Expansion Testing

The following is a writeup by Blackbelt ammunition that loads our bullets in their commercial offerings and have done extensive testing, writeups and videos.


To view the gelatin testing videos of the first three types of ammunition – 380 ACP, 9mm & 38 Special, go to   Gelatin Testing | Blackbelt Ammunition | Reading | 19606

There will be more videos of our gel testing posted in the very near future.

We usually use Starline brass for our newly manufactured ammunition. However, we do offer some remanufactured ammo, preferring to use Remington once-fired brass that has been cleaned.

All loads in a particular caliber, either remanufactured or newly manufactured, are the same.


380 ACP – We use GT Bullets 88 grain hollow point loaded to 1,000 feet/ second in a standard length  barrel of 3 inches or more.

The average weight of these bullets is 87.9 grains. The retained weight of the captured bullet is 86.1 for a score of 98%. That means only 2% of the bullet’s mass was lost on impact.

The bullet is swaged to .355 inch upon exiting the muzzle of the handgun. The average expansion of the bullet was .520 inch, with an increase in the diameter of 46%.

To sum up, the 380 ACP 88 grain bullet, after exiting a 2.7 inch barrel at nearly 1,000 feet/ second and striking the gelatin as seen in the video above, it expanded 46% to .52” and retained 98% of its weight.

Did someone say that 380 bullets don’t expand? Ours do.


9mm Parabellum – Here we use the GT Bullets 130 grain HP. We have clocked this load at 1,200 feet/ second in some handguns, and over 1,450 in a Kel-Tec carbine. Very accurate, very effective.

In the gel test video above, this bullet below exited a 4” barrel at over 1,150 feet / second.  The average unfired bullet weight is actually 129.3 grains. Retained weight for the above fired bullet is 127.6 grains for a score of 98.7%.

As for expansion: the average diameter in the picture is .652 inch. That is an 83.6% increase in expansion.

For comparison, the factory jacketed bullet next to it (the name starts with a V) did extremely well. Its retained weight is 123.8 grains yielding a retained weight percentage of 99%.

Expansion: average diameter .613, yielding 72.6% expansion increase. Pretty good.


38 Special -  We load the 145 grain HP from G T Bullets to around 900 feet per second out of the 4 inch barrel of my grandfather’s very old officer’s model Colt revolver. My 3 inch barreled S & W is just as fast.

Results: Retained weight - 145 grains – 100% weight retention; Expansion – average diameter .586” -expansion - 64% increase.


357 Magnum – We have been using GT Bullets 165 grain HP and for good reason.

The average weight of the unfired bullets was 159.7 grains. The retained weight of the fired bullet on the right in this picture is 159.0 or 99.6%.

As far as expansion is concerned, the average diameter of this fired bullet is .684 inch, which yields a 91.4% increased expansion.

It is performance like this that earns the 357 Magnum its top rated spot as a self-defense cartridge.

There is also a jacketed hollow point bullet that we fired into the gelatin. The 158 grain name brand hollow point retained 100% of its initial weight, with virtually no expansion. These things happen.

These 4 loads above that use G T Bullets are my favorites as far as carry ammunition is concerned. I have been recommending these loads to family and friends for the past 4 years. That is when I became aware of G T Bullets. It’s simple - they just work. What more can you ask for?


40 S & W -  We recommend and load G T Bullets 180 grain HP for this caliber at approximately 1,050 feet per second (actual measured velocity was 1,066 ft/ sec).  This load has given us exceptional accuracy in a Glock & a S & W 610.

No pictures yet – but check out the 10 mm.


10 mm – Here again, we recommend G T Bullets 180 grain hollow point, loaded to over 1,200 feet/ second. This is a great, all purpose load for the 10mm.

The expanded bullet on the left is a GT Bullet 180 grain. The retained weight is 180.7 grains – 100%. Expansion was an average of .732 inch, yielding an 81.5% increase.

The factory loaded jacketed hollow point on the right has a retained weight of 179 grains yielding 99.4%. The expanded diameter of the factory HP was .559 inch on average, yielding an increase of 39.8%. Not to bad I suppose.


41 Magnum – We have 2 loads to choose from here. To say that these loads are outstanding would be a huge understatement. Let’s look.

  1. G T Bullets 215 grain RNHP at 1,200 feet per second from my snubby 2 ¾” barreled S & W.

The average measured weight of the unfired bullets is 211.2 grains, the recovered bullet weighed 209.1 grains, yielding a score of 99%.

Expansion: The average diameter of the fired bullet is ,684 inch – 66.8% increase.

This is a fantastic performance; good for general purposes, hunting, things go bump in the night. Great short-barreled performer.

But wait, there’s more.

  1. G T Bullet 250 grain Wide Hollow Point. This bullet exited the muzzle of my 2 ¾” barreled S & W at around 1,100 feet/ second. We were staggered by its performance.


The retained weight: 247.3 grains – 98.9%

Expansion: Average fired diameter - .801 inch  - 95.4% increase.

I am not making this up. If you like this great, under-rated cartridge, this just might be the best load ever for it.


44 Special – Our 44 Special ammunition is loaded with G T Bullets 255 grain round nose hollow point. It is loaded to a moderate 800 feet per second in my 2 ¾ & 3 inch barreled revolvers.

The fired bullet has a retained weight of 246.3 grains, the unfired are 255 grains. That yields 96%. To look at in another way, the bullet only lost 4% of its mass as it slammed into the gel block.

Expansion: The fired bullet has expanded to an average diameter of .720 inch, yielding 67.9% increase in diameter. Great performance for a 120 year old cartridge.


45 ACP. Speaking of oldies but goodies, the next cartridge is 113 years young. It has never fallen out of favor. There are probably more 45 ACP handguns out there now than ever before.

We use the 215 grain hollow point from G T Bullets, loaded up to over 950 feet per second. This bullet feeds flawlessly and is very, very accurate.

The retained weight of the fired bullet is 211.5 grains. An unfired bullet weight is 215.5 grains. The weight retention is 98.1%.

Expansion: The average expanded diameter of the bullet is .638 inch, yielding an increase of 41.1%


45 Colt – Arguably my favorite caliber. If there is ever a cartridge that screams to be fed a diet of cast projectiles, this is it. Accepted by the U.S. Army in 1873, we have had 150 years to figure out how to get the most pout of this round. We recommend for general purposes the 225 LSWC hollow point made by G T Bullets. It is accurate. A velocity of 1,000 feet per second is easy. These loads here were close to 1,100 out of a 7 ½ inch barrel. Standard pressure only. This is a very good performer. You will note we were having so much fun, we fired a couple of bullets.

Weight: The average weight of the unfired bullets is 226.8 grains. The average weight of the fired bullets is 217.4 grains, yielding 95.9%.

Expansion: The average expanded diameter of both bullets is .805 inches, yielding an increase of 78.2%.

G T Bullets makes great bullets. They are accurate, consistent and do exactly what they are supposed to do.

We needed these qualities in order to make the ultimate in self-defense ammunition.

If you want Blackbelt ammunition that is not listed here, please contact Blackbelt Ammunition directly at blackbeltammunition@gmail.com.

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