Same weight, different size bullet question.

[stanws6]

I've been loading 4.8 grs. of Titegroup for my 158 gr. LSWC (bullet on the right) for my 357 guns. I just bought a box of 158 gr. bullets that are a different profile.(bullet on left).Because less bullet will be in the case do I need to add a little more, a little less, or the same amount of powder? Thanks

 

[stanws6]

I've been loading 4.8 grs. of Titegroup for my 158 gr. LSWC (bullet on the right) for my 357 guns. I just bought a box of 158 gr. bullets that are a different profile.(bullet on left).Because less bullet will be in the case do I need to add a little more, a little less, or the same amount of powder? Thanks

 

[WR Moore]

From a peak pressure standpoint you might be able to increase the load slightly. However, this is a really techinical issue, without a heck of a lot of application in the real world-unless you're loading at the ragged edge. You are better off staying with the current load.

 

[OKFC05]

Without a chronograph, you can't tell.
Internal ballistics are not just more complicated than you think, they are more complicated than you can imagine.

 

[musicmanbass]

I agree with the above posters. Leave the load alone, unless you are under max published loads and all pressure signs are OK. If there is room for more and you want a change go ahead and tinker, but I doubt you'll see much of a difference between the two given the same charge.

 

[Jellybean]

I'd leave it the same too, well actually I'd probably reduce it a little first just to be safe. There are other factors involved in the equation with bearing surface being one of them.

 

[musicmanbass]

Good point. Since I posted, I was also thinking about the hardness of the alloy. I'm not a bullet caster, but I did actually spend two hours at a Holiday Inn Express this morning! Some of you more experienced guys, do you find that a hard vs soft alloy has much effect on pressure/velocity? What about lube?

 

[OKFC05]

Originally posted by musicmanbass:
Good point. Some of you more experienced guys, do you find that a hard vs soft alloy has much effect on pressure/velocity? What about lube?

Compared to bullet size and sealing ability, everything else is secondary.
Guessing is fun but pointless. Shooting over a chronograph and checking accuracy tell the story.

 

[Snapping Twig]

Good looking boolit!

 

[pownal55]

if it is a commercial product the manufacturer should be able to provide load data. if they are from an unknown maker it would be wise to work up loads starting on the low end.

 

[Skip Sackett]

If I was the one casting them and knew my alloy, I would shoot several over the chronograph with the same weight of powder, and work up from there. Of course that flies in the face of what I tell others. "Change any component, work the load back up." Better safe than sorry.

Internal ballistics being what they are, for the most part, aren't going to suddenly change because you switched bullets. If you take the same bullet and put less in the case the pressure is going to go down if it isn't already hitting an obstruction. The bearing surface is nearly the same on both, no advantage there. Are they the same hardness? Are they the same size? There are many factors. Each one has a part in the equation.

 

[stanws6]

Thanks for the advice guys. Yes they are from the same manufacturer and the hardness and size are identical. Skip, I'll give them a call before I load any. Thanks