Cold bore shot question

WKR

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Do you count your cold bore shot muzzle velocity when calculating your extreme spread and standard deviation?
Why or why not?
 

rayporter

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i always delete it for my target rifles because i can fire a fouling shot or shots. and it may go in the group but it is frequently several fps off.

for my hunting rifles a cold bore is all that counts. fire one shot every day for a few days to get a real result.
 

wyosam

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Target or varmint rifle? Probably not. Hunting rifle? The ES I care about is the cold bore shot over a number of range trips (the more, the better). Always watch POI and velocity of the cold bore shot if you can for hunting rifles. Doesn’t matter if the next 9 are in one hole with an ES of 5, if the first one was wide and makes the ES 50.


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1stSgt M

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For hunting its all about the first round, not often you get a second or third chance. I'll wait till the barrel cools completely before my next test load. Like wyosam said watch the POI and velocity...
 

Raghornklr

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Do you count your cold bore shot muzzle velocity when calculating your extreme spread and standard deviation?
Why or why not?
Thank you for this, I’ve been wondering the same thing. Was shooting a new gun this weekend trying to figure it out before sending in for the cds dial.
2980 1st shot and the next 3 dropped to 2960.
Let it cool then shot 2982.
I’m going to go with cold bore numbers for the dial.
 
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Cold cleaned bore will give a different velocity/POI, but a cold fouled bore should be the same as the rest of the shots, yes? I.e. as long as you aren't cleaning the bore between range sessions, the only reason the first shot wouldn't fall in your usual 10-shot grouping is if you aren't as ready as a shooter? So for load development, be sure not to include a clean/oily bore shot in your calculations, but as long as you dry fire a bit to get yourself ready, no reason to exclude it? Not a pro or bench rest competitor, just a hunter who loves shooting, which is why I've posed these as questions rather than hard claims. I'm not new to shooting, but newer to reloading, so I'm still figuring a few things out. But I'm finding that doing a lot of dry firing, and not cleaning the bore at all, I don't seem to have "cold bore shots" any more, and no more vertical change from the first shot compared against subsequent shots. I've been paying close attention my last dozen visits to the range, and noticing the first shot is the same as the rest.
 
OP
WKR

WKR

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Cold cleaned bore will give a different velocity/POI, but a cold fouled bore should be the same as the rest of the shots, yes? I.e. as long as you aren't cleaning the bore between range sessions, the only reason the first shot wouldn't fall in your usual 10-shot grouping is if you aren't as ready as a shooter? So for load development, be sure not to include a clean/oily bore shot in your calculations, but as long as you dry fire a bit to get yourself ready, no reason to exclude it? Not a pro or bench rest competitor, just a hunter who loves shooting, which is why I've posed these as questions rather than hard claims. I'm not new to shooting, but newer to reloading, so I'm still figuring a few things out. But I'm finding that doing a lot of dry firing, and not cleaning the bore at all, I don't seem to have "cold bore shots" any more, and no more vertical change from the first shot compared against subsequent shots. I've been paying close attention my last dozen visits to the range, and noticing the first shot is the same as the rest.
Not in my experience, the differential factor being the heat of the barrel. Even my fouled cold bore shots have a substantially different muzzle velocity than a my subsequent hot barrel shots.
 

Trippy

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Not in my experience, the differential factor being the heat of the barrel. Even my fouled cold bore shots have a substantially different muzzle velocity than a my subsequent hot barrel shots.
Depends on the rifle, load, environment, etc. perhaps?

In 30 degree weather I did a 10 shot string for speed on a 7 RM. ES 14, SD 5. Bit of a mild load for a 7 RM but the first and last shots were within 4 fps of each other. The barrel was a little warmer than I normally let it get.

I always leave a barrel fouled going into a hunting season due to the POI change. A clean barrel has always had more of a POI change than barrel temp on that rifle as well as my 300 WM although I do wait 2-3 minutes between shots with them, longer in the warmer temps. I suppose if you fire 10 shots one after another there could be a bigger difference in POI and speed, among other issues.
 

Rich M

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If you are looking at the consistency of the load, it might be better to disregard the cold bore data as it will be slower.

If you are looking for a hunting load, might behoove to shoot only cold bore shots and do the math on those alone.

I notice a definite velocity and POI change from cold bore. Velocity increases as the barrel expands with the heat.
 

1stSgt M

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For hunting it's all about the cold bore shot right? So being dialed in on your POI is the more important than velocity fluctuations???
 

bsnedeker

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I'm a hunter, not a PRS guy. When I'm working up loads I honestly don't even really care about ES and SD. I do collect them as data points, but only after I've figured out the load I'm going to hunt with. I shoot three shot groups that start with cold bore and I put the next two shots downrange fairly quickly as this is the most realistic hunting scenario in my experience. I look for barrel harmonics by figuring out charge weights that give me same/similar POI's to give me some room for error.

Whatever load in the harmonic range gives me the tightest groups is the load I go with. After that I start shooting through the chrono in order to work up my dope chart.
 

Vandy321

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What Rich said...

I'm far from an expert...but I would delete it if i was checking ES/SD for a specific load for a target rifle, as most comps will allow you practice time or fowlers and a warm bbl ES/SD would be more applicable over the duration of the event.

If it is a pure hunting rifle, i'd also want to know the cold bore ES/SD...completely cool the bbl between each shot so the entire shot group was cold bore. Also, gives you some solid data for your cold bore zero that way as well.
 

1stSgt M

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I'm a hunter, not a PRS guy. When I'm working up loads I honestly don't even really care about ES and SD. I do collect them as data points, but only after I've figured out the load I'm going to hunt with. I shoot three shot groups that start with cold bore and I put the next two shots downrange fairly quickly as this is the most realistic hunting scenario in my experience. I look for barrel harmonics by figuring out charge weights that give me same/similar POI's to give me some room for error.

Whatever load in the harmonic range gives me the tightest groups is the load I go with. After that I start shooting through the chrono in order to work up my dope chart.
I have spent some time doing LR but I appreciate your approach makes sense..
 

ghostmoney

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Do you count your cold bore shot muzzle velocity when calculating your extreme spread and standard deviation?
Why or why not?

Yes because if the cold bore shot is different than the next 3 shots then I want to tweak my load so that it isnt.

Cold bore and clean bore are different though. I dont hunt or check velocity on a clean bore. After load development I will clean and then shoot until POI matches my zero. My 260 takes 4 shots to foul enough to stabilize and after that my velocities are consistent.
 
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