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Old 05-13-2008, 07:49   #88
Northalius
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Join Date: Jan 2008
Location: Virginia, U.S.
Posts: 984
Quote:
Originally Posted by GlockBaby View Post
JB:

I've looked at 10mm ammo for awhile now, and, it looks like you loose too much velocity for the bullet weight, once the bullets get over 180 grains. Browning originally wanted a 200 grain 45 ACP bullet, going something like 1000 fps, or more. Maybe he also saw the reduction in bullet speed not being compensated, or benefited from the increase in bullet weight.

DoubleTap 10mm
135gr JHP @ 1600fps - 11.0" / .70" frag nasty
155gr Gold Dot JHP @ 1475fps - 13.5" / .88"
165gr Gold Dot JHP @ 1400fps - 14.25" / 1.02"
165gr Golden Saber JHP @ 1425fps - 14.75" / .82"
180gr Golden Saber JHP @ 1330fps - 16.0" / .85"
180gr XTP @ 1350fps 17.25 / .77
180gr Gold Dot JHP @ 1300fps - 15.25" / .96"
200gr XTP @ 1250fps - 19.5" / .72"
230gr Equalizer @ 1040fps - 11.0" and 17.0" / .62" and .40"

In other words, if you look at ballistic tables long enough, and gello results, you sort of see points where, as much as I love bullet weight, the increase in weight doesn't result in much benefit, except higher recoil. There hits a point where you just need a bigger case, not higher pressure.

You sort of hit a wall, where the increased bullet weight requires a speed increase the case and powder can't provide, or, the bullet needs to have a thicker jacket to limit the expansion speed, or a harder core, or premium design.

I'm really not sure much is gained increasing bullet weight with DT ammo going from the above 180 grain bullets.

DoubleTap .45ACP
185gr Gold Dot JHP @ 1225fps - 12.75" / .82"
200gr Gold Dot JHP @ 1125fps - 14.25" / .88"
230gr Gold Dot JHP @ 1010fps - 15.25" / .95"

In 45 ACP, at least with Gold Dots, it seems pretty clear the 230 grain both expands more, and penetrates deeper. However,
With 45 Super max velocity for the 230's is about 1100 fps, and, 1200 fps for the 200's, and, I don't have gello results...It is possible to push the 185's to 1350 fps, and, they might well both penetrate, and expand more then at 1225,...

GB

Above are Buffalobore factory offerings in 45 Super.
Just to clarify: Checking the .45 ACP ballistics on the DT website, you'll see he uses a 5" 1911 to test his .45 ACP; whereas with the 10mm he uses a 4.6" Glock 20 stock barrel. So, to evenly compare the velocities and penetration / expansion, you'd have to test the 10mm with a 5" 1911 barrel against the DT .45 ACP results.
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