7mm Dies w/37 deg Shoulder on 300WM Parent Case

[chuckhammer]

Had a nice conversation with Dave Kiff at PTG on Friday. I'm planning to have a reamer made for a 7mm-300 Win Mag "Improved" project gun on a Savage 110 action. He convinced me that a 37 deg shoulder would be perfect. For comparison, 300 WM and 7mm RM are 25 deg. I also plan to go with .007" less body taper than the parent 300 WM (.496" vs. .489" @ body-to-shoulder). Dave said this falls within the minimum .009" per inch of length body taper needed for reliable extraction.

Few questions about dies:

Neck Sizing
I can do the initial 300--->7mm neck size reduction using a standard 7mm RM neck sizing die raised up .120" on the press to account for the longer 300 WM case. I did some trials this past weekend and it went well. Although this is a neck-only resizing die, I noticed it still has a shoulder. Since my chamber will have a 37 deg shoulder I don't believe I can use this die for neck sizing my fire-formed brass. Do the bushing-style neck dies have enough shoulder clearance to be able to re-size the entire neck of this case? If so, since the body taper is slightly reduced (case is .007" fatter at the base of the shoulder) will this prevent a typical 7mm RM or 300 WM bushing-style neck die from working with standard bushings?

Bullet Seating
The 7mm RM RCBS Gold Medal micrometer seating die works with a straight 7mm-300 WM since the shoulder is identical. However, with the 37 deg fire-formed shoulder, I believe this die's shoulder will prevent me from fully seating bullets. Is there a better option? I guess I can turn the die's shoulder back on a lathe but would rather find a cleaner solution.

Body Sizing
With the sharp 37 deg shoulder Dave tells me I may not need to ever bump the shoulder back with a body die. However, if the need does arise, I'm guessing I'll need to order a custom die? I'm not aware of any mainstream SAAMI or wildcat cartridges with a 37 deg shoulder.

Thanks for any help you can offer.

 

[Aeon1]

If you end up needing a full length die you can order a die reamer from Kiff later. Newlon blanks work but for best results it'll need to be hardened but not required. There are others out there that can make up a die especially if you have a die reamer. Maybe Whidden (he might be CNCing them so may only need a reamer print), Niel Jones (only needs fired cases) , Jim Carstenen, etc..

What neck shoulder radius did Kiff reccomend? I'll guess .060".

PS: I've been mulling over something along these lines as well so I'll be interested in what you end up doing. The 7-300 Practical peaked my interest and I've a spare 7mm barrel and long action waiting for the right cartridge.

 

[chuckhammer]

If you end up needing a full length die you can order a die reamer from Kiff later. Newlon blanks work but for best results it'll need to be hardened but not required. There are others out there that can make up a die especially if you have a die reamer. Maybe Whidden (he might be CNCing them so may only need a reamer print), Niel Jones (only needs fired cases) , Jim Carstenen, etc..

What neck shoulder radius did Kiff reccomend? I'll guess .060".

PS: I've been mulling over something along these lines as well so I'll be interested in what you end up doing. The 7-300 Practical peaked my interest and I've a spare 7mm barrel and long action waiting for the right cartridge.

I don't recall him recommending a specific neck-to-shoulder radius. The 7 Practical was kind of my starting point. This one will be very similar. I agree, the 300WM case has a lot to offer when paired with the heavy 7mm bullets. Thanks for the die-making references. I'll keep them in mind if/when the time comes.

Gents,
I bolded the most important part of my post. I know you guys hate reading. ;-)

 

[Aeon1]

Had a nice conversation with Dave Kiff at PTG on Friday. I'm planning to have a reamer made for a 7mm-300 Win Mag "Improved" project gun on a Savage 110 action. He convinced me that a 37 deg shoulder would be perfect. For comparison, 300 WM and 7mm RM are 25 deg. I also plan to go with .007" less body taper than the parent 300 WM (.496" vs. .489" @ body-to-shoulder). Dave said this falls within the minimum .009" per inch of length body taper needed for reliable extraction.

