both of those options. 18Echo, I sent you a PM with a few questions. Many thanks.

 

[Baron]

ZLBubba,
A 7mm WSM FL die will solve your problem! It is larger at the Shoulder/Body junction, so it will not contact the .300WM case and short enough to neck size the entire length of the .300WM neck. As long as you are not trying to make the neck length longer than parent case! Just run the 7WSM die down far enough to headspace the case (close the bolt on the sized case). If you push the shoulders back to increase the neck length, you will have donuts!
Baron Graham

 

[ZLBubba]

I've got some intermediate bushings on the way. If they don't work in my 7mmRM neck die, then I'll snag a 7WSM die and see if it works with these bushings.

 

[bjay]

Im doing this on my 7saum usibg 300 norma saum brass..with the same dues type s redding..if you want a busing that reach the shoulder get RCBS neck bushing it will go farther down and it will help you on chambering

 

[JRWALLSIII]

Some will disagre but dont neck down more than .010 at a time. Thats alot of bushings but your brass will turn out perfect with no bulge at all

I used a Redding comp micrometer die for my old APA 7/300 WSM. When I tried necking down more than .010 at a time I had issues. Once I solved the problem my brass turned out perfect. It shot great on the first firing too

 

[bjay]

Some will disagre but dont neck down more than .010 at a time. Thats alot of bushings but your brass will turn out perfect with no bulge at all

I used a Redding comp micrometer die for my old APA 7/300 WSM. When I tried necking down more than .010 at a time I had issues. Once I solved the problem my brass turned out perfect. It shot great on the first firing too

i do mine from new 334 neck to 325-317-314 done! do i think maybe i dont need 317? maybe but doing this method giving mea square good concitricity no im ok spending another 14.00 for another bushing givinbg me better concit,a;lways good to start with a body die for yoyr 7mm