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.