I did a previous test with Speer .38 spl +P 135 gr Gold Dot from my S&W 638 and it had less than stellar results. This load is supposed to be one of the few recommended loads for a short barreled .38 revolver and it did not perform as expected. I thought it might have something to do with the colder temperatures the day we did the testing so I redid the test. I left the revolver and ammo in the refrigerator overnight and kept it in the cooler on the way out, then fired a couple shots with it cold and one with it warm. I also fired a shot from a 4" GP-100. All shots were through four layers of denim and impact velocities are noted.
I’ve seen other videos where the results looked quite good.
The results of your tests, if they were done properly and are comparable with tests done by others, raises another issue.
Who knows what we get when buying different lots of any expanding rounds? We don’t know if the manufacturer changes the lead alloy, jacket thickness etc. from lot to lot. Only testing like yours will prove adequate expansion, velocity etc. of any lot of ammunition.
That’s why a SWC is fine with me from my 2 in revolver. I’m not expecting any expansion from that bullet.
I am most definitely an amateur. I’d like to see more professional tests done. I do believe that this last test at least indicates that the ammunition may be marginal and sensitive to temperature change. A user on another forum had the idea of dunking the revolver in ice water between each shot, which would allow me to do more shots with a relatively controlled temperature. Then I could fire the same number of shots after the revolver and ammunition has had a chance to warm up.
Why did you use 4 layers of denim? Is this some sort of industry standard you located ? What was the temperature of the gelatin? I know that when we did testing at work the ammunition vendor frequently checked the temperature of the test medium. We completed testing during the summer months and he was concerned that the gelatin was within a certain temperature threshold. I shot the 135g +P through one layer of cotton t-shirt covered by one layer of denim and the projectile expanded like it should.
This is a bit off topic, but entertaining. There was some gelatin left over and we shot it with my 45-70 rolling block rifle. I shot the gelatin with a 305g SP hunting cartridge and the effect the round had on the gelatin and table were devastating. It split the 2" thick wood table top and the gelatin bounced several feet away from the table. When we inspected the table you could see where chunks of wood were blown off the bottom of the table top. It would be my choice for a hunting cartridge if I were hunting buffalo or bear.
Four layers of denim is an IWBA protocol for handgun testing intended to represent heavy clothing that can sometimes pack a hollow point bullet and prevent expansion. I have no doubt that these bullets would have expanded in bare gelatin.
The temperature of the gelatin should be about 39 degrees, F. There’s no doubt that on a hot day the gelatin will heat up and yield inaccurate results. I don’t have a way to measure the temperature of the blocks. I keep them in a refrigerator with a measured temperature of 39 degrees until just before I leave and I keep them in a cooler until just before I use them. I believe the important part is to calibrate with a .177 cal BB immediately before testing and that’s what I do.
I am confused. The GD 135gr +p has remained on the best seller list for some time, but this is the 3rd time I’ve seen tests of it where it failed to expand.
If it works, it’s great, but I am beginning to wonder if it works consistently enough to be the goto ammo for my j-frame. The recoil is not bad, but it is certainly harder on an airweight than the 110gr Hornady Critical Defense, 110gr Corbon DPX or 148gr wadcutter round.
The wadcutter round won’t expand, but offers low recoil, a .38 caliber cookie cutter profile and has the mass to penetrate, but I don’t know if it has enough velocity to penetrate, particularly in the winter when it may have to penetrate heavy clothing first.
When I carry my j-frame as a primary, I load it with GD’s, but when I carry it as a backup, possibly to be given to my spouse in an emergency, I load it with standard pressure CD or wadcutters. Easier for her to hit with.
I’m beginning to wonder if I should just leave the 110gr or 148gr wadcutters in it all the time.
Folks that are shooting a lot of the round, carrying it for a living, and knowingly going in harms way with it aren’t changing. Nor is the round coming off the recommended list.
I’d not sweat it.
I’m not a professional so you shouldn’t put too much weight in my tests. That said, I’d like to see a professional test this load at lower temperature. My test isn’t conclusive by any means but to me it’s enough to warrant further examination. I think most ballistic testing is done at 70 degrees.
I can’t think of a job where a person would knowingly go in harm’s way with just a 2" J frame.
Folks that are shooting a lot of the round, carrying it for a living, and knowingly going in harms way with it aren’t changing. Nor is the round coming off the recommended list.
I’d not sweat it.
All things that don’t help a bullet expand.
You missed the point. The folks that track and assess why bullets expand and fail are among those I mention.
You should just say, “I like the bullet and I’m not going to switch, even after seeing this test”. There is no reason to make things up, like knowing what complete strangers “in the know” are thinking or doing.
I load the same bullet in my 357, though reloaded to just under the speed of sound from a 2" barrel. I’m not switching either.
I can’t think of a job where a person would knowingly go in harm’s way with just a 2" J frame.
Wise beyond your years 
I shot the round through one layer of denim and a t-shirt. The round opened up beautifully. It makes you wonder if 4 layers of denim plugs up the hollow point and if you will ever have to shoot through 4 layers of denim in a defensive situation.
I enjoy reading tests like this.
Thank you Mr. Wiggin.
Thanks man, appreciate the assist. I’ll try harder. :dance3:
Looks pretty simple to me. Colder temps caused a drop in velocity below the window of optimal performance for the round when fired from a 2" barrel. If you are in this situation, might want to look at a different round. If not, why worry? You’re .38 won’t kill sharks 10 feet under-water, either…that’s why they make a spear gun, but that doesn’t mean it won’t work on a car-jacker. Tool matches job = success.
Good test, and very enlightening, thank-you, OP!
When I shoot rifles from a warm shelter at targets posted out in single digit temperatures, I do not see much change in the point of impact at 100 yards compared to shooting in warm weather. When my rifle and ammunition are exposed to cold temperatures for a period of time before shooting, I will see a change in the point of impact indicative of lower velocities due to the temperature change. This is why I have a below 35 degree zero and an above 35 degree zero in my log books.
Were the revolver and ammunition exposed to the cold for a period of time or drawn from a warm holster immediately prior to shooting into the ballistic gelatin during your test? You have to wonder if drawing a firearm from a warm inside the pants or pocket holster would make a difference.
We are talking about a defensive pistol and not a precision rifle, but I am still curious about the handgun/ammunition temperature.
The revolver and ammo was kept in the cooler until immediately before shooting. Each shot warmed up the cylinder and caused slightly higher velocity.
I think you’re right that carrying on the body would keep the ammo warm enough to function correctly. The problem is that my 638 has a good chance of riding in my or my wife’s jacket pocket, her purse or a glove box. She’s pregnant right now and can’t wear a belt.