7mm and or 30cal Bushmaster?

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Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Wed Jan 27, 2016 7:00 am

IceAxe wrote:Hoot, thanks for tapping those cases! They look great! I am hoping Tomorrow I Can measure the distance to the lands on the RAR.
I can't wait to see your testing results with your new RAR. I thought about picking up another one just to have a spare, what a great value. Was the R15 ever offered in 450 Bushmaster?


Yes, the R15 was available in 450b.

I stopped by the local snowy rifle range and let two shots go to get some fireformed case examples. I would put the recoil on par with my 6.5 Grendel ! Image Cycled the two rounds perfectly. Interesting footnote. Within the same box of factory 150gr cartridges, there are two different looking primers. Some are brass and some are SS. Inspected the other boxes and they're the same way. Would not have expected that.

Raw fired case capacity was exactly 45gr of water. I had to resize them to push the shoulder datum point back .008, in order for them to barely chamber, which is not nearly as far back as factory loads. Moved it back to .010 and that felt more reliable. Will stay with .010. Water capacity dropped to 43.3gr after resizing.

I scoped the bore when I first cleaned it after picking it up and again after the two shots and a cleaning. Not much copper pickup, but then it was only 2 rounds. Can't wait for comfortable shooting weather to return in about 2 months.

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Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Wed Jan 27, 2016 2:29 pm

FWIW I averaged my spent cases for the 30 RAR and measured 44.8 grains H2O. I measured contact with the lands with the Hornady 130g SP an got the following means; 1.7030" Comparator and 2.1975" COL. Very close to your findings for that bullet. I also picked up some 130g TSX, they measured a mean of 1.744" comparator and 2.364" COL.
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Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Wed Jan 27, 2016 5:36 pm

IceAxe wrote:FWIW I averaged my spent cases for the 30 RAR and measured 44.8 grains H2O. I measured contact with the lands with the Hornady 130g SP an got the following means; 1.7030" Comparator and 2.1975" COL. Very close to your findings for that bullet. I also picked up some 130g TSX, they measured a mean of 1.744" comparator and 2.364" COL.


Have you had occasions where the case shoulder developed "puckers" after resizing?
Including the ones I modded for OAL gauge cases and the two yesterday, out of those 5, 1 had multiple small puckers or call them whatever you wish and 1 had a single small dimple in the shoulder area, The one with multiple puckers was my first resizing effort using the 1-fired case you sent me to make you an OAL gauge case, of course! Image I substituted a pulled new case for it. I learn fast thankfully. In that first effort, I had screwed the sizing die all the way down to where it contacted the shell holder. Since the substitute was already factory resized, I just reamed open the neck to pass the bullet. The subsequent cases I resized, including the one with one small dimple had their shoulders pushed back only .010. Die and cases were not overly slavered up with Imperial wax. Not too concerned until I get the chance to shoot and process a lot of them at the same time.

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Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Wed Jan 27, 2016 5:53 pm

I have dimpled many cases, but it has always been when using too much case lube, generally when lubing the case mouth with a Q-tip.
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Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Wed Jan 27, 2016 7:30 pm

IceAxe wrote:I have dimpled many cases, but it has always been when using too much case lube, generally when lubing the case mouth with a Q-tip.


Everyone has their methodology. I swipe my index finger lightly across the top of the Imperial wax, rub it against my thumb and middle finger until each has the same fine layer on them, switch hands and repeat. I then pick up the cases and spin them between my thumbs and fingers. This is starting to sound lurid, so I'll quit while I'm ahead. That's not my typical overly verbose description, but it's really simple and has served me well for years. I can usually do 10-12 cases with a finger swipe. Imperial wax goes a long way as do other products. BTW, Imperial wax really softens your skin, but there we go in the TMI direction again. ;)
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Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Thu Jan 28, 2016 9:09 pm

The good news is it can be done:

Image

The bad news is the neck wall as you might expect, is twice as thick as it should be, requiring reaming. Possibly reaming before resizing is the way to go. Tried turning the outside of the neck on another one, in the lathe and it didn't look right. Major step where the turned down neck meets the shoulder. Might be able to fireform, but that adds an extra burden.

Steps:
Pre Cut down the case as they grow in length as you narrow them down
Anneal
Lube
Resize down to form the shoulder
ReLube
Finish sizing

I did this more to satisfy an itch than to suggest this as an alternative to just buying ammo for the brass.

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Re: 7mm and or 30cal Bushmaster?

Postby PRKL8R » Thu Jan 28, 2016 10:36 pm

That would save if you have a lot of .450s on hand. Maybe you could reclaim some .450s that grown too short. I was wondering if the different rim diameter works as the .450 is 0.476 and the .30 RAR was purposely made 0.492 to prevent it being fired in a .450. BTW where are you guys finding these bargain prices. Im interested.
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Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Thu Jan 28, 2016 10:46 pm

PRKL8R wrote:That would save if you have a lot of .450s on hand. Maybe you could reclaim some .450s that grown too short. I was wondering if the different rim diameter works as the .450 is 0.476 and the .30 RAR was purposely made 0.492 to prevent it being fired in a .450. BTW where are you guys finding these bargain prices. Im interested.


Bargain prices on what? The rifles? Tin Star Range will ship you one for $721. After I ordered mine from Tin Star I saw that grabagun has them for $697.45 + $5.99 flat rate shipping. My 30RAR cycles the smaller rim 450b cases by hand. Haven't actually tried shooting one resized down though, so not sure if it works equally well at regular cycling speeds.

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Edit: slickguns said $697.45 but at the grabagunsite, it was $714.45
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Re: 7mm and or 30cal Bushmaster?

Postby Al in Mi » Fri Jan 29, 2016 5:41 am

hoot, and difference in case capacity?
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Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Fri Jan 29, 2016 6:41 am

Al in Mi wrote:hoot, and difference in case capacity?


I haven't measured it yet since past experience suggests fire forming to get the I's dotted and the T's crossed first. I can tell you that without reaming the neck to the correct wall thickness, the case weighed about 30gr more than an empty piece of factory brass. 30gr of brass isn't as much as you'd think. In its non-final stage, I would not be surprised if a good portion of that weight correlates directly to water capacity. I will check it tonight. Once new ammo is no longer produced and the remaining NOS becomes prohibitively expensive (look at all the WSSM orphans) there will be a point where it is the only solution. I'll probably lose interest in this caliber before resizing 450b cases winds up being the only solution. ;)

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