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Weird data

Printed From: OpticsTalk by SWFA, Inc.
Category: Firearms, Bows, and Ammunition
Forum Name: Reloading & Ballistics
Forum Description: Anything to do with ammunition
URL: http://www.opticstalk.com/forum_posts.asp?TID=44386
Printed Date: January/18/2018 at 04:03


Topic: Weird data
Posted By: supertool73
Subject: Weird data
Date Posted: September/30/2017 at 18:13
On my 6.5 creed i chrono 2565 from 41.2 grains of h4350.

On my 300 wsm 2975 from 63 grains rl17.

Went to range today and shot them from 100 yards out to 800 yards. I used my ballistic calc to get data. Well it was way off at every distance. So i record the actual data and come home. I just couldnt figure out how things were so far off. Checked and checked my settings and i think everything is correct. So i start changing the velocity. When i get the creed to 2800 it is near exact all the way to 800 yards. No distance off by more than .25 moa.

I do the same with the 300 wsm and get it to 3200 and everything is right on out to 800 yards.

I just dont see how it is possible i could be getting those velocities. I womdered scopes, but two scopes off exactly the same. Two rifles off almost exactly the same.

What am i missing here?

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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."



Replies:
Posted By: supertool73
Date Posted: September/30/2017 at 18:15
Bullets 143 eldx
Barnes 180 ttsx

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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: Kickboxer
Date Posted: September/30/2017 at 18:26
I'd say a chronograph error…  looks like you are approximately the same value off… 235 fps on the 6.5 Creedmoor, 225fps on the 300WSM.  

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: supertool73
Date Posted: September/30/2017 at 18:28
But 2800 fps from my 20” creed. I dont see how that is possible.

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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: supertool73
Date Posted: September/30/2017 at 18:37
Also i have ran data in two calculators and get same results

-------------
Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: Kickboxer
Date Posted: September/30/2017 at 18:38
It is a mystery.  

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: Kickboxer
Date Posted: September/30/2017 at 19:00
I can't come up with a RECOMMENDED way you get to 2800 fps with a 20in barrel.  2635.  Doesn't say it can't be done.  

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: Urimaginaryfrnd
Date Posted: October/01/2017 at 16:44
Tail Wind ?  Devil

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"Always do the right thing, just because it is the right thing to do".
Bobby Paul Doherty
Texas Ranger


Posted By: supertool73
Date Posted: October/01/2017 at 17:46
There was really no wind that day.

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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: Kickboxer
Date Posted: October/01/2017 at 18:02
FM...

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: Lockjaw
Date Posted: October/02/2017 at 15:36
I wonder if its because of the BC of the bullets?? I am sure the ELD is up there. The ones I loaded in my 308 were LOOOOOOOOOOOONNNNNGGGGG!!! 

I have never shot a barnes. Wish I had a place I could shoot 800 yards, or better yet, a gun that would. 


Posted By: nralifer
Date Posted: December/05/2017 at 02:59
What happens if you lowered the BC of the bullets you fired and kept the velocity the same? Doubt the chronograph is off if you were not getting pressure signs on the brass.  You could also check the scope by doing a tall target test at 100 yds to see that the bullet impact corresponded with the change in scope dope.

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It is hard to fail, but it is worse never to have tried to succeed. TR


Posted By: anweis
Date Posted: December/05/2017 at 20:57
my creed shot 2830 fps with 123 gr bullet out of a 21" tube with 44 grains of H4350. I loaded up until the primers seemed like they wanted to blow out, then i reduced the charge by 1/2 grain.
Your velocity seems to be just fine as far as i can guess. Note: just a guess.
What i think may be the culprit is your formula or calculation.
Namely, you may have something wrong about BC, temperature, atmos pressure, etc


Posted By: nralifer
Date Posted: December/21/2017 at 04:38
Any resolution to the problem?

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It is hard to fail, but it is worse never to have tried to succeed. TR


Posted By: supertool73
Date Posted: December/21/2017 at 09:18
Nothing yet.  I am just using the data I get from shooting vs my ballistic program.  I have went over the settings dozens of times trying to see a issue and so far am blind to what I have done wrong. 

I have shot out to over 1000 yards several times with it now and the program shows the 2800ish fps. 

I have not spent much time with them since hunting season got over.  Been playing with my six5 instead as of late. 


-------------
Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: supertool73
Date Posted: December/21/2017 at 09:47
If I put the exact same data in my iSnipe app, my hornady app, and the online berger app I get 3 different results.

1000 yards with iSnipe 34.97moa  Hornady 37.6 and Berger 32.59 

And my actual data is 28.75ish MOA for 1000 yards

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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: billyburl2
Date Posted: January/01/2018 at 21:06
Jason, do you have a weather meter or are you using station pressure? If you don't have access to the actual barometric pressure it can really screw up your data.

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If it is tourist season, why can't we shoot them?


Posted By: nralifer
Date Posted: January/11/2018 at 05:02
The differences that you observe between actual and predicted elevation at 1000 yds are large (3.84MOA between you and Berger calculator).  Differences that large might happen if your scope turrets are not moving the reticle in accordance with the turret indicator or if you inadvertently used a G1 BC for a G7 BC. Since you checked your setting multiple times, the latter is not likely.  It may be the scope turret moving the elevation bar on the reticle more than indicated by the turret since 28.75 is rather flat shooting at 1000 yds for a bullet starting out at less than 2600 fps with a G1BC of 0.625 as advertised by Hornady. 

I use the Shooters Calculator and if I plug in 2565 fps for your 6.5 bullet with a 200 yd zero under standard conditions and with the 0.625 G1BC advertised by Hornady for the 143gELD-X I get 32.7 MOA elevation at 1000 yds.  If I increase the BC to 0.8 I get 28.83MOA elevation at a 1000 yds, only 0.08 MOA more than what you observe. The ELD-X is a good bullet but not that good.  The turret error would be about 13% greater movement of the elevation bar than indicated (3.84/28.75x100).

Don't know what length barrel you have but if I adjust the velocity to get to the 28.75 MOA elevation you observe at a 1000 yds, the MV would have to be 2715 which is close to MV that Hornady advertises for their precision hunter ammo from a 24" barrel.  What velocity were you expecting from the load you used?



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It is hard to fail, but it is worse never to have tried to succeed. TR


Posted By: supertool73
Date Posted: January/11/2018 at 09:15
I need to check my scope(s) for certain.  But the fact that both my Leupold scopes would be off the exact same amount seems strange.  Possible for sure and it may in fact be the case, but seems strange.  Velocity data, barrel length.  I was expecting about what I am getting.  I assumed around 2600 for the 6.5.  Actual was 2565, from 20 inch for the 6.5.  2975, and 23" for the 300 wsm

On a slightly different topic.  I bought some RL16 powder to try.  Just like 17 but very temp stable and has a copper fouling agent in it.  Excited to try it.  My buddy is using and getting a nice velocity increase over 4350 as well. 

I might stick my SS 5-20x on it as well to see how it fairs. 


-------------
Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: supertool73
Date Posted: January/11/2018 at 09:17
Originally posted by billyburl2 billyburl2 wrote:

Jason, do you have a weather meter or are you using station pressure? If you don't have access to the actual barometric pressure it can really screw up your data.


I have tried it both ways and it does not account for that much error.  At least alone.  It could be that combined with others factors though.

I just have not made time time yet to figure this stuff out.  When I finally do I will share my findings for sure. 


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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."



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