Which Neck Sizer to use

[elkaholic]

Which neck sizer would you guys use to size a 375 Ruger down to .338? The purpose would be to step the 375 case down to .338 on my way to a 30/375....rich

 

[elktaxi1]

i use the 338 rcm and 300rcm to step down to 7mm 375 the other option might be the 7lrm brass from gunwerks you would just need to step up to 30cal. hornady may also have brass too. we had a guy come hunt this year that has a 30 375 he got though there 1000 brench rest program sorry cant remembered what he called it and his brass was head stamped for the caliber.

 

[elkaholic]

i use the 338 rcm and 300rcm to step down to 7mm 375 the other option might be the 7lrm brass from gunwerks you would just need to step up to 30cal. hornady may also have brass too. we had a guy come hunt this year that has a 30 375 he got though there 1000 brench rest program sorry cant remembered what he called it and his brass was head stamped for the caliber.

The problem I have is I am pushing the shoulder back approx. .080" so I am first using a 375 full length to get the shoulder where it needs to be. The RCM might be ok after that (what is the shoulder diameter of the RCM?) If it is wide enough, it should work. I was thinking of a RUM, Lapua, etc., to be sure of the width?
LRM brass is out as they won't sell it unless you buy a rifle from them! I have talked to Hornady about brass but have had no luck there.
I think if I just use the 375 full length, and then the right 338 neck sizer, I can get really close and then fire form the rest to get my 40 degree shoulder. (or maybe even push it back the rest of the way with my 40 degree die when I get it)......Rich

 

[woods]

Hey elkaholic

I was told by Hornady that a neck sizer for taking down the 375 neck down to 338 would not work, you have to use a FULL LENGTH 338 die. The reason was because the neck sizer would catch the case mouth and crush the case while the full length die had a more gradual forcing cone and would work.

I can speak from experience that the 338RCM Full Length die will take the neck down without crushing the case and then the 300RCM Neck sizer will take it down to 30 caliber.

But you might get a 338 neck sizer to work, I followed their advice and got the dies mentioned above

 

[Trickymissfit]

Which neck sizer would you guys use to size a 375 Ruger down to .338? The purpose would be to step the 375 case down to .338 on my way to a 30/375....rich

if you have access to a few machines, I simply build my own die to rough in the case to size. I would make a series of bushings that had the shoulder angle machined on ne end, and the bore would be whatever I was after minus .003" for spring back. I'd probably take the neck down in three or four steps, and then finish it with a regular die. (should size the necks down .003 to .005"). You can buy hard steel bushings from a bearing reseller that will be about .100" wall thickness, and as hard as your ex wife's lawyer in court. They cut pretty easy with a ceramic insert. Of course you could also use drill bushings, but think they'll be too big in diameter. Or you could simply turn them out of A2 and have them hardened (A2 will not change during heat treat so machine to size). You can but the inner races in .312", 9mm, and .375" in various lengths. For the die body, I'd use 4150 pretreat steel, and run the chamber reamer thru it. Then cut the other end fr the bushings with a cap of some sort to hold them in place. Then after all this is done simply have it nitrided for a .025" case. (you might even be able to get by without nitride hardening being as all your doing is a neck and shoulder rework). I don't think I'd do this with a regular bushing die as I don't the the bushing retaining cap will be strong enough. You'll need something much heavier in construction. I kniow a guy that uses a similar setup to form 30 Meyer cases, and they are a bitch to form. He has to take .284 brass out to 35 caliber and then shrink the necks and push the shoulder back quite a bit. He does it in an arbor press.
gary

 

[Trickymissfit]

Hey elkaholic

I was told by Hornady that a neck sizer for taking down the 375 neck down to 338 would not work, you have to use a FULL LENGTH 338 die. The reason was because the neck sizer would catch the case mouth and crush the case while the full length die had a more gradual forcing cone and would work.

I can speak from experience that the 338RCM Full Length die will take the neck down without crushing the case and then the 300RCM Neck sizer will take it down to 30 caliber.

But you might get a 338 neck sizer to work, I followed their advice and got the dies mentioned above

that's correct. You should only size the necks down about .025" at a time. Pushing a shoulder back .08" is not gonna be even slightly fun, and is normally done is a series of steps. You should also anneal the case way beyond what you would shoot at. They'll work harden pretty good along the way.
gary

 

[Broz]

Why not buy one Redding neck bushing die and 3 bushings to do it in steps? This is how I do the 7mm - 300 win and it works golden with little runout induced.

