Using Small Magnum Pistol Primers in .38spl Gun

[Scragbait]

I have an older S&W M14 that I want to make target loads for. My recipe would be 4.0g of Unique with a 150grain cast SWC. This load is below the listed maximum. I have small pistol primers (Winchester) but the box says they are for magnum loads. The question is this: if I use these primers for .38spl loads in this gun, do I risk excessive pressure levels and possible damage? Are small magnum primers much more potent then regular primers? I also have a box of large pistol primers, also Winchester, but it says that they are for both magnum and standard loads and that has me thinking there might not be a big difference.

Thanks for any clarification you can offer.

 

[Cerdan]

You're right in thinking there isn't that big a difference. If you're the cautious type, you'll want to back down a bit on your powder charge.

 

[tjhaile]

Your load is fairly conservative, so you probably wouldn't have any issues with the magnum primers causing excess pressure. If you were trying to develop a maximum load, I would advise backing off and redoing your load development. That said, I would make a small test batch with the magnum primers to check for hard extraction or unusually flat primers before I made a whole bunch.

I have loaded up .38 Special with magnum pistol primers with no ill effect when I bought some by mistake.