Lack of volicity change

[steepdiver]

I was out yesterday doing some load testing and ran into something I have never seen before or even heard of. So I am looking for some advice.

I am shooting a Savage 10 BA chambered in 308 WIN

The cases are LC 65 MATCH trimmed to 2.005"
Bullet is 175 SMK
powder is Varget
They have a OAL measured to the O-Give of 2.258" (This seats them .005" into the lands)
I shoot loads of 45.5, 45.2, 44.9, 44.6, and 44.3 grains

OK now that you have all of that here is the puzzle. All loads produced a measured muzzle velocity of 2758 average on the high side and 2752 average on the low side. Now I was pleased with 2 of the groups 7/32" and 11/32" (have a witness and photos if needed). Has anyone ever run into this problem of velocity not changing with charge at all. The only thought I have is it may be the seated into the lands.

 

[Turd in the Pool]

I was out yesterday doing some load testing and ran into something I have never seen before or even heard of. So I am looking for some advice.

I am shooting a Savage 10 BA chambered in 308 WIN

The cases are LC 65 MATCH trimmed to 2.005"
Bullet is 175 SMK
powder is Varget
They have a OAL measured to the O-Give of 2.258" (This seats them .005" into the lands)
I shoot loads of 45.5, 45.2, 44.9, 44.6, and 44.3 grains

OK now that you have all of that here is the puzzle. All loads produced a measured muzzle velocity of 2758 average on the high side and 2752 average on the low side. Now I was pleased with 2 of the groups 7/32" and 11/32" (have a witness and photos if needed). Has anyone ever run into this problem of velocity not changing with charge at all. The only thought I have is it may be the seated into the lands.

I'd take another rifle/load combo to check my chrono. A full grain has to change the vel.

 

[milo 2.0]

When the load gets to pressure stages, you can quit gaining velocity, I've even seen it drop. When it happens to me, I won't run the high velocity charge, back down some.

 

[ksthomas]

What Milo said. Seen it many times, and yes, it can actually cause a slight loss of velocity if you keep adding. Nature's way of telling you, that's all you're gonna get from that combination, and it's time to back it down.

 

[steepdiver]

What Milo said. Seen it many times, and yes, it can actually cause a slight loss of velocity if you keep adding. Nature's way of telling you, that's all you're gonna get from that combination, and it's time to back it down.

Thank you for the input. As i was not looking nor expecting this velocity there was no need to go any further. The range came froma ladder test to find the rifles node. this just happened to be the charge ranges in the node. So now that i know its somwhat normal and can proced with testing i will move on to see if jumping the bullets has an effect on the group sizes or velocity. Thanks again.

 

[Unknown]

When I was testing Varget in a TRG22 and a 24 inch barreled DPMS/LR308, I ended up with 43.5 grains giving the best performance in both rifles. I didn't want 2 different loads, so I took the load with the best "average" performance. My velocity showed a steady increase and I stopped testing at 44 grains. My velocity is 2667 FPS from the LR308, and 2640 from the TRG.

I find it interesting that diver's velocity stalled out below where I found optimum results for both rifles, even though his starting charge is well above where I stopped. The variables that would cause this would be of interest, but I suspect that it is simply individual rifle/chamber/throat differences.

 

[jasent]

Maybe your not getting enough neck tension. Could be not all your powder is burning because the bullet leaves the case to easily and can't build any more pressure than what your getting. What die are you using to resize? Have you noticed any unburned powder in your barrel? Have you measured unloaded neck and compared it to loaded neck?