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Post by Lee Martin on Feb 13, 2013 13:33:09 GMT -5
I was digging through my reloading bench and ran across this abomination:  After my dad built his first 50 BMG in 1991 we thought about making it a switch barrel. Being unaware of Skip Talbot’s work with necked BMGs we designed the “340 Deathray”. It’s basically a 50 BMG squeezed to 338 and improved to 25 degrees (this iteration isn’t fire-formed). We built reamers and dies but never the gun. Sometime around 1994 I read about Skip’s experience with his 338 Talbot and that sand-bagged the project. 177.0 grains of 8700 could be safely ignited behind a 250 gr bullet but charge density was low. 77% to be exact. That combination only returned 3,700 fps from a 44” barrel. In an attempt to bolster charge density he cut the case by an inch. Like its bigger brethren the smaller Talbot topped out at 3,700 fps. By comparison a 340 Weatherby can hit 2,600 fps with a 250 gr. The 338-378 and 338 Lapua can do 2,800 – 2,900 fps with half as much powder and a much shorter package. Diminishing returns on steroids, right? We may resurrect this thing just for giggles. Surplus powders along with commercial grades like US 869 may be fun behind a Barnes banded solid. 4,000 fps would be a stretch but it'd be neat trying to get there. Anyways, I thought some of you’d get a kick out of this. I’ll keep you guys posted if we proceed. -Lee www.singleactions.com"Building carpal tunnel one round at a time" |
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jwp475
.375 Atomic
Posts: 1,084
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Post by jwp475 on Feb 13, 2013 13:39:38 GMT -5
The 408 Cheytac necked to 338 can push a 300 SMK 3400 to 3450 fps from a 30" barrel
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Post by bradshaw on Feb 13, 2013 22:31:56 GMT -5
Lee.... your .340 Deathray looks like an upscaled .17/.220 Swift.
I think JWP hints at a 300 grain as approaching overbore potential with a .338 bullet. As we discussed, the .50 Spotter round----which is to the .50 BMG what the .308 is to the .30-06----might be a ticket puncher with .50 BMG powder.
As Curmugeon noted, there are powders around.... the General Electric Gattling guns in 20mm, 25mm, and monster seven barrel 30mm Gau 8 burn powders which I imagine Hodgdon and TRW know about (and that may be an understatement). Interestingly, the Gattling guns prize heavy for caliber projectiles with respectable velocities.
A .338/.50 Spotter----call the cartridge the 338 SPOTTER----might turn high V; and with a long neck to seat the 300 grain boat tail heal at the base of the neck, reduced throat erosion.
These are not carbine rounds; carbine barrels need not apply.
David Bradshaw
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Post by squawberryman on Feb 17, 2013 13:35:25 GMT -5
Last year while talkng with Alan Warner about something he was working on for me, he eluded to the fact that civilian stuff got done whent hey had time. I asked what they might be working on to which he replied "Let's just say what if you had a thirty caliber projectile in a 50 BMG case you could snipe with, pretty flat huh?". The laughter that followed from him was damn eerie in a wicked cool way.
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Post by Lee Martin on Feb 18, 2013 10:39:36 GMT -5
The Army experimented with a 50 BMG necked to .30-cal back in the early 1950's. I have data, the case specs, and a photo of the cartridge someplace. If I can find them I'll update the thread. If I remember correctly they used WC872 and the results were lack-luster. Now sabotted 30's in a 50 BMG is another story. David - our discussion around the 378 Weatherby moved me to build one. The dies and brass are ordered and we'll cut the reamer soon. I have a few options on the action and we'll discuss them the next time we talk. And I couldn't agree more. The 378 is an absolute sleeper for long range. 300+ grain banded solids at 3,000+ fps would shoot on a line. I'm leaning towards 31 - 32" of barrrel plus a 3" brake. -Lee www.singleactions.com"Building carpal tunnel one round at a time" |
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Post by bradshaw on Feb 18, 2013 13:10:02 GMT -5
Wise move, Lee, to build on .378 Weatherby. That was one of Roy's great designs in coordinating cartridge case to bore (.300 and .257 Weatherby's come to mind). Haven't looked at particulars of .338 Lapua, but it might be a natural in .375. I hear brass complaints on the .338 Rem Ultra Mag from handloaders; which brass, far as I know, comes only from Remington.
A savage action might work, or a home made Mike Walker (M700). A solid bottom (single shot) might cut down vibration behind the locking lugs.
Feel confident you would appreciate the .50 BMG falling block Jon Powers built.
David
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Post by Lee Martin on Feb 18, 2013 13:33:14 GMT -5
It's funny David, there are a lot of Johnny come lately 1,000 yard rounds. Nothing against them, but Roy's old 378 from '53 runs neck and neck on performance. Bullet selection is critical and I'm looking at something like Barnes banded solid except in spire-point. Sierra's 350 gr Match King is another candidate. We could also cut our own solids from brass stock using our tracer lathe. That way I could experiment with bore-rider designs. On the receiver we'll either make our own (probably a single-shot port bolt action) or use a commercial grade. I have an idea on the latter that I want to run by you first. -Lee www.singleactions.com"Building carpal tunnel one round at a time" |
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Post by kaytod on Feb 22, 2013 21:39:18 GMT -5
Lee, Check out Lehigh bullets, they have a .375 banded LRS/VLD style match bullet Here is the link www.lehighbullets.com/products.asp?cat=30Here is a pic  Discription The .375 Match Hybrid BoreRider is a premium match bullet specifically designed for long range accuracy in .375 magnums including the Cheytac and SnipeTac. The front etching band diameter is 0.373 and the rear driving band diameters are 0.375. The required barrel twist rate for stability with a muzzle velocity greater than 2,800 fps is 1:10.6. The bullet is machined from UNSC36000 brass. The advanced projectile design and controlled manufacturing tolerances advance the accuracy potential of these cartridges. Weight - 330 grains BC (calculated) - 0.941 Length - 2.000 Design velocity - 2,800-3,500 Material - UNSC36000 brass Sold in a packages of 50 at $65.00/box. Shipping via USPS Priorty Mail to the 50 states is included in the price. |
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Post by kaytod on Feb 22, 2013 21:44:35 GMT -5
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Post by pbslinger on Feb 23, 2013 2:43:43 GMT -5
I suspect Lee isn't making an SA cylinders for a while.
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Post by Lee Martin on Feb 23, 2013 8:44:00 GMT -5
Thanks Todd. I completely forgot about Lehigh. I need to order their 808 gr 50 cal so I'll get some 375's as well. -Lee www.singleactions.com"Building carpal tunnel one round at a time" |
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Post by Lee Martin on Feb 23, 2013 9:14:37 GMT -5
I suspect Lee isn't making an SA cylinders for a while. We're actually finishing another 327 Meteor tomorrow. But our focus will shift back to rifles for a while. In fact, I have some neat projects lined up and will definitely post progress on each. -Lee www.singleactions.com"Building carpal tunnel one round at a time" |
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