quote:

Originally posted by Andy:

PENETRATION OF FMJ RN BULLETS IN 375, 416, AND 458 CALIBER RIFLES AT STANDARD AND ENHANCED VELOCITY AND ROTATIONAL VELOCITY.

C 2001 Andy Tillman

Boards Caliber Bullet Velocity Twist Shots/Comment

458 x 404 (Similar to 460 GA).

71 1/2 458 x 404 500 FMJ 2,367 fps 1-10 One to two more boards than 1-14 twist which had slightly higher velocity.

71 1/2 458 x 404 500 FMJ 2,367 fps 1-10

48 458 x 404 450 GSFN 2,450 fps? 1-12 Perfectly straight bullet path.

46 458 x 404 500 FMJ 2,334 1-10 Hit left edge. Exited side of stop-box. Tipped at 40 boards (13 more than 1-14 twist). Penetrated 10 boards more than 1-14 twist. Threw wood 30 feet!

28 458 x 404 500 Barnes X 2,334 1-10 Unstable. Expanded and turned 180 degrees. Fully sideways at 23 boards, traveled base forward until 28 th. Climbing (upward) wound profile like 5.45 x 39mm.

450 Ackley

70 1/2 450 Ackley 500 FMJ 2,400 1-14 1-2 boards less penetration than 1-10 twist.

69 1/2 450 Ackley 500 FMJ 2,400 1-14

36 450 Ackley 500 FMJ 2,400 1-14 Exited side of stop-box. Tipped at 27th, fully sideways @ 31 boards. Ten boards less penetration than 1-10 twist.

458 Winchester (BRNO 602 with 25 inch barrel).

62 Simulated 458 Winchester 2,030 1-10 (Down-loaded 458 x 404). Penetrated 3-4 more boards than standard twist.

59 458 Winchester 500 FMJ 2,021 1-14 Circa 1980 Remington/FMJ

58 458 Winchester 500 FMJ 2,105 1-14 Federal Premium/FMJ

39 ½ 458 Winchester 450 GSFN 2,050 1-12 Simulated 458

23 458 Winchester 510 RNSP 2,105 1-14 Expanded. Federal Premium.

21 458 Winchester 510 RNSP 2,021 1-14 Expanded. Circa 1980 Remington.

416 x 375 Improved (Similar to 416 Remington or Hoffman but with 1-10 twist).

71 416 X 375 Imp 410 Kynoch FMJ 2,400 1-12 Three shots. Very consistent performer. Kynoch is copper clad steel jacket like Hornady.

375 Improved (Similar to 375 Weatherby or 375 JRS), 22 ½ inch barrel.

71 375 IMP 300 FMJ 2,791 1-8

70 375 IMP 300 FMJ 2,791 1-8

50 375 Improved 300 FMJ 2,791 1-8 Exited side of stop-box. 13 more boards than standard twist that exited.

375 H & H (22 inch barrel)

65 375 H & H 300 FMJ 2,570 1-8 Penetrated 4 more boards than standard twist.

61 375 H & H 300 FMJ 2,570 1-12 Twice

37 375 H & H 300 FMJ 2,570 1-12 Exited side of stop-box.

NOTES:

Stop-box made from 12 x 12 inch square sheets of ¾ inch thick pine spaced ¾ inch apart.

Range, 25 yards

All FMJ bullets were copper clad steel jacketed Hornady unless noted otherwise. The Kynoch had a slightly more rounded meplat than the Hornady.

QUICK ANALYSIS:

A faster than normal rate of twist in both 375 and 458 caliber rifles at both standard and “improved†velocity levels resulted in 3-4 more pine planks being penetrated than at standard 1-14 or 1-12 rates of twist.

Rotational velocity was not as important as increased velocity. The 458 wildcats (2,400 fps) penetrated 10-12 more boards than the standard 458 Winchester. The 375 improved (2,800 fps) penetrated 6 more boards than the 375 H & H.

A very high rate of twist (1-8) resulted in a penetration gain of 4 more boards over a standard 1-12 twist in the standard velocity 375 H & H.

Rotational velocity of greater than 1-10 twist may be beneficial when using monometal bullets of high SD. These very long (1.6 inch) bullets may also benefit from careful design, keeping the center of gravity exactly the same as its center of form.

There does not appear to be such a thing as a “magic†velocity threshold of 2,400 fps as some observers have suggested. The 375 improved at 2,800 fps penetrated 9-10 more boards than at 2,570 fps.

No increase in penetration was noted using contemporary versus vintage 458 Winchester ammo. When loaded with the same 500 gr Hornady FMJ bullets, circa 1980 Remington 458 Winchester ammo actually penetrated one more board than higher velocity Federal premium ammo loaded in 2001.

Most bullets could be de-stabilized by an edge hit on the 12 x 12 inch boards, or an overlapping hit on previous shots.

The quicker twist bullets were somewhat more consistent than slower twist but not enough shots were made to verify this with absolute certainty.

When FMJ bullets did exit the side of the stop box, the quicker twist did so 10-13 boards later than the standard twist.

A 458 Winchester could have the same rotational velocity as a 450 Ackley just by using a 1-12 twist.

ROTATIONAL VELOCITIES TESTED:

1-14 @ 2,021 fps = 1,717 revolutions per second (rps).
1-14 @ 2,105 fps = 1,789 rps.
1-14 @ 2,400 fps = 2,040 rps
1-12 @ 2,050 fps = 2,050 rps
1-12 @ 2,400 fps = 2,400 rps.
1-12 @ 2,450 fps = 2450 rps
1-12 @ 2,570 fps = 2,570 rps.
1-8 @ 2,570 fps = 3,855 rps.
1-8 @ 2,800 fps = 4,200 rps.

quote:

Originally posted by RIP:
Norbert says that three meters of water will stop most anything.

I used the 5 gallon buckets to catch three bullets and I caught the bullet of a .404 Jeffery .423/380 grain North Fork FP solid in the lid of the ninth bucket, laid end to end on the ground. The bullet was not deformed except rifling marks on the shank.

A .423/380 grain North Fork soft dented the bottom of the third bucket but pretty well exploded the first two buckets, perfect mushroom and about 95% weight retention.

MV was just over 2500 fps for both of the above.

Whatever water containers, 10 to 12 feet of water ought to stop any sporting rifle soft or solid.

Don't know about 50 BMG, 20mm, or 30mm depleted uranium.???

quote:

Originally posted by ASS_CLOWN:
Ron,

3 meters of water won't stop a 50 BMG! I know that for certain.

ASS_CLOWN

quote:

Originally posted by Minkman:
Just wanted to show my Son how bullets change shape on impact.

How many water filled, 55 gallon, plastic drums, layed end to end?

Using .243 Winchester, .338WM, and .458 Lott.

How does it change if solids are used?

Thanks

Jerry

__________________________

John H.

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