Forums46
Topics537,936
Posts9,730,868
Members87,051
|
Most Online25,604 Feb 12th, 2024
|
|
|
SD of 29 and velocity all over the place?
#5926140
09/13/15 01:10 PM
|
Joined: Oct 2009
Posts: 12,220
wp75169
OP
THF Celebrity
|
OP
THF Celebrity
Joined: Oct 2009
Posts: 12,220 |
I ran my first 5 rounds through a chronograph yesterday to get my speed. The minimum and max were over 100 feet apart and the SD was 29. Average speed was 2577. This was also the first 5 rounds after cleaning the barrel so they were fouling rounds. I'm hoping this was just because of the cleaning/fouling because I am fairly confident that's the most consistent loads I can make. The gun shot good in my opinion. Later in the day I dialed wrong and missed 3 in a row at 600 yards so we drove down to see where I was hitting. The results would lead me to believe the speed leveled out. Here is my miss around shot 35ish for the day at 600.
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926177
09/13/15 01:43 PM
|
Joined: Nov 2007
Posts: 9,520
RiverRider
THF Trophy Hunter
|
THF Trophy Hunter
Joined: Nov 2007
Posts: 9,520 |
It's pretty obvious to me that your barrel needed to be fouled before it would settle down. And I'd say it settled down very nicely!
"Arguing with you always makes me thirsty." -Augustus McRae
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926203
09/13/15 02:14 PM
|
Joined: Dec 2008
Posts: 41,171
J.G.
THF Celebrity
|
THF Celebrity
Joined: Dec 2008
Posts: 41,171 |
What cartridge? Brass, primer, powder, bullet? Virgin brass?
800 Yard Steel Range Precision Rifle Instruction Memberships and Classes Available
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: J.G.]
#5926215
09/13/15 02:27 PM
|
Joined: Oct 2009
Posts: 12,220
wp75169
OP
THF Celebrity
|
OP
THF Celebrity
Joined: Oct 2009
Posts: 12,220 |
What cartridge? Brass, primer, powder, bullet? Virgin brass? 7-08, nosler, Remington 9.5, varget 39.8, 162 Amax, once fired FL sized.
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926224
09/13/15 02:32 PM
|
Joined: Dec 2008
Posts: 41,171
J.G.
THF Celebrity
|
THF Celebrity
Joined: Dec 2008
Posts: 41,171 |
It obviously started shooting once it got fouled, no surprise there.
Did you chronograph the shots after it was fouled or only on the beginning rounds? Your powder charge and bullet weight ae the same load as my 7-08.
800 Yard Steel Range Precision Rifle Instruction Memberships and Classes Available
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926236
09/13/15 02:39 PM
|
Joined: Oct 2009
Posts: 12,220
wp75169
OP
THF Celebrity
|
OP
THF Celebrity
Joined: Oct 2009
Posts: 12,220 |
Unfortunately I did not check any after it got fouled. There was several people shooting and the clamp on chronograph cause a POI change so it would have been a time and bullet consumer. As far as same load as yours if I remember correctly it's the same obermyer 5R barrel.
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926272
09/13/15 03:05 PM
|
Joined: Dec 2008
Posts: 41,171
J.G.
THF Celebrity
|
THF Celebrity
Joined: Dec 2008
Posts: 41,171 |
I believe they are the same barrel. I cut mine down to 20" and it always wears a suppresor.
I bet if you chronoed 5 rounds next trip out the numbers will look better.
800 Yard Steel Range Precision Rifle Instruction Memberships and Classes Available
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926310
09/13/15 03:45 PM
|
Joined: Mar 2012
Posts: 3,809
Cleric
Extreme Tracker
|
Extreme Tracker
Joined: Mar 2012
Posts: 3,809 |
I am having trouble with your math....
assuming an average of 2577, spread of 100 i can't get a stand dev below 35... and thats at ideal mathematical conidtions
Shot 1: 2577 Shot 2: 2627 (Avg +50) Shot 3: 2527 (Avg-50) Shot 4: 2578 (Avg +1) Shot 5: 2577 (Avg -1)
This would mean that the min/max were perfectly centered and the other two shots were within 1 fps
Do you have your actual 5 numbers?
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5926389
09/13/15 04:43 PM
|
Joined: Oct 2009
Posts: 12,220
wp75169
OP
THF Celebrity
|
OP
THF Celebrity
Joined: Oct 2009
Posts: 12,220 |
Nope. Just read the numbers and went with the average. It's not my math at all but that of the chronograph. I did not write down each speed. I do know one was in the 24xx and one was 26xx. Hence my statement over 100 ft. I may have shot more than 5 rounds and could explain the math. I was generalizing on the 5 rounds. I should have said 5 ish. Two people there are members here and one of them owns the magneto I was using. Maybe they can chime in with a better memory or the actual #s off the graph.
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5927604
09/14/15 12:21 PM
|
Joined: Sep 2009
Posts: 18,950
ChadTRG42
THF Celebrity
|
THF Celebrity
Joined: Sep 2009
Posts: 18,950 |
Remember my thread on cleaning and fouling shots? Your high ES numbers are from the cleaning and such. With a 1.5" group at 600 yards, just keep shooting it, you're fine.
|
|
|
Re: SD of 29 and velocity all over the place?
[Re: wp75169]
#5927971
09/14/15 04:41 PM
|
Joined: Dec 2014
Posts: 525
6.5x47Lapua
Tracker
|
Tracker
Joined: Dec 2014
Posts: 525 |
Another reason to leave the chronograph at home where it belongs. Hits and down range results are all that matter.
|
|
|
Moderated by bigbob_ftw, CCBIRDDOGMAN, Chickenman, Derek, DeRico, Duck_Hunter, hetman, jeh7mmmag, JustWingem, kmon11, kry226, kwrhuntinglab, Payne, pertnear, rifleman, sig226fan (Rguns.com), Superduty, TreeBass, txcornhusker
|