Case dimensions?

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Case dimensions?

Postby Stealthshooter » Tue Jun 07, 2011 3:48 pm

I was wondering what the case dimensions are for the 300ossm? is it using the same rim diameter as it's bigger brother the 300wsm?
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Re: Case dimensions?

Postby Globemaster » Tue Jun 07, 2011 4:30 pm

it’s currently using a 25WSSM case.


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my handloaded .25WSSM on the left, and a Factory HSM® 300-OSSM on the right

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again ... the .25WSSM on the left, and a Factory HSM® 300-OSSM on the right

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again ... the .25WSSM on the left, and a Factory HSM® 300-OSSM on the right

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Re: Case dimensions?

Postby Hoot » Tue Jun 07, 2011 4:49 pm

Looking at that spent HSM case head, my first thought was good grief, they're loading them terribly hot to flatten the primer like that! Small wonder they get the velocity they do. :roll:

Rim diameter should be .535 +/- for manufacturing tolerances. I measured one of the pieces of once fired 25 WSSM brass and it was .533.

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Re: Case dimensions?

Postby Globemaster » Tue Jun 07, 2011 4:53 pm

Hoot wrote:Looking at that spent HSM case head, my first thought was good grief, they're loading them terribly hot to flatten the primer like that!

yeah, now that you mention it ... : yikes :
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Re: Case dimensions?

Postby Hoot » Tue Jun 07, 2011 6:02 pm

I for one don't like the look of the necks of 25 wssm once they're stretched up to 300 OSSM. Yeah, they seem to hold up, but looking at the 25 wssm brass before stretching, the necks look like nice homogenous brass. No stretch marks, no micro fractures, etc like the .300 necks look like. If 25 WSSM brass is made by cutting off .300 WSM brass right at the shoulder (1.66") then necking it down to .25, why would anyone stretch it back up when you can just neck the cut .300 WSM brass down to .300 and fireform it to clean up the shoulder transitions. I don't know the wall thickness at the shoulder area on 300 WSM, so neck turning or reaming might be necessary step afterward. Perhaps not. I'd probably anneal, size it down to .358 first, then the rest of the way down to .308. I bet you a dollar to a doughnut that the neck would be inherently stronger than the stretched ones. Then again, perhaps that's been tried already. If the resultant neck walls were too thick, it would seem to me that reaming would be the better than turning the outside of the necks since it would smooth out that granular finish on the inside. Just musing on a slow evening...

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Re: Case dimensions?

Postby Globemaster » Tue Jun 07, 2011 8:40 pm

I'm just glad I got out when I did; and I really admire your dedication to the art of seeking the ‘accurate load’ for this magnum upper … my hats off to all of you that are keeping the faith. :thumbs up:
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Re: Case dimensions?

Postby Hoot » Wed Jun 08, 2011 1:56 am

Globemaster wrote:I'm just glad I got out when I did; and I really admire your dedication to the art of seeking the ‘accurate load’ for this magnum upper … my hats off to all of you that are keeping the faith. :thumbs up:


All it took to start getting decent groups was dancing naked, around an inverted cross, covered with goats blood. Did the trick right there. :wink:

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Re: Case dimensions?

Postby 9x19MdM » Wed Jun 08, 2011 5:57 am

Hoot wrote:
Globemaster wrote:I'm just glad I got out when I did; and I really admire your dedication to the art of seeking the ‘accurate load’ for this magnum upper … my hats off to all of you that are keeping the faith. :thumbs up:


All it took to start getting decent groups was dancing naked, around an inverted cross, covered with goats blood. Did the trick right there. :wink:

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Re: Case dimensions?

Postby Zooka » Thu Jun 09, 2011 8:52 pm

Hoot,
I will look, but I dont think I got stretch marks with my annealed brass, and I did it in one step straight from 25 to 30. Only stretch marks I have seen was on the bodies of the 2495 loads I shot, the ones that literally stuck in the chamber, even though their velocity was not high and tracked QL predictions, and pressures in QL were within limits. Just too fast a burn initially.

GM, I am actually afraid reloading will be boring after this, as this is my first and only experience with it so far. I was telling Hoot the other day that had almost gone with a Grendel, and there have certainly been times I regretted it. However, this has been a really great education in internal and external ballistics for me! Everything else will be cake after this. Perhaps a .458 WSSM next....
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Re: Case dimensions?

Postby stdriver » Fri Jun 10, 2011 6:47 am

stealthshooter: All of the WSSM cases ie: 223.243.25 are cut down cases from the parent case which is the 300 WSM according to Winchester, so the only differences are from the start of the shoulder up to the neck
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Re: Case dimensions?

Postby Hoot » Sun Jun 12, 2011 6:44 pm

BTW, they both have a parent further upstream in the .404 Jeffery, as do many other beltless magnums. I learned that if you're going to try and make one by resizing, don't start with a case cut down to 1.66. I had a .300 RUM case laying around and tried using that starting with it cut down to 1.66. The resulting case got shorter, though I sized without the expander as I did not know how small the resulting ID would be and didn't want it to get stuck. I'm glad I did as the sized neck ID was .2775 and that's a long way from .3045. I still want to try this with a .300 WSM case, but I will probably cut it off at where the neck meets the shoulder in case it shrinks also. If the .300 WSM walls are as thick as the RUM, you will need to ream them after sizing. I sincerely believe it would be worth the trouble if you're into this caliber for the long haul as it should produce a stronger case. Of course. I could be totally wrong also.

