Question on 10% Ordinance Gelatin Calibration

After years of testing Clear Ballistics gel, I have recently taken the plunge into trying my hand at real 10% ordinance gel.

I've picked up some gelatin from Walmart (the great value brand) and mixed it according to the FBI specs to get 10%. I let it sit in my fridge for 6 days, transported it to the range in a cooler with ice packs, set it up and shot a .177 BB over a chronograph at 606 fps. Unfortunately, it penetrated 4" which is a little deeper than the maximum 3.74" that calibrated gel is suppose to be at. I still shot it with HP ammo and recorded my results, but I wonder how close my results actually are.

My questions for those in the know: Is there a simple math formula to help me adjust my results to get more accurate data? Is there other over the counter gelatin that has the same bloom as true Knox or Vyse gelatin (I couldn't find the bloom for the Great Value brand)? Other tips to consider?

Thanks in advance.

Yes, there is a formula to adjust the calibration. @the Schwartz can tell you about it. The store bought gelatin in not the same as 250A ordnance gelatin. There is a formula to convert to as well. When I get home later, I will find it and post it. The most coat effective way is to buy from WinCrest foods. This is an actual 250A bloom gel and works much better than the store - bought stuff.

https://wincrestbulkfoods.com/unflav...in-10-lb-case/

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Originally Posted by CZ Man

After years of testing Clear Ballistics gel, I have recently taken the plunge into trying my hand at real 10% ordinance gel.

I've picked up some gelatin from Walmart (the great value brand) and mixed it according to the FBI specs to get 10%. I let it sit in my fridge for 6 days, transported it to the range in a cooler with ice packs, set it up and shot a .177 BB over a chronograph at 606 fps. Unfortunately, it penetrated 4" which is a little deeper than the maximum 3.74" that calibrated gel is suppose to be at. I still shot it with HP ammo and recorded my results, but I wonder how close my results actually are.

My questions for those in the know: Is there a simple math formula to help me adjust my results to get more accurate data? Is there other over the counter gelatin that has the same bloom as true Knox or Vyse gelatin (I couldn't find the bloom for the Great Value brand)? Other tips to consider?

Thanks in advance.

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Yes, there a simple mathematical formula that allows for the correction of non-standard ordnance gelatin. The equation is found in MacPherson's book, Bullet Penetration. Out of respect for McPherson's published works, I will not publish his equation here (understandably a sensitive subject), but, if you do need further assistance, please feel free to contact me via PM.

In order to correct the penetration depths in the 10% ordnance gelatin block in which the BB penetrated to a depth of 4.00'' (10.16cm), you'll need to subtract 1.66 inches from the final penetration depth of the test projectile(s). Slight adjustments in gelatin concentration are an acceptable practice; they are commonly employed in respected labs. In order to decrease penetration by 4/10ths of an inch (on average), you'll need to increase the gelatin fraction by 1%. In the future, should you wish to avoid the need to mathematically 'correct' penetration depths, you should be able to bring your test blocks to the correct (slightly higher) viscosity by increasing the fraction of gelatin powder in your test blocks to 11% by weight.

Regardless of the brand of gelatin, if it shear-validates correctly (a process for ensuring that the low velocity drag regime is properly represented), test results are valid.

Thanks for the replies 5pins and Schwartz. It's been interesting working with ordinance gelatin despite the hassle to get it 'just right'. I'll play around with the concentration with the cheap over the counter stuff, and look into other brand options. The adventure continues...

This website has the conversion formula for the gelatin.
https://www.goodfoodgourmet.com/inst...omment-page-1/


Store bought gel is 225 bloom. In order to bring it up to the 250 bloom gel, the conversion would look like this for a two bound block.


"250 (bloom strength in the recipe) – 225 (bloom strength on hand) ÷ 250 (bloom strength in the recipe) x by 32 (or whatever the amount of gelatin is required in the recipe) = Amount needed to add to the recipe to achieve the right strength."

That should be 3.2 additional ounces.

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Originally Posted by 5pins

This website has the conversion formula for the gelatin.
https://www.goodfoodgourmet.com/inst...omment-page-1/


Store bought gel is 225 bloom. In order to bring it up to the 250 bloom gel, the conversion would look like this for a two bound block.


"250 (bloom strength in the recipe) – 225 (bloom strength on hand) ÷ 250 (bloom strength in the recipe) x by 32 (or whatever the amount of gelatin is required in the recipe) = Amount needed to add to the recipe to achieve the right strength."

That should be 3.2 additional ounces.

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That is very helpful! I've still got several packages of the store bought Great Value brand. Glad I don't have to just guess at how much more to add for my next batch.
By the way, I noticed your website general-cartridge .com is no longer available. Did it become too much of a hassle to keep it going? If so too bad! I enjoyed reading your test results.

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Originally Posted by CZ Man

That is very helpful! I've still got several packages of the store bought Great Value brand. Glad I don't have to just guess at how much more to add for my next batch.
By the way, I noticed your website general-cartridge .com is no longer available. Did it become too much of a hassle to keep it going? If so too bad! I enjoyed reading your test results.

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Yea, my domain and hosting costs were coming up, and it was becoming more of a hassle.