Point of Diminishing Returns?

[Black Jaque Janaviac]

Has anyone witnessed the Point of Diminishing Returns with smokeless powder?   I know it's a common idea in the black powder world, but since smokeless is progressive, I wasn't sure if it would be witnessed within the realm of safe pressures.

However, while chronographing some loads with paper patched bullets I think I noticed the PODR using Lil' Gun in a .357 rifle.

Over a full grain increase of Lil' Gun from 16.9 grains to 18 grains gave an increase in average velocity of less than 100 fps.  That's using a 125 grain paper patched bullet.  Mean velocity went from 1996fps to 2084fps.

I'm new to reloading, is this unusual?

[The Shrink]

Black Jack

From my readings, not from experience, it's a common occurance.  It's a function of the load, the internal ballistics of the case, and the chamber/throat of the rifle.  With some cases it used to be that there was no PDR, e.g the "way overbore" Whetherby's, 25-06, etc., but new slower powders have change even that.  

Each load and rifle will be different.  Welcome to reloading!

Wayne

[Arco Nudo]

More to be concerned with, I think, is that adding a little more powder can raise the pressures a lot.  As far as diminishing returns go, when developing my .270 load adding 1 grain of powder from 59 to 60 grains raised the velocity by about 150fps.  That's very significant at those velocities. 60 was the maximum.

[Dand]

Donlt know about the diminishing returns but if anybody is using Lil Gun they should check the Hodgdon Website regardinga recall on certain lots.

See:  PRODUCT RECALL - Lot #103080221 of Hodgdon’s LIL’ GUN -

PRODUCT RECALL - Lot #103080221 of Hodgdon’s LIL’ GUN - More Information Here

[Dand]

Guess I messed up inserting the link to Hodgdon's LilGun Powder recall site I'll try again   http://www.hodgdon.com/news/lilgunrecall.php

hope this helps

[Black Jaque Janaviac]

Arco,

That 1 grain increase represents a smaller increase when the doses are 59 to 60 grains.

But going from 17 to 18 grains is a bigger percentage.

And 150 fps would be a significant velocity increase in my book too.  Although it could be past the PODR (some people mistake the PODR as the point of negligible returns).

I am aware that pressures may/will continue to increase even if velocities do not.  I am staying under the max at all times.  Plus there is the "forgiveness" of having a newly made Model '92 lever action, and paper patched bullets (which generally make for less pressures).

[Black Jaque Janaviac]

Re: Hodgdon recall

My powder is from a different lot #.  So far it's been just the one lot # that has been recalled.