Rifle is a 24 inch barreled M700 in 30-06.

I was playing with loads of 180 Corelocks for cheap practice/deer ammo.

H4350 showed the best promise, so I was working up to book max of 57.5 grains.

Got my first chronograph last week, so trying it out with the loads.

57.0 grains ran at 2680 +/- 15 fps, No pressure signs. Best accuracy.

57.5 grains ran from 2610-2672 fps (only five shots). All but 1 was very close to 2620. No pressure signs. Groups opend up a bit from the 57.0 grain samples.

Thinking I had mislabeled the rounds, I repeated the test with Nosler partitions I had loaded previously. I go essentially the same results.

So, more powder = less velocity

I assume I was not burning all the powder in the barrel? Is there something else that could be wrong with my loads (neck tension, flash hole, etc..)??

not always,but many times when your velocity goes down with more powder you have about reached a max. level,a bit more powder than that will give a big spike in speed or worse.

It is not likely that you have reached a max where the velocity is going down. Far more likely in my opinion, especially since you just started using the chronograph is that the first time, You may have had the chrony not completely flat which will make the distance between screens closer and velocities higher. Play around with it sometime and you'll find it takes very little to make a 100 fps change by accident. It's just a little thing you have to be very aware of, as you unfold it, then you end up moving it around several times to line it up with the target, etc. It also will change if the chrono is not lever, distance between screens is longer as you're shooting at an angle, therefore lower velocities. Setup is critical when the distance between screens is only a foot or so. Set it up very carefully and try it again and let me know what happens. Also bear in mind that if you're using a powder measure and 4350, it is very easy to have a half grain variation from shot to shot as it doesn't meter easily, so your .5 grain increase in powder charge is almost negligible, although it still shouldn't be 50-75 fps higher.

Seems like we all have to go thru a relearning process the first time we try a chronograph out.

Do hope you didn't get a sorry Chrony.
IF you did, do two things before you use it again.

Replace those wire's with dowel's, dime stick will make four pcs. Shoot a wire and it's wrecked.

Get a pcs of plastic, glass etc adn cover the face so unburnt powder dont' eat hole's thru the membrane face.

Neither are covered by their worse than none warranty.

Wish you well,

George

It's a decreasing returns point... if the powder is slow enough, you won't be burning it all, if it's quick, it's fixin to jump.

this is one of those "changes" I've mentioned before, where you add powder, it goes up fairly evenly, then CHANGES either up or down. Everyone has had this happen to them, if they do serious dev work.

switch powders if you don't like the 2680 laod?
jeffe

quote:

So, more powder = less velocity???

Quite possible and not strange at all. But your progression only included 2 samples...57.0 and then 57.5...not enough to determine useful info. You need to load 5 or 6 loads, each increasing by .5 grain. You should see a proportionate increase in speed with each increase in powder. Known as statistical analysis. Your combination of components obviously topped out at the 57.0 mark. Working up with IMR4350 could yield different results. As could a different primer, or seating depth.

Sometimes muzzle blast, particularly from slower powders, will alter the readings.
Step back another 10 feet and try again.
Good luck!