I am reloading for my J frame S&W in 38 special.I have alot of small rifle primers and I was wondering if I can use small rifle primers to reload my 38 special rounds.

I would try them first. Prime a couple dozen cases to be sure you have enough hammer energy to provide reliable ignition; often there isn't. If there are no problems there, then reduce your regular load by 1/2 grain, and load away. The 1/2 gr reduction is to allow for the increased energy of the rifle primer over a pistol primer, and still get approximately the same velocity. The best-case scenario would be to chronograph them side-by-side, then adjust the powder charge so the velocities are identical.

You might get away with it...Rifle Primers are harder than Pistol Primers. You might get by shooting .38 Specials in a Chompson Contender.
I shoot Squid loads in .22 Hornet and .223 Remmington. I have had to go to Pistol Primers to get consistant ignition when shoot 4.1 grains of UNIQUE in my .22 Hornet.

Yotecaller,
The rifle primers have more power.
I just read a chart of energy and different primers, but I can't remember where.
Anyway, but experiments, I know the a wspm in .7 gr of powder more powerful than a wsp primer.

So if you reduced your load 1.5 gr and worked up, you should find the exact same load that worked.

If you are just worried about blowing you gun up, my expeimence is that j frame 38 specials can get a loose cylinder rotaion with a couple grains more than 357 mag, so there is lots of safety margin in those pistols. Big corperations would not be selling +P+ 38 special ammo if there were not an ocean of safety margin.

Thanks for the replies.

Yote - Actually the answer is "Yes." I've done it.

The problem is the small rifle primer cup is thicker/tougher than the cup used for small pistol. As a result, many pistols won't strike them hard enough for consistant ignition.

Also, the SRP are hotter than SPP so this could increase the ignition and burning rate of your loads some.

I have loaded a lot of 38 with SRP and never had a problem. However, the majority of it was shot in a .357 mag rifle by Marlin. I'm guessing I've actually run 200 rds of this stuff thru 38 and 357 ammo, also without a problem.

Now, do I think it's a good practice? Not really.

Frankly, what I would do if I were in your shoes is TRADE some of your SRP to someone who has a lot of SPP. I've done that too and everyone is happy.

It may be possible, but I'd avoid it, as the cup is too tough for most pistols and the primers are usually a bit taller and you may not be able to seat them flush with the bottom of the case head.

Maz - You are correct about the cup being a fraction taller and another reason this isn't the BEST of ideas, even though it will work in most cases.

I have found myself from time to time strangely blessed with an overstock of one kind of primer or another. They are never hard to trade with shooting buddies with a similar problem and a surplus of what YOU want.

I say again.......just trade them!