Speer .38 Spl 135gr Gold Dot +P in Vyse Ballistics Gel

[5pins]

Test Gun: S&W M442
Barrel length: 1 7/8 inches.
Ammunition: Speer .38 Spl 135gr Gold Dot +P (53925)
Test media: 10% Vyse Ballistics Gel
Distance: 10 feet.
Chronograph: Caldwell Ballistic Precision Chronograph G2.
Five shot velocity average: 848fps
BB Calibration: 4 inches.

https://general-cartridge.com/2022/0...allistics-gel/

[LockedBreech]

Nice work 5pins, thanks for doing this.

Even for Gold Dot, that's a picture-perfect performance for a .38 +P.

[WDR]

This is one of two JHP loads I'll carry in my snub, the other being RA38B. Good to see it performing well.

[5pins]

I put up the comparison test using the Knox gel today. Slightly different results between the two.

https://general-cartridge.com/2022/0...stics-testing/

[the Schwartz]

I put up the comparison test using the Knox gel today. Slightly different results between the two.

https://general-cartridge.com/2022/0...stics-testing/

I think that you've confirmed that the store-bought Knox (non-ordnance) gelatin is a very reasonable substitute for the VYSE ordnance gelatin. One thing is for sure though. It beats the Hell outta the Clear Ballistics Gel crap by a country mile.

Although your shear validation (of 9.525cm) for the store-bought Knox gelatin is just slightly over the maximum (correct shear validation range is 8.50cm ± 0.40cm), the minimum and maximum bullet expansion dimensions obtained in the Knox gelatin tests (0.57'' x 0.54'', 0.56'' x 0.55'', 0.57'' x 0.55'', 0.57'' x 0.55'') are practically identical to those obtained in the VYSE ordnance gelatin tests (0.56'' x 0.56'', 0.56'' x 0.55'', 0.57'' x 0.54'', 0.57'' x 0.56'') especially when it is borne in mind that even within the exact same manufacturing design there will be some degree of variance in terminal expansion. The fact that terminal expansion, which is driven by dynamic pressure which is a function of the gelatin's composition and physical properties, is effectively the same in both the Knox and VYSE test mediums confirms that they are dynamically similar, or in other words—you've just established that the store-bought Knox gelatin is a test medium equivalent to the VYSE ordnance gelatin.

As for your Knox gelatin being slightly out of specification, as I wrote in a prior thread—

Why not?

The Knox unflavored gelatin, being made of partially hydrolyzed collagen just like ordnance gelatin, should do just fine if it shear-validates correctly. By merely meeting that parameter, the Knox unflavored gelatin far surpasses the ability of the clear polymer stuff to correctly represent shear forces in soft tissues. If you really wanted to ''run the ball out'' on the use of it, perhaps an email to Knox (or the manufacturer of another gelatin source) could provide some guidance as to the bloom strength of their product.

As noted earlier in this thread, TNOutdoors9 seems to have achieved correct shear-validation with his use of the Knox unflavored gelatin although I do believe that he had to increase the concentration ever so slightly to get it to behave within specification. Even when using Type 250-A ordnance gelatin, it is common practice to slightly increase concentration if otherwise correctly prepared blocks fail to shear-validate correctly, so adjusting the concentration of the Knox unflavored gelatin is not an unreasonable practice.

Other than ensuring that your water temperature never exceeds 104°F, a very small increase (another 1%) in the amount of Knox gelatin powder in your next gelatin batch will probably bring your next Knox gelatin block into the correct range eliminating the need to perform the ''corrective math''. If you still find the need to pursue the math, let me know. l'd be happy to help. Hit me via PM if you want.

As far as foaming is concerned, mixing at the slowest possible speed is recommended to minimize the entrainment of air into the solution. Even then, foaming can occur. There are anti-foam agents that can alleviate the issue, but at some added expense.

Good job, 5pins.

[the Schwartz]

Too late to edit my post above, but if anyone is looking for the correct anti-surfactant chemical for reducing foam in water-based applications, it is dimethyl-polysiloxane which also more commonly known as dimethicone in dietetic applications.

[5pins]

I think that you've confirmed that the store-bought Knox (non-ordnance) gelatin is a very reasonable substitute for the VYSE ordnance gelatin. One thing is for sure though. It beats the Hell outta the Clear Ballistics Gel crap by a country mile.

Although your shear validation (of 9.525cm) for the store-bought Knox gelatin is just slightly over the maximum (correct shear validation range is 8.50cm ± 0.40cm), the minimum and maximum bullet expansion dimensions obtained in the Knox gelatin tests (0.57'' x 0.54'', 0.56'' x 0.55'', 0.57'' x 0.55'', 0.57'' x 0.55'') are practically identical to those obtained in the VYSE ordnance gelatin tests (0.56'' x 0.56'', 0.56'' x 0.55'', 0.57'' x 0.54'', 0.57'' x 0.56'') especially when it is borne in mind that even within the exact same manufacturing design there will be some degree of variance in terminal expansion. The fact that terminal expansion, which is driven by dynamic pressure which is a function of the gelatin's composition and physical properties, is effectively the same in both the Knox and VYSE test mediums confirms that they are dynamically similar, or in other words—you've just established that the store-bought Knox gelatin is a test medium equivalent to the VYSE ordnance gelatin.

As for your Knox gelatin being slightly out of specification, as I wrote in a prior thread—



Other than ensuring that your water temperature never exceeds 104°F, a very small increase (another 1%) in the amount of Knox gelatin powder in your next gelatin batch will probably bring your next Knox gelatin block into the correct range eliminating the need to perform the ''corrective math''. If you still find the need to pursue the math, let me know. l'd be happy to help. Hit me via PM if you want.

As far as foaming is concerned, mixing at the slowest possible speed is recommended to minimize the entrainment of air into the solution. Even then, foaming can occur. There are anti-foam agents that can alleviate the issue, but at some added expense.

Good job, 5pins.

Thanks for the math help offer I may take you up on it. I'm reading Duncan McPherson's book and I think I'm just going to have to sit down with a pen and paper so I can visualize it.

[the Schwartz]

Thanks for the math help offer I may take you up on it. I'm reading Duncan McPherson's book and I think I'm just going to have to sit down with a pen and paper so I can visualize it.

The equation is surprisingly simple to apply.

Pages 258 - 261 cover the process.

Besides the actual penetration depth of the BB and the recovered mass and diameter of the bullet, tables 10-2 and 10-3 are all that is needed.

For example, for your 135-grain JHP that expanded to an average diameter of 0.56'' in your test (BB penetration depth = 3.75'' or 9.525cm) and penetrated to a depth of 13.75'', the correction value is ≈ 0.72'' so you'd need to subtract that from the final penetration depth of your test bullet such that 13.75'' - 0.72'' = 13.03'' (corrected depth)

[4given]

Good Job! This is my go-to 38 Special round for 3" & 4" revolvers.