Jeff

 

[elkaholic]

Thanks for all the input guys! What I have done is buy a full length 375 Ruger die to first push the shoulder back about .070", then use a 338 RCM die to neck down the first step. The third step would be either use my 30/375 S.I. die to create the 40 degree shoulder or maybe better yet, just fire form at this point since I have to blow the taper out a little anyway.I can use my bullet swaging press for any and all steps, so horsepower is not an issue......Rich

 

[Trickymissfit]

Why not buy one Redding neck bushing die and 3 bushings to do it in steps? This is how I do the 7mm - 300 win and it works golden with little runout induced.

Jeff

you might well ruin the die forming the necks, and they don't do angles anyway. He's bumping a large diameter shoulder down .08" as well as shrinking the neck diameter. Going from a .338" diameter to .313" diameter is easy, but going from .404" to .338" will destroy any die. Doing it in stages is the right way, but there are also large gaps in bushing sizes with no way to correct the shoulder angles. Most large diameter cases are already taxing the die body to the max with a full length resize.
gary

 

[Pdvdh]

Thanks for all the input guys! What I have done is buy a full length 375 Ruger die to first push the shoulder back about .070", then use a 338 RCM die to neck down the first step. The third step would be either use my 30/375 S.I. die to create the 40 degree shoulder or maybe better yet, just fire form at this point since I have to blow the taper out a little anyway.I can use my bullet swaging press for any and all steps, so horsepower is not an issue......Rich

Let us know how this works when you receive the dies and brass and start forming cases? I'm interested in knowing how much force is required to set the shoulder back and whether this becomes a big deal or not.

 

[elkaholic]

Let us know how this works when you receive the dies and brass and start forming cases? I'm interested in knowing how much force is required to set the shoulder back and whether this becomes a big deal or not.

Will do! I wonder what the best lube would be for this process? I'm thinking about trying some of my bullet swaging lube for copper jackets...............Rich

 

[Pdvdh]

Dunno what would be the very best. The best product I've used for case sizing is Imperial Case Wax. I could be surprised, but I don't expect this process of setting the shoulder back to be all that difficult.

And taking the necks down will be very simple provided no individual step-down process is too large. If the case neck shoulder collapses, you'll know it's time to add an extra step to the necking down process. Any pistol resizing die that you have on hand might make the neck resizing process more gentle. A 38 Special or 357 Magnum case resizing die might be an option for the first case neck reduction step. That would only be 0.018" step down in the first process. That's a very common die. If you don't own one, perhaps a friend does? Less is always best. I'd try that and see if works well.

Then move on to the 338 RCM die for another 0.019" reduction. That would turn the one-step process into a milder two-step process from .375 to .338. When I have to neck down wildcats from parent cartridges, I use anything I already have available (meaning no additional cost) to size down in smaller steps.

Another means for a two-step process between .338 and .308 could be a 325 WSM (.323") full length resizing die, if you have no-cost access to one. I do believe you'll be able to go from .375 to .338 and from .338 to .308 with just one-step each, and wouldn't spend money to break those down into two-step reductions. But if you have a no cost option to size down through a four-step process, like .375 to .357 to .338 to .323 to .308, then that's what I always try to do.

I have a relative that owns a gun shop and I have been known to borrow used reloading dies (pistol or rifle) from whatever is available there in the shop to progressively size down case necks. Which of course is helpful. But sometimes I borrow various dies from a friend, since they're only for one-time use.

 

[Pdvdh]

Re: Necking down from .308 to .257

This is what I experienced when I attempted to neck down from 300 RUM to 257 RUM in a single step. I needed a 7mm WSM or 7mm RUM full length die but must not have had one on hand. So I got impatient and tested my luck going straight down to 257. The shoulder on this casing was screaming out in pain just before collapsing!

 

[elkaholic]

Re: Necking down from .308 to .257

This is what I experienced when I attempted to neck down from 300 RUM to 257 RUM in a single step. I needed a 7mm WSM or 7mm RUM full length die but must not have had one on hand. So I got impatient and tested my luck going straight down to 257. The shoulder on this casing was screaming out in pain just before collapsing!

Ya, I've done that kind of thing as well. We should know by midweek how this process really works. I'll have to take the 375 die in to my buddies and cut it down in his shop. I think I'll cut off a little more than what I need and then use the collar to adjust back to PERFECT......Rich