Full length resizing question.

coyoteking

coyoteking

CGN frequent flyer
Rating - 100%
33   0   0
Location
SW Sask
Bear with me, I’m an inexperienced reloader.

I’m loading 300 RUM for the first time. All my brass is once fired Remington. I’m using a Hornady custom grade fl sizing die.

When I run an unsized case into my rifle there is very little resistance when closing the bolt.

I set the die as per the instructions, just so it’s touching the shell holder. After running the same case through the sizer at this position, there’s a lot of resistance when closing the bolt.

I screwed the die in about 1/16th of a turn and tried again with a different case. Now I have very little resistance when closing the bolt, about the same as an unsized case.

How far would screwing in that die 1/16th of a turn move back the shoulder?

Is a tight fitting shoulder in the chamber with a little resistance when closing the bolt going to create a dangerous situation, or should I leave the die set where it is currently?
 
You should get yourself a Hornady bump gage or an equivalent.. It is very easy to use,comes with instructions and several cylinders covering most cartridges. If you don't I would continue to screw your sizer die down till a sized case chambers with very little resistance. I feel to set the die properly this way your fired case should be fired at least 3 times so as to fully fire form to your chamber.
 
I've not reloaded RUM cases, but I have seen similar with 308, 30-06 and 7x57. I believe that as you run the case up into the die, you are squishing the body smaller. This has to make the case grow longer, pushing the shoulder forward. I have one rifle/die combination that I intended to try "partial sizing". I started with about 1/16 clearance between bottom of die and shell holder, the "resized" brass would no longer chamber into the rifle it was fired in. Continued to turn the die down, try it, gradually got to where the "sized" case did just barely chamber, then finally get it chambering freely. Since that episode, I just set that die onto the press so it "cams over" and resize.
 
This is one of those "do you want the easy answer or the right answer" issues.

Easy answer is that the die threads are 14 threads per inch or 71 thousands of an inch per turn. 1/16s of a turn is going work out to around 4 1/2 thousandths of an inch. Bit of rounding going on there, but 4 thousandths is a long way on a shoulder.

The somewhat harder answer is that shoulder bump is very much a moving target. Depending whether your press cams over or not screwing the die in until it touches the shellholder may not even touch the bottom of the die under load. Many presses need at least 1/4 turn of extra preload to get a FL size. Presses have more flex than people think, and FL sized cases actually get longer before they get shorter. The answer to how far a 1/16th of a turn will bump the shoulder is "It depends".

If you really want to control the shoulder bump get a set of Redding Competition seaters. I don't think you need them, my impression is you just want to load some ammo?
 
The Whidden bushing die does FL size. It's right there in the name "Whidden Gunworks Full Length Bushing Sizer Die".

http://www.whiddengunworks.com/reloading-dies/ said:
Our hand-polished sizer die has a shorter OAL for better shoulder bump-back, a smaller base, and tighter internal tolerances.
Click to expand...
 
hunters home said:
You should get yourself a Hornady bump gage or an equivalent.. It is very easy to use,comes with instructions and several cylinders covering most cartridges. If you don't I would continue to screw your sizer die down till a sized case chambers with very little resistance. I feel to set the die properly this way your fired case should be fired at least 3 times so as to fully fire form to your chamber.
Click to expand...

I’ve got one on the way but it’s on backorder, I’ll probably just have to wait till it gets here.
 
Dogleg said:
This is one of those "do you want the easy answer or the right answer" issues.

Easy answer is that the die threads are 14 threads per inch or 71 thousands of an inch per turn. 1/16s of a turn is going work out to around 4 1/2 thousandths of an inch. Bit of rounding going on there, but 4 thousandths is a long way on a shoulder.

The somewhat harder answer is that shoulder bump is very much a moving target. Depending whether your press cams over or not screwing the die in until it touches the shellholder may not even touch the bottom of the die under load. Many presses need at least 1/4 turn of extra preload to get a FL size. Presses have more flex than people think, and FL sized cases actually get longer before they get shorter. The answer to how far a 1/16th of a turn will bump the shoulder is "It depends".

If you really want to control the shoulder bump get a set of Redding Competition seaters. I don't think you need them, my impression is you just want to load some ammo?
Click to expand...

Thanks for clearing that up for me, that was very helpful. This is stuff I’m loading for my go-to big game rifle so realistically it only has to be minute of deer accurate, but I’m trying to learn good practices for when I start loading for my long range target rifles.

I guess I’ll probably just hold off until my Hornady headspace gauges get here.
 
6MT said:
If you took the bushing out of the die and ran the case again, you would see that the die doesn't touch the case.
Click to expand...

Of course it won't, you already sized the body the first time you ran the case through.

It does not full length size the case. It sizes the neck and (with proper depth setting) bumps the shoulder.
Click to expand...

So Whidden is lying when they call it a Full Length Sizer?
 
Yes, I own one. No, its called Whidden Bushing Full Length Sizer. http://www.whiddengunworks.com/product/sizer-reloading-dies/ They don't sell a Bushing neck only sizer.

ZR4Qf0Rl.jpg
 
Was having the same problem with the same Hornady dies in 308. Instructions don’t say to do anything more than touch the die to the shell holder, but my brass wouldn’t chamber until I turned it down a little more.
 
Once you have your case length gauges, you'll be able to measure accurately to the shoulder.
Is the 300 RUM a belted magnum? If so, I seem to recall others having issues with tight chambering with belted magnums after resizing. If the case dimensions to the shoulder are correct, then something else is the problem.

Use your best judgement, and don't be afraid to get in touch with the die and press manufacturer. Their tech support can be a great resource.
 
Last edited:
Sheesh - For those of us that have been resizing for years, somehow we've managed to do it without all the metrological gizmos. Most die sets instruct you to turn the die in a fraction of a turn beyond snug with the shellholder. For those of us that wanted to get fancy, we would partially resize by incrementally adjusting the die until light resistance was encountered when chambering. Given the natural variation in the brass and resizing process, I would then turn in the die by a small amount, say 1/16 of a turn - such that the odd obstinate case was avoided (my reloading are generally "hunting capable")
OP - you've just found the sweet spot for that brass. Record the die setting for future reference...
 
If the fired case rechambers easy without resizing it and then when you run it in and out of the the die it does not chamber easy i would suspect the expander is pulling the shoulder up try using lube in the case neck.
 
Some presses cam over and others don't. The instructions for setting dies for a cam over press aren't enough to get a full size from a press that doesn't. The instructions for your Hornady die would be fine for my Hornady press, and wrong for my RCBS. On a Lee press they would call for touching plus 1/4 to a 1/3 turn more. It looks like you've solved your own problem already.

You can rest assured that another 1/16th of a turn on a case that barely let the bolt close isn't going to hurt anything. In fact it sounds about perfect.
 
You must log in or register to reply here.
Back
Top Bottom