Few questions about dies:

Neck Sizing
I can do the initial 300--->7mm neck size reduction using a standard 7mm RM neck sizing die raised up .120" on the press to account for the longer 300 WM case. I did some trials this past weekend and it went well. Although this is a neck-only resizing die, I noticed it still has a shoulder. Since my chamber will have a 37 deg shoulder I don't believe I can use this die for neck sizing my fire-formed brass. Do the bushing-style neck dies have enough shoulder clearance to be able to re-size the entire neck of this case? If so, since the body taper is slightly reduced (case is .007" fatter at the base of the shoulder) will this prevent a typical 7mm RM or 300 WM bushing-style neck die from working with standard bushings?

Bullet Seating
The 7mm RM RCBS Gold Medal micrometer seating die works with a straight 7mm-300 WM since the shoulder is identical. However, with the 37 deg fire-formed shoulder, I believe this die's shoulder will prevent me from fully seating bullets. Is there a better option? I guess I can turn the die's shoulder back on a lathe but would rather find a cleaner solution.

Body Sizing
With the sharp 37 deg shoulder Dave tells me I may not need to ever bump the shoulder back with a body die. However, if the need does arise, I'm guessing I'll need to order a custom die? I'm not aware of any mainstream SAAMI or wildcat cartridges with a 37 deg shoulder.

Thanks for any help you can offer.

Neck Sizing

A standard off the shelf non-modified neck die in my opinion will not work. The reduced body taper and larger diameter shoulder will prevent the case from fully seating in the die or even close enough to use. You will have to modify an existing die. I have modified both Redding Comp neck sizers and Wilson inline dies. I have also made dies from Newlon Precision blanks. The Redding sleeves in the comp dies are soft and can be reamed with your chambering reamer. Sleeve blanks were also available in the past as well. Same with Wilson, modify an existing die or buy a blank. I would think a 300WM die in either would work fine. A Newlon blank is probably the easiest and cheapest option for a neck die and it's probably what I'd use. They use Redding bushings.

Bullet Seating

Almost same answer as above but I would start with a 7mm version of a pre-existing die to modify, like the 7 RM. I can't comment on modifying an RCBS die like the one you referenced because I've never touched one. I know the Redding sleeve would be a touch short but I don't think it would matter. You could search and find another cartridge with a closer length to the WM and use it. You can get a Wilson inline blank and finish to length. Of course you'd have to have an arbor press to use the Wilson inline dies. Newlon also makes seating blanks and this may work but I've had mixed results with fixed plug seating dies. Sometimes they are great and you can get low runout but other times all I get is frustration. I've had more consistent results with a Redding comp or Wilson inlines.

All this reminds me why I don't mess with wildcat's too often anymore.

 

[chuckhammer]

Now we're getting somewhere! I knew I joined this place to do more than oogle other people's $6k rigs. ;-)

Neck Sizing
Guess I'll use the standard neck die for initial forming from 300WM. I'll also get a 300WM bushing neck die and use my reamer to hog out the the shoulder and remove the extra body taper. This will be used on the fire-formed brass. Modifying the Redding Comp sounds easier than starting with a Newlon blank as I don't have easy access to a machine shop. Or is doing either one by hand a bad idea?

Seating
No arbor press (yet) so I'll have to stick with threaded dies for now. Bad news on RCBS dies? I've had good experiences with them but I'll admit I not a sub-1/2 minute shooter........at least not consistently. It looks like the 300WM sleeve in my Gold Medal die can be hogged out similar to the above neck bushing die approach. Can't use the reamer for that since it will open up the neck way too much. Will need to mail it off to my friend who has a machine shop and have him turn it on the lathe or end mill. Or, if you insist the RCBS gear is basically a set of paper weights, maybe I'll do the same thing using a Redding Comp micrometer seater.

Thanks for sharing your knowledge. Keep it comin'.

 

[Aeon1]

Now we're getting somewhere! I knew I joined this place to do more than oogle other people's $6k rigs. ;-)

Neck Sizing
Guess I'll use the standard neck die for initial forming from 300WM. I'll also get a 300WM bushing neck die and use my reamer to hog out the the shoulder and remove the extra body taper. This will be used on the fire-formed brass. Modifying the Redding Comp sounds easier than starting with a Newlon blank as I don't have easy access to a machine shop. Or is doing either one by hand a bad idea?