Despite those stretch marks, the last batch I made by fireforming are doing great after two reloads. No sign of the dreaded donut. They're still getting beat up during feeding and extraction already. :roll:

I'm a little concerned about my annealing effort though. The necks, even though they are sized down to .3025 ID seem to exert less neck tension than the first batch I did without annealing, with .3045 ID necks. Hopefully, repeated reloading will harden them back up a little.

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Re: Case dimensions?

Postby stdriver » Tue Jun 14, 2011 4:55 am

hoot; I just measured the necks of several of my 25 wssm resized to 30 and they all measure .3025 using the standard method of resizing , you might want to check the size of your expander ball in the sizer die. My measures .3070 at the ogive or widest part. I only use Imperial sizing lube when I resize after a good cleaning in the tumbler.


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Re: Case dimensions?

Postby Hoot » Tue Jun 14, 2011 9:39 am

stdriver wrote:hoot; I just measured the necks of several of my 25 wssm resized to 30 and they all measure .3025 using the standard method of resizing , you might want to check the size of your expander ball in the sizer die. Mine measures .3070 at the ogive or widest part. I only use Imperial sizing lube when I resize after a good cleaning in the tumbler.

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Thanks, I'll check mine when I get home from work. Imperial is great stuff on the outside of the cases. After you resize a lot of brass, inspect your expander and see if you have a ring of brass built up on it. That's not a good thing. It can drag on the inside of the necks, increasing their size and equally important, it can cause scratches on the inside of the neck as it has significantly higher friction than the polished expander ball. it's easily removed by spinning the stem and expander in a drill while squeezing the expander in a paper towel with kroil, hoppes, or some kind of cleaner on it. Flitz works really well. Switch spots on the towell until all you see is the steel of the ball. That's one of the reasons I dust the inside of the necks with some kind of dry lubricant. It reduces the tendency for brass to build up on the expander ball.

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Re: Case dimensions?

Postby stdriver » Tue Jun 14, 2011 11:06 am

Yeah! I just finished polishing mine with fritz on a dremel polishing tool, no brass to start with, but had some scratches on the expander so did the polishing trick to a bright metallic shine.

Measured some other brass inside necks just for grins: 30-06 was .0305, 308 was .0304 and 300 WSM was .03035. all are standard brass cases of normal thickness so I think the extra thickness of the 300 WSSM brass is what's causing the extra springback of the neck after the expander has passed through IMHO.

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Re: Case dimensions?

Postby Hoot » Wed Jun 15, 2011 4:56 pm

stdriver wrote:hoot; I just measured the necks of several of my 25 wssm resized to 30 and they all measure .3025 using the standard method of resizing , you might want to check the size of your expander ball in the sizer die. My measures .3070 at the ogive or widest part. I only use Imperial sizing lube when I resize after a good cleaning in the tumbler.


stdriver


I finally got around to measuring mine and according to the micrometer, it's .3057 at the ogive or widest point when polished to a mirror finish.

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Re: Case dimensions?

Postby Zooka » Wed Jun 15, 2011 7:44 pm

Rushed for time tonight but here's a couple of measurements:
Brand new 300 WSM die expander (hornady) (opened the box just now): .3084
Gently used 30-25 WSSM expander, unpolished (Hornady): .3072
Annealed, Twice fired, resized, 30-25 brass: ID = .302 at mouth down to .304 near shoulder - slight donut.
Outside diameter (resized) top of neck, .338, increases to .343 at the shoulder. (ought to turn this one, eh?)

Unfired remington 300 WSM brass: OD from .3385 at junction of shoulder to .336 at top of neck.
ID (unresized, unfired) .298 to .300, smooth...
Darn, sorry, got to scoot, lots of distractions lately...
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Re: Case dimensions?

Postby stdriver » Thu Jun 16, 2011 5:23 am

All of my measurements were done using a analog caliper. not as exact as a micrometer, but it suits my needs for reloading

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Re: Case dimensions?

Postby Zooka » Thu Jun 16, 2011 6:35 am

OK where was I.
With analog dial caliper OD of both the .30-06 and .300 WSM necks are .335, and the WSSM goes from .337 at the top of the neck to .3415 near the shoulder. That's .006 thicker. Time to turn I guess.
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Re: Case dimensions?

Postby Hoot » Thu Jun 16, 2011 6:43 am

stdriver wrote:All of my measurements were done using a analog caliper. not as exact as a micrometer, but it suits my needs for reloading

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What's a few tenths of a mil between friends anyway. :wink:

I must say I'm saddened by the fact that my expander is slightly narrower than everyone else', yet my neck IDs are a little wider. Not much, but cause for pause. If there's anything I've learned about the Hornady New Dimension dies and I have 3 different sets, it's that Hornady is not a stickler for tight tolerances on them. The decapping / sizing die for my 6.5 Grendel was so loose as to be unusable and I bought a Forster one to use in it's place. I do however, like their seating die. The sliding bullet guide sleeve is quite a handy touch as long as your loaded rounds don't get too wide at the mouth so as to seize up in it. Makes for tricky in-place dis-assembly and you gotta keep an eye on that Oh-Jesus! clip. :|

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