Jacketed vs. cast performance

[Chas.]

If I'm loading a 350gr. cast with certain load of powder/charge/primer, and I decide to use a 350gr jacketed bullet instead with the same powder/charge/primer combo, what should I expect in velocity difference, as well as pressure differences?

I ask this because sometimes I can find published loads for jacketed but not for the same weight cast that I want to load.

[Badnews Bob]

From what I've read and been tuaght you should never use cast info with jacketed bullets, If i understand this right jackets have more drag in the barrell creating higher pressures therfore unsafe with cast load info. But you can use cast with jacket info starting safe and working up of course.

I'd shure check close before I lit any off.

[jhalcott]

  With that little bit of information, it is hard to tell WHAT might happen. The bullet weight suggests a large bore gun. A like charge of powder COULD raise pressure several thousand pounds by going to a jacketed bullet. It MIGHT be enough to damage the gun, shooter OR bystanders. IF on the other hand , your load is a slow one , you COULD have a bullet lodged in the barrel because there wasn;t ENOUGH pressure to shove it out the muzzle! If you can not find info for the bullet /powder combo, contact the  powder maker or bullet maker for help.  Many powders are NOT suited to jacketed bullet use in rifles.

[Bigeasy]

Generally a jacketed bullet will raise pressures over the same load using a lead bullet.  Solids (Barnes X) can raise pressures even higher.

Forums like this are great for discussions about bullet performance, accuracy, favorite powders, etc.  But always refer to an up to date loading manual when deciding on a new load to try.

Larry

[LaOtto222]

You did not state what case you are shooting. Lyman's reloading manual is an excellent source of information on cast bullets of all calibers and weights. Generally, you can use jacketed bullet data for cast and be safe. Pressures will be less and velocities higher - generally. You always need to work your loads up. You have to be careful about achieving high velocities with cast bullets. Depending on the cast alloy being used, if they are gas checked or not, throat condition, cylinder alignment, etc you could range any where from 1200 fps to over 2400 fps and not get leading in your barrel. Soft lead bullets should be kept under 1000 fps and most probably 800 fps to be sure you do not get leading. If you purchase your bullets, in some cases, you can get data off of their web site or you can contact them for data. You must be loading a fairly big caliber if you are using 350 grain bullets. Are you loading for a hand gun or a rifle? You really did not give us much to go on. Good Shooting to you and Good Luck.

[Chas.]

Thanks to all for their responses.

I didn't give specific information because I was more interested in the principals involved in loading jacketed vs. cast, rather than any specific load. 

It could be my .44 or my 45-70, but I'm assuming the principal should be the same.  I just didn't know the principal. 

From what I glean, everything else remaining constant, a jacketed bullet will generally produce higher pressures and lower velocity than a cast bullet of the same weight.

BTW, I NEVER load to max - on anything.

[stimpylu32]

Chas

The basic rule is that cast bullets will have less drag or resistance going down the barrel so less pressure is needed to move said bullet , this is with all other things being equal .

However with a cast bullet into the lands and a jacketed bullet .050 off the lands , the cast load will require more pressure to move the bullet . Even though the overall pressure may be lower in this cast load, , the pressure curve will be steeper and reach MAX pressure much sooner than the Jacketed load .

See , its as clear as mud .  but yes ou have the basic idea .

stimpy