I posted this yesterday on 24hrcampfire. Thought I post it here to see if any more ideas come up. Thanks.

"I shot my first reloads tonight. I'll admit to being a little nervous because I didn't really have someone watching over my shoulder while I was doing this. Just asked alot of questions both here and elsewhere and read alot. I guess I did okay as I'm still here in one piece. Just a quick question. As I was working up the scale in powder charge I noticed that the velocity kind of peaked and regardless of the next higher charge was in the same ball park or lower in some cases. Why is this?
Forgive me if the answer is staring me in the face as I just got home and haven't dwelled/researched it yet. Powder was RL-22 and 225gr BT out of my 358STA with a 24" barrel. Is it that I have reached as much as the powder/barrel length combo will yield? Could it be the Chrono and lower light of evening? Any help is appreciated."

You can reach a point where additional powder does increase peak pressure, but does not increase muzzle velocity. It could be that you've reached that point. My 308 reaches that point with AA2520 well below the listed maximum load.

Lighting conditions do influence chronographs. Mine drops 50 fps as the sun starts to go behind a cloud. My rule is to chronograph only while the sun is well up, and I can see distinct shadows.

Without additional testing, it is hard to tell which, if either of these effects you are seeing.

I agree, further testing will commence next week. I'll start at my max velocity load and work up again in .3 increments. This should narrow down where the sweet spot is and see if I can repeat yesterday's results.

I was shooting the Hodgdon 38 Super load for LIL'GUN, and I overloaded it and the recoil went down.

I wrote to Hodgdon and they wrote back, "Of course, the efficiency goes down."

You passed the point in charge weight increase into the zone of not just diminishing returns, but the zone of "no return". What happens is that part of your powder charge becomes just an additional projectile that the powder which did burn completely has to drive out of the barrel along with the bullet. Therefore, there is less energy available to drive just the bullet, and bullet muzzle velocity actually drops! It is the same effect as if you were firing a heavier bullet. This effect is even more pronounced in heavily overloaded black powder cartridges/muzzleloaders due to the relatively low temperatures and pressures at which BP arms operate!

[ 07-03-2003, 15:41: Message edited by: eldeguello ]

1894
I can see how you may have misinterpreted my last comments. Chasing velocity was not my main concern. I was mainly looking for pressure signs to know where the limit is for my rifle. Then I will work slowly to find the most accurate load.

eldeguello
Makes sense. I still would like to see if the lighting had anything to do with it but I'm fairly certain your idea is correct.

More testing to follow.
Thanks.

I have a problem 264WM,while working up a loads,three loads shot about the same velocity.They were a grain apart with N-560.This time I believed the chrony,when the targets were layed on top of each other,the walking holes lined prefectly. .I think I was at barrel break-in point.

[ 07-07-2003, 02:49: Message edited by: downwindtracker2 ]

ScottinPA: It would be wise to listen to 1894. What I would do if I was you is to come down at least 10% in powder charge from the point where you didn't notice a velocity increase. Start all over again, and work UP a load.

Sometimes there are no pressure signs one can easily notice, until it is too late.

Ray

I'm all for keeping it safe, but reducing 10% from 91.5 grains puts me below the starting load. Doesn't make much sense does it? I'm not arguing with you just wondering why go so low?
The more I think about eldeguello's idea, the more it makes sense. Perhaps the barrel is the limiting factor before the pressure. Which would explain both the lesser velocity and the lack of pressure signs.
I've prepped the brass and am ready to prime and load but am not in so much of a hurry to do this half-cocked. Probably won't get to go to the range til next weekend anyhow.

Thanks.

You can tell if you are reaching the powder limits by firing at dusk. Have someone stand safely to the side and behind a little and fire two rounds each of successively more powder and watch the muzzle flame. You will notice a marked increase when you reach the overpowder point.
I didn't see where you mentioned a primer. Sometimes a cool primer ( CCI ) and low bullet tension & a relatively light bullet will not burn efficiently. If not now using - Try Federal 215 Magnum primers - drop back your powder charge - and work back up slowly.

[ 07-10-2003, 04:34: Message edited by: Old & Slow ]

You are that the "flatspot" of the expansion curve. If you get an increase is speed, it will be SUDDEN, along with a huge increase in preasure.

i like to find this spot, if possible, and load there, as texas weather is unpredictiable, other than HOT.

jeffe