Seating
No arbor press (yet) so I'll have to stick with threaded dies for now. Bad news on RCBS dies? I've had good experiences with them but I'll admit I not a sub-1/2 minute shooter........at least not consistently. It looks like the 300WM sleeve in my Gold Medal die can be hogged out similar to the above neck bushing die approach. Can't use the reamer for that since it will open up the neck way too much. Will need to mail it off to my friend who has a machine shop and have him turn it on the lathe or end mill. Or, if you insist the RCBS gear is basically a set of paper weights, maybe I'll do the same thing using a Redding Comp micrometer seater.

Thanks for sharing your knowledge. Keep it comin'.

I was not disparaging your RCBS dies as they may be fine, I just don't have any experience with them. I meant it literally when I said "I haven't touched one" and nothing more so I can't comment on modifying it.

It's late but here are some rambling thoughts:

Who is going to chamber this for you? Many gunsmiths are versed in reaming dies and will provide/make them when they chamber a barrel. Find yourself someone who will make you a die from a Newlon blank or an old barrel they have saved for this purpose. I'll bet you might find someone who'd ream a sleeve for the seat die as well.

or Mail off a sizing and seating sleeve to your buddy along with the reamer and let him do it.

I would not hand ream any die or sleeve for this purpose. Not saying you can't but it wouldn't be my preference. That said I have the equipment to do these things.

You said "It looks like the 300WM sleeve in my Gold Medal die can be hogged out similar to the above neck bushing die approach. Can't use the reamer for that since it will open up the neck way too much.". I'm not quite sure what you meant.

 

[chuckhammer]

Haven't yet decided on a barrel make or supplier. Looking like either Jim Briggs at NSS with a McGowan or maybe a Douglas from Sharp Shooters Supply. Brux is probably a bit more than I want to spend at this point. Maybe for the next one. I'll definitely ask about getting die blanks reamed.

My statement about using the chamber reamer to modify the seating die sleeve:
Since the neck portion of the reamer will be .316 diam, wouldn't this be too large for the seating die? Sizing down from .308 to .284 in my current standard neck sizing die they are running .307-.308 w/no turning. Loaded rounds are right at .311.

 

[Aeon1]

My statement about using the chamber reamer to modify the seating die sleeve:

Since the neck portion of the reamer will be .316 diam, wouldn't this be too large for the seating die? Sizing down from .308 to .284 in my current standard neck sizing die they are running .307-.308 w/no turning. Loaded rounds are right at .311.

If you could look at a Redding sleeve (or a Wilson inline die) it looks just like a chamber with all freebore and no tapered throat. If your reamer is ordered with a typical match freebore diameter (typically .0005" over nominal bullet dia) which in your case would be .2845" it would most likely not touch the seat stem bore at all and for sure it wouldn't touch the stem bore on a 300WM die.

I have no idea if any of the above is applicable to modifying the RCBS Gold Medal dies.

I know some people are using the sliding sleeve seaters in a caliber larger than what it was designed for. I have not done this so I don't know how well it works. If it were me, I think I'd find a 7mm die to modify if I could.

 

[chuckhammer]

Aeon1, here's a cross-section of the Redding Comp Seater Die. Never mind me. I was thinking the reamer diam forward of the shoulder would be .316 for the remaining length, thus it would need to pass through the freebore (.2845) section of the sleeve. I follow you now.

Any interest in reviewing the first draft of my reamer print? I can e-mail you the PDF. I do appreciate feedback from those who've been there already.

 

[Aeon1]

Sure, PM me your address and I will reply.

Do you have brass? I'd like to see some dimensions on the brass you will use.

 

[chuckhammer]

Finalized the reamer print. Dave only tweaked two of my original dimensions, each by less than .002. Not bad for a reamer newbie! I drew it up in ANSYS and then Unigraphics so that helped sort out the exact dimensions. Went into the production queue today, print #52542:

I christened it the Valkyrie, a buxom Nordic blonde goddess who is the “chooser of the slain.” It’s also a reference to the XB-70 Valkyrie, an experimental Mach 3 strategic bomber from the ‘60s.

