Disappointing results

[4dogs]

I loaded some 10 mm ammo today and had made a change to AA #9 powder to get a little snappier load. As reference, I'm using Hdy 155 gr. XTP bullets. Ultimately I loaded 15.5 gr of powder (max according to the powder mfg is 15.9 gr), COL of 1.25".

At the range, the new loads clocked a mean of 1195 fps. I shot 10 rounds, using the club's chrono that I've used for all my previous samples. The round should have clocked around 1370 fps and previous loads with a different powder are in that range (actually, the last sample had a mean of 1320 fps).

I suppose the answer is that I shouldn't have changed powder but trying something different hoping to improve is part of why we load our own.

Your comments are all welcome.

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[PhysicsGuy]

What was your previous powder?

I used primarily blue dot for 10mm loads (180gr)

 

[SAR1846]

Velocity is one of those metrics which is affected by a ton of different variables. Barrel length, OAL, crimp, temp, etc... even firearms with the same barrel length & chamber will get different results. I wouldn't worry much about meeting a specific velocity, but would spend my time working on the main goal = accuracy. Obviously, if you're working towards a power factor for matches, than that might be a main goal as well.

 

[4dogs]

What was your previous powder?

I used primarily blue dot for 10mm loads (180gr)

Accurate #7

Also, I have been shooting all through a G20sf with stock barrel. Will soon be swapping it for a longer Lone Wolf barrel,.

Which yields another question - one maybe true for a lot of reloading. The loading specs from Accurate give a max load with of 12.7 grains with the round I use. Hornady, on the other hand, gives a significantly higher (more than 14 grains) maximum for the same bullet. I've tried different powder loads, all with good results. The only problems I've had have been with Remington nickel plated brass splitting. My local reloading mastermind thought it might have been from putting too much flair in that stage of the process. Although we adjusted that, I also set all the Remington brass aside and have had no other problems.

 

[jib]

I would think AA#9 would do better with a heavier bullet. It could be you don't have adequate start pressure to get the powder to burn consistently ? What primer are you using ?