velocity loss question

[vanwhyjr]

Hello everyone,

Does anyone have an idea how much velocity I would lose in the first 15 feet? I was working up a load for my 284 this weekend and we had an Ohler Chrony set up at 15 feet.

I was up to 55 grains of H4831sc pushing a Berger 180gr Hybrid and only recording 2750fps. With no signs of pressure at all. The vertical for the groups was only like .25" but I was expecting a little more speed. I'm just not sure how much it slows down in that first 15 feet.

Thanks for any advise.
George V

 

[dmoran]

4 to 8-fps

Put 5-yrds (15-ft) and your particulars into a ballistic program. Then subtract that figure from your chrono data, will be pretty close, give or take a fps or two.
Donovan

 

[vanwhyjr]

4 to 8-fps

Put 5-yrds (15-ft) and your particulars into a ballistic program. Then subtract that figure from your chrono data, will be pretty close, give or take a fps or two.
Donovan

Thanks Donovan.

That's what i was thinking of doing. Just wanted to see if anyone had any other thoughts.

 

[KT]

George,
Is this a brand new Barrel? If so how many rounds on the barrel? Sometimes it takes up to 200 rounds for a barrel to settle in and the velocity to come all the way up. IF NOT see below.

If the barrel has at least 200 rounds on it you need to keep going up on your powder charge. (You should be one more node up)

KT

 

[vanwhyjr]

George,
Is this a brand new Barrel? If so how many rounds on the barrel? Sometimes it takes up to 200 rounds for a barrel to settle in and the velocity to come all the way up. IF NOT see below.

If the barrel has at least 200 rounds on it you need to keep going up on your powder charge. (You should be one more node up)

KT

Yes Keith, It's a brand new Brux 31". Those number are with 29 rounds on it. I have a MR match Sat. that should put another 70 through it. I will recheck MV after that I guess.

George

 

[KT]

Yes Keith, It's a brand new Brux 31". Those number are with 29 rounds on it. I have a MR match Sat. that should put another 70 through it. I will recheck MV after that I guess.

George

You should definitely see your MV jump up. Typically I don't even do load development until I have at least 100 rounds through it. Let me know what it jumps to after the match is complete.


KT

 

[vanwhyjr]

You should definitely see your MV jump up. Typically I don't even do load development until I have at least 100 rounds through it. Let me know what it jumps to after the match is complete.


KT

Will do.