408 Cheytac, rebate the rim, shorten, neck to .338

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10 years 11 months ago #31678 by SOC
408 Cheytac, rebate the rim, shorten, neck to .338 was created by SOC
I've been doing load development in my AR-10TU 300 RSAUM.

I was looking at the 50 beowulf in the AR-15 and wondered what round would make an AR-10 mag a single stack.

I picked up a 408 Cheytac round from the shelf and stuffed it in an AR-10 mag.

I could turn the head down to a 308 bolt for stronger lugs. Shorten the case and neck it to .338

Open the ejection port up and have a barrel made, Maybe a $1000 project that can be taken in stages.

Limit is if such a wide round would remove too much barrel wall thickness to hold to 62,000 cup or even 55,000.

Could always drop pressure by necking to .510 caliber and use it to launch subsonic 800-900 grain cast lead semi wad cutters...

Wondering if there is a wider case than the 408 Cheytac/.505 Gibbs but smaller than 50BMG.

My next step will be turning my first wildcat cases and getting volume/powder capacity data to run pressure calculations and estimate potential muzzle velocity.
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10 years 11 months ago #31679 by 13fcolt
Replied by 13fcolt on topic 408 Cheytac, rebate the rim, shorten, neck to .338
Well, I am certainly following this.

If I'm following you correctly, basically you are going for a short version .338snipe-tac,(cheesy name right?) so there might be pressure and load data out there to scale back from. I can't say how much case volume you would gain over .338wsm but finding load data on that might give you another reference point to gauge pressure.

If the pressure works out in .338, might be neat to run the numbers for .325 just to see how far you can go.

bulletin.accurateshooter.com/2009/01/bea...c%C2%AE-for-hunting/
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10 years 11 months ago #31694 by Libertarian623
Replied by Libertarian623 on topic 408 Cheytac, rebate the rim, shorten, neck to .338
I'll be listening intently.

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10 years 11 months ago #31699 by OleCowboy
Replied by OleCowboy on topic 408 Cheytac, rebate the rim, shorten, neck to .338
WOW, now get SOC and 13 Fox in a reloading conversation and (I have NEVER reloaded in my life) and I don't care who you are its gonna be one heck of a discussion worth following :twothumbs:

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10 years 11 months ago #31702 by MrMarty51
Replied by MrMarty51 on topic 408 Cheytac, rebate the rim, shorten, neck to .338
www.westernpowders.com/about_us
You nmight give these people a call, if You get the main office tell the person You need to find some information on reloading, they`ll patch You over to the shop.
Some mighty fine folks in there.
These people build actions for testing powders and loads, they record chamber pressures, velocities and etc. for the reloading industry, very knowledgeable peoples and they will help You in any way possible.
After You explain to them what You are building, they might have some nice recommendations to follow, might even have a caliber they have already tested that would be so close that no testing would be needed. It might even spur them into motion to build a chamber for that round and do the ballistics tests.
I can drive "UP the Yellowstone Hill" and walk in and visit whenever I have questions, that is a mile or less from My house. :rotfl: I love that place.
Maybe Mlotzi could call them and pick up a new site sponsor too. and NO, they will not sell to the general public, they know Me and I have tried. :banghead: :busted: :rotfl:
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10 years 11 months ago #31737 by Siscowet
Replied by Siscowet on topic 408 Cheytac, rebate the rim, shorten, neck to .338
This thread I am following with interest as well. :nicethread:

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10 years 11 months ago #31815 by SOC
Replied by SOC on topic 408 Cheytac, rebate the rim, shorten, neck to .338
Found a case bigger than the 408 chey/505 Gibbs

505 Gibbs

Base diameter .640 in (16.3 mm)
Rim diameter .640 in (16.3 mm)
Rim thickness .065 in (1.7 mm)
Case length 3.150 in (80.0 mm)
Overall length 3.850 in (97.8 mm)

577 Tyrannosaur

Base diameter 0.688 in (17.5 mm)
Rim diameter 0.688 in (17.5 mm)
Rim thickness 0.063 in (1.6 mm)
Case length 2.990 in (75.9 mm)
Overall length 3.710 in (94.2 mm)

Brass is bout same cost ea. But I'm poking loaders/manufacturers who have 505 Gibbs/Chey tac brass and 577 T brass with destroyed necks/shoulders cause I can still use those and they can't.
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