Power Gaps

[lizziedog1]

Many firearms can use cartridges of different power levels. Guns chambered in 357 magnum can shoot 38 Specials. 44 Specials can be used in 44 magnums, and so on.

I was looking at reloading data for these types of cartridges. There is usually a gap in powder charges in any given bullet weight between the magnum loads and the nonmagnum loads. Is there any safety concerns reloading the magnum cases with a powder charge that splits the difference betwen the two cases. It is a charge that is not listed for either round. It would be too high for one, and below starting for the other.

Lets say a certain powder charge for a specific bullet ends at 8 grains for the non magnum case, the same bullet and powder for the magnum case starts at 10 grains. Would reloading the magnum case with 9 grains cause any safety problems?

 

[jinxer3006]

I know that for SOME powders you need to be very careful about reducing charges too low. This is from the Hodgdon Reloading Data Center:

H110 and Winchester 296 loads should not be reduced more than 3%.

Reduce H110 and Winchester 296 loads 3% and work up from there. H110 and Winchester 296 if reduced too much will cause inconsistent ignition. In some cases it will lodge a bullet in the barrel, causing a hazardous situation (Barrel Obstruction). This may cause severe personal injury or death to users or bystanders. DO NOT REDUCE H110 LOADS BY MORE THAN 3%.

 

[Sam1911]

As long as you are sticking to published loading data, you will be fine. There may be some degree of a gap between the highest power .44 Spc. listed and the lowest power .44 Mag (as an example) with certain powders or types of bullet but you can find plenty of safe ways to bridge that gap.

For example, Hodgdon lists loads for a .44 Spc. that will get a 240 gr. bullet moving at nearly 950 fps. They list loads for the same bullet -- in the .44 Mag. data -- with loads down below 800 fps. Plenty of overlap there.

In fact, using Hodgon's powders and data alone, you could take a 240 gr. LSWC from just over 670 fps to nearly 1,400 fps in the same .44 Mag revolver!

 

[Walkalong]

It all depends, but basically yes, you can download the mag caliber to non mag levels using an appropriate powder in the right amounts.

 

[rcmodel]

+1

Pressure and velocity will be slightly less using the shorter cases starting load in longer Magnum cases due to less case capacity in the longer case.
However it should be perfectly safe.

Anything over the ".38 / .44 Special's" starting load is just another safe load in the Magnum case.

As jinxer3006 noted, the only exception might be with slow burning ball powders such as H-110/W-296.

rc

 

[roadliner]

Although I reload for the 44 special, I use light loads in magnum brass for my SRH when hunting small game. I've loaded as light as about 700-725 fps with a 240 lswc bullet. I've done the same with 357 brass. I actually have several hundred 38 special cases that I've never bothered to use since I just download the magnum brass. Beside the already mentioned W296/H110 warning, I remember years back there was a warning about extremely light red dot loads with .38 wadcutters. I don't know for sure if that danger was ever proven in the lab.

 

[altitude_19]

The danger of reduced loads is surprisingly simple: If the charge is so small in relation to the case, the odds go up that it will not have sufficient exposure to the primer flash to consistently ignite the propellant.
I once played a game of "how low can you go" with my 45 ACP and got them all the way down to about 390 FPS before I decided it was enough. As I dropped below the minimum charge, I noticed a drastic increase in Standard Deviation. So sometimes the propellant will be up against the primer, sometimes not. If it is sufficiently isolated from the primer flash, you have a squib.
I have heard THEORIES that a small enough charge burns so fast that it actually increased pressure, but have seen no lab data to confirm this is the case...I'm calling it a myth for now.