Try Accurate Arms powder data way you will more speed with aa1680 powder no more pressure.The small pistol primers are not ment for the 357 max it is flirting with danger to do so.I use Winchester and CCI small rifle primers.You should be able to get close to 2000fps with aa1680 and a carbine length barrel no problem with small rifle primers.I like the Hornady 180 XTP best it was made for the 357 maxium.

I'm new to reloading, and was wondering what advantage the rifle primers have over the pistol primers?
Yesterday, I tested 19.3 grains of H4227 with the bullet seated at the second cannelure.
Very good groups! One 4 shot group at .65 ", and two other shots at .5" .
The overall group 6 shots = 1.68" at 50 yards. This round is showing some promise.
I'm not sure about increasing the charge anymore because the Hornaday data states that the max FPS for the 180 XTP is 1434. And based on load data 19.3 gives that from a 14" Contender, so I'm sure I'm pushing it over 1600fps with the 22 inch barrel NEF.
RV

Rifle primers are tougher and will withstand the 50,000 CUP that the .357 Max can go to. It IS stated to be a requirement for that reason. Clearly if you are loading to the old .38 Extra Long standard (i.e. 6 gr. Unique and a 150 gr. lead bullet) you won't have nearly the pressures. That's not what most do as that's not what the case was developed to do.



I don't know where you got that max velocity for the 180 gr. XTP 1434 fps is too exact. Are you confusing that with a velocity given in loading data? I know that some have pushed this bullet to 2300 fps muzzle velocity and it has held together. I personally doubt that is a wise move and I would prefer the 180 Speer FP for that use. Interestingly, the Speer works well when started at 2000 fps even from the .357 Max.



Lil'Gun will beat AA168O with some bullets and at lower pressure. I'm not pushing with H110 and I get 1970 fps from my 21" barrel. I'm certain that you could get 2100-2200 with the 180s maybe 2000 fps with the 200s and Lil'Gun or AA1680.



I will reiterate, you must use small RIFLE primers. A pierced primer at these pressures in the gun you are using can be a very bad thing indeed. There is NO benefit to using small pistol primers. The cost to you of buying a $20 brick of primers is NOTHING compared to your EYESIGHT! (I've seen a couple of instances of the failure of protective eyewear. A fine safety element, NOTHING is guaranteed!)

That FPS rate was in the box of .357 XPT's on a cigarette size piece of paper. Does anyone roll their own legal smokes anymore? I thought that sure was low. 357 magnums blow that rate out of the water.
RV