Santa Barbara Surplus Sucks!
Decided to buy a box and see what’s up with the very wide velocity variations reported.
Paid $3.25 for a 25 round box. The box is marked March 1983, and the cartridge head-stamps are SB-T 9C 82. Primers are sealed with Green lacquer. Cases show light corrosion beginning to form.
I weighed all 25 rounds and found the average weight to be 140.3 grains, with a low of 138.6, and a high of 141.5.
Cartridge overall length averaged .9556”, with a low of .944”, and a high of .966”. This is a huge difference (.020”) in OAL, and it appears reports of bullet set-back may be coming out of the box that way!
Next up, I selected the 3 lightest, 3 heaviest, and 4 mid-way in total weight, and pulled the bullets. Here are the results:
OAL Total weight Case Bullet Powder
.957” 138.6 gr. 45.4 gr. 87.7 gr. 5.4 gr.
.960” 139.3 gr. 45.8 gr. 88.0 gr. 5.4 gr.
.946” 139.8 gr. 46.2 gr. 88.2 gr. 5.5 gr.
.949” 140.0 gr. 47.5 gr. 87.1 gr. 5.3 gr.
.961” 140.1 gr. 47.3 gr. 87.5 gr. 5.4 gr.
.954” 140.4 gr. 47.1 gr. 87.8 gr. 5.3 gr.
.964” 140.4 gr. 46.3 gr. 88.6 gr. 5.4 gr.
.961” 140.7 gr. 47.6 gr. 87.7 gr. 5.5 gr.
.944” 141.2 gr. 48.1 gr. 87.6 gr. 5.3 gr.
.952” 141.6 gr. 48.0 gr. 88.1 gr. 5.3 gr.
Average:
.9548” 140.2 gr. 46.93 gr. 87.83 gr. 5.38 gr.
Difference, low - high:
.020” 2.9 gr. 2.7 gr. 1.5 gr. .02 gr.
Percent difference:
2% 2% 6% 2% 4%
Now none of this may seem too extreme, however it’s a lot more variation then you would ever find in most any other .380 ammo you care to check. For example, I weighed and measured 25 rounds of S&B ammo, and came up with a loaded cartridge weight variation of only 1.6 grains, and an OAL variation of only .004”.
Now, the odd part. While pulling the SB-T bullets with an inertia bullet pullet, I noticed some of them popped out with a light tap, and others required several hard blows. Bullets are sealed in the case with an asphalt sealer, however it appeared to be uniformly applied, and could not account for that much difference in neck tension.
Next, I measured all 10 pulled bullets and found they all measured .3535”, or 1 ½ thousandths Smaller then the established .380/9mm .355” bore size!
My observations:
1. SB-T is loaded with an average of 5.38 grains of powder. This is a very large charge, and would have be considered a relatively slow burning powder for the .380 cartridge in order to use that much. It would probably fall somewhere in the range of Alliant Herco or Blue Dot in burning rate.
2. Very doubtful you could expect to always get a complete burn in a very short barrel with powder this slow.
3. Powder appears to be changing color from gray to yellow, and may be in the early stages of decomposition. This is likely caused from improper storage at high temperature, and not from age. (Properly stored, 24 year old ammo should be as perfect as the day it was made.)
4. Case neck tension is very low, and even after resizing the cases, still was not as tight as it should have been. It is mostly dependent on the asphalt sealer to hold the bullet in place.
It could be the cause of the ammo being declared “surplus”!
5. Whether or not the under-size bullets were intentional, (to lower pressure) or by accident, is open to speculation. If it was intentional, you would assume they would have used under-sized loading dies to maintain proper case neck tension. But they didn’t!
This could also have caused it to be declared “surplus”!
6. Quality control of OAL, and weights of all components is perhaps the worst I have ever seen in over 40 years of reloading.
7. The wide velocity swings reported are probably caused by the under-size bullets allowing gas to leak past them in the bore. I feel confident some of the bullets bump up to fill the bore and get a good gas seal, and resulting high pressure & velocity, while others do not. And that results in gas leaking past the bullet, less pressure, and lower velocity on some of them.
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