QuickLOAD ***estimated*** ballistics (28” barrel; 66k psi max pressure; conservative):
Generic 100 gr Varmint Bullet @ 4175 fps
Generic 110 gr Varmint Bullet @ 4075 fps
Generic 120 gr Medium Game Bullet @ 3975 fps
Generic 140 gr Large Game Bullet @ 3775 fps
Generic 150 gr Large Game Bullet @ 3650 fps
Hornady 162 gr A-Max @ 3500 fps
Berger 168 gr VLD @ 3400 fps
Berger 180 gr VLD @ 3200 fps (what my chamber’s throat was designed for)

Here it is with a few other comparable cartridges. Parent 300WM on the right:

 

[Aeon1]

Looks nice. I see you/he went with .060" at neck shoulder. You went with a 2°-30 throat (same as the 7 Practical), curious as to reason for that? Not questioning or saying it's bad just curious.

 

[chuckhammer]

Yep, the 2°-30' throat angle is a direct copy from Nate Foster's 7mm Practical. The .060 neck/shoulder max radius was taken from your comments here. I figured it made sense to maximize the short neck length as much as possible. Thanks for that.

Just ordered the barrel today through Jim Briggs at Northland Shooters Supply:
Criterion (CBI)
410 SS
28" Finished Length
1/9 Twist
11° Crown
1" Bull Contour
14-16 Week Lead Time

Jim figures I'm looking at ~1000 rds throat life, even if I allow it to cool between shots. I plan to shoot mostly 162-180gr bullets with slow powder. What are your thoughts on expected throat life?

 

[Aeon1]

I guess my guess would be around the same

Actually the .060" is to help minimize case lengthening, excessive trimming issues. Opposite of what Nate Foster was after. I seem to remember reading he wanted his cases to stretch to help lengthen the neck. Maybe he's got something there but my experience says when cases stretch it eventually leads to casehead separations.

 

[scpaul]

Just curious how much case volume are you gaining & how similar is this to an Ackley treatment? I'm in the process of building a very similar rifle. I've already talked w/Michelle @ PTG reguarding reamers,have the action, ordered a Boyd's heavy varmint stock,and am looking at a custom McGowen bbl. Anything that I've missed or advice would be greatly appreciated. Thanks scpaul

 

[Powermac]

I christened it the Valkyrie, a buxom Nordic blonde goddess who is the “chooser of the slain.”

A bit off topic but you apparently have no clue about Norse Mythology.
Valkyries are not a goddes, and not one.
Valkyries are female death wraiths, Odin sends out to watch over all battles and wars.
And they decide who will die, and be taken to Åsgard, where they will fight alongside the gods in daytime.
And feast and drink in Valhalla at night.

Hrist, Mist, Skeggjold, Skogul, Hild, Trud, Hlokk, Hærfjotur, Goll, Geirölul, Randgrid, Rådgrid and Reginleif.
Are some of the Valkyries.

Your Buxxom Blonde would be the Goddess Freya.

Your cartidge design looks promising though, for a high capacity 7mm i am more partial to the 7 LRM though with it's beltless case and longer neck.
Just too bad everything is proprietary Gunwerks.

And i just realized this was another revived thread.

 

[chuckhammer]

Just curious how much case volume are you gaining & how similar is this to an Ackley treatment? I'm in the process of building a very similar rifle. I've already talked w/Michelle @ PTG reguarding reamers,have the action, ordered a Boyd's heavy varmint stock,and am looking at a custom McGowen bbl. Anything that I've missed or advice would be greatly appreciated. Thanks scpaul

Here's my thread on the custom Savage 110 I built recently, chambered for my Valkyrie cartridge. Reading through my experience should help.

http://www.snipershide.com/shooting...559-savage-110-custom-build-7mm-valkyrie.html

After reading Powermac's lesson in Norse mythology, I suppose I'll have to stick with the XB-70 half of the reference!