Underwood 38 Special +P 158 grain Hi-tek, how are they doing it?

[rosewood]

How are they getting 1200+ with a 38 special and staying within SAAMI +P specs? Or are they way over pressure? They list it at 1250FPS and the chronograph is giving 1200+ out of a 4" barrel. Just over 1000 FPS is the most I have been able to find with any powder combination of published +P data.

https://youtu.be/xVVlDcsF_s0

Rosewood

[Piedmont]

There is no magic so my guess is they are overpressure. I won't shoot stuff like that in my guns, several of which aren't strong to begin with.

[Daekar]

There is no reason to push a 38spl that hard. If you want that performance, buy a 357. You're not doing yourself or your gun any favors by pretending a 38 is a 357, and Underwood should probably double-check their loading. Given how mild 357 loads are today compared to yesteryear, that's darn close to full power magnum speed in a factory cartridge.

[mnewcomb59]

CIP pressure for 38 special is higher than SAAMI 38+p. I would have to look it up but I think CIP is 21k PSI. Pull a round and weigh the charge. If it is around 6-6.5 grains it is likely in Unique burn range or if it is 10-12 grains it might be Accurate No. 9 to 2400 burn rate. For safe pressures I would expect to find 10-12 grains of slow powder to make those kinds of velocities.

[nannyhammer]

Don't ask me how I know but you can get close with Unique. I found out that there is a big difference between 5.2 grains and 5+2 grains on the scale when you have a rectal cranial inversion. If you look around you can find the old 38-44 loads that are pretty warm.

[gwpercle]

They use the data shown in the Speer #8 Loading Manual ...
Or the test barrel is a Universal Receiver ... no cylinder and no cylinder gap ...
Or they calculate using the new left math ... you know 2 +2 = 12

The 38-44 loads listed in Elmer Keith's 1936 reloading book ...160 gr. cast SWC , 13.5 grs 2400 loaded in Remington 38/44 cases w/ Remington primers ... no velocity is listed ...
But I bet it comes close !!!
Remember this was 1936 and the 357 magnum hadn't been invented ... the 38/44 load was the 38 Special +P of that era and Remington loaded 38/44 factory ammo in Remington cases headstamped 38/44 ... look in the book at the photo's !
Gary

[rosewood]

They use the data shown in the Speer #8 Loading Manual ...
Or the test barrel is a Universal Receiver ... no cylinder and no cylinder gap ...
Or they calculate using the new left math ... you know 2 +2 = 12



Well, the test by the utuber measured the MV and was getting over 1200 FPS from the 4" revolver. So it must be from the Speer #8 manual. :)

[Thumbcocker]

IIRC the old Super vel ammo used slightly undersized projectiles to get higher velocity.

[rosewood]

IIRC the old Super vel ammo used slightly undersized projectiles to get higher velocity.

I would have thought that would slow it down by allowing gas to escape around it. Interesting.

[lar45]

Quickload thinks that they are running close to 25kpsi to get over 1200fps with either Blue Dot or 2400.

[HWooldridge]

I would have thought that would slow it down by allowing gas to escape around it. Interesting.

Probably not that small. .355 pill down a .357 bore will still engage the rifling and seal good enough. Not sure you could detect blowby in a pistol length barrel. Now, a .425 jsp intended for the 44-40, but fired in a .430 44 mag barrel would likely leak.

[44MAG#1]

VIRGEL shows the same Defense Wound Mass for a 35 caliber SWC bullet at a velocity of 401 to 1596 fps so if it were me I would select no more than 750 fps. Fast recovery, low muzzle blast in close quarters and just as effective.

[justindad]

Doesn’t moly coating yield higher velocities at the same pressure?