Cold bore accuracy

[bstomper]

My Winchester model 70 in 7mm rem mag is my dedicated hunting gun. It has the factory sporter barrel ( thinking of a rebarrel) on it and during load development the cold bore shot always seems t have a different impact point than the shots following it. I want it to be able to put the first cold bore shot exactly where I want it every time I pull the trigger on the first shot. After all isnt it the first shot that matters the most in a hunting situation. How would I go about doing load development for that? Do my load development as usual but let my barrel completely cool between each shot so that each shot is a cold bore shot?

 

[sierracharlie338]

Cold bore tracking is what you seek. The short of it is, every time you pull your rifle out at the range you need to track what is happening with that first shot and first shot only. Shoot groups after that. Is the barrel clean, dirty or fowled. Temp, distance etc. Maintain a record of your cold bore only shots and you will be able to track the repeatability of your cold bore shot with your equipment. Obviously this needs to be done once you have a final load worked out.

 

[Blancoalex]

Agree with sierracharlie above. I check my rifles couple times a year. Here is my main 2 a 300 Wby and 243 Win. Shot five minutes apart with same Crux can that I use for both. Seeing this brings a lot of confidence.

 

[Mrvmax]

Load development will be slow but once you have that selected the White Feather has a good method for zero.

https://americanshootingjournal.com/carlos-hathcock-method-of-sighting-in-a-rifle/amp/

 

[milo-2]

I just want to interject a couple things, like an above poster said, document the cold bore, do it 5 days in row if you can.
Cold bore used to be a concern of mine, even though today I am not a hunter, or really a group shooter. At one time, it seemed all my rifles shot 1/4 moa high, and about 1/4 moa right on a cold bore, I monitored this for awhile, thinking the muzzle brake was the culprit.
One day it dawned on me to warm up with a different rifle before logging a cold bore on a perceived issue. In my case, it was never the rifle imparting that much into the cold bore, it was me.
Today, I shoot some practice rds before I shoot groups or test loads, just ensures that I am settled in and up for the task.

 

[Plinker147]

Consistency is what the goal is. If the shots are way off after the barrel heats a little. Find out why it's moving and work to fix it. I personally wouldn't put up with a rifle that can't put 3 shots in a row under MOA

 

[elf]

What you say is pretty common, and usually caused by the first shot from a clean barrel. Most competition shooters have learned that it takes a shot or two for the barrel to "settle down". My competition 30BR takes 6 - 8 shots from a clean bore to settle down. Best advise is to put 1 or 2 shots thru barrel after cleaning and let it that way.

 

[65WSM]

One of the attributes of HBN coated bullets, is that the first shot is typically indistinguishable in a three shot group. You can document this with a target camera system. David Tubbs also has a You tube video describing this advantage to HBN coating. No naked bullets!

I also hunt with a 7mm Rem Mag Model 70 with factory barrel that I purchased used, pulled the barrel and had it nitrocarburized. I believe that the firing pin safety on these rifles is superior to trigger safeties for hunting. I have seen trigger safeties fail in below freezing weather.

 

[CoachChris]

On Erik Corrina's Patreon page he has a cleaning video with Thomas "Speedy" Gonzalez.
He addresses this. He recommends a good coating of Lock Ease.
It worked for one of my rifles
YMMV

 

[Radman]

My Winchester model 70 in 7mm rem mag is my dedicated hunting gun. It has the factory sporter barrel ( thinking of a rebarrel) on it and during load development the cold bore shot always seems t have a different impact point than the shots following it. I want it to be able to put the first cold bore shot exactly where I want it every time I pull the trigger on the first shot. After all isnt it the first shot that matters the most in a hunting situation. How would I go about doing load development for that? Do my load development as usual but let my barrel completely cool between each shot so that each shot is a cold bore shot?

Seen several rifles like this down through the years. Sometimes because of last-shot cleaning & then needing a fouling shot - sometimes not. With all respect just zero it for your first/cold shot if it's for hunting.

 

[bstomper]

What you say is pretty common, and usually caused by the first shot from a clean barrel. Most competition shooters have learned that it takes a shot or two for the barrel to "settle down". My competition 30BR takes 6 - 8 shots from a clean bore to settle down. Best advise is to put 1 or 2 shots thru barrel after cleaning and let it that way.

Ill have to make note of this because I do always clean my barrel after a shooting session.

 

[bstomper]

One of the attributes of HBN coated bullets, is that the first shot is typically indistinguishable in a three shot group. You can document this with a target camera system. David Tubbs also has a You tube video describing this advantage to HBN coating. No naked bullets!

I also hunt with a 7mm Rem Mag Model 70 with factory barrel that I purchased used, pulled the barrel and had it nitrocarburized. I believe that the firing pin safety on these rifles is superior to trigger safeties for hunting. I have seen trigger safeties fail in below freezing weather.

I like the safety on the model 70 also. But I have never used a safety on a gun in my life. If I'm not in position to take the shot and pull the trigger, there isn't a round in the chamber, or if I have to move to get a better position to shoot, I unlock the bolt. Just don't trust the safety on any rifle no matter how good it may be.

 

[bstomper]

Thanks for all the advice guys, i will definately be doing some not taking and get this figured out.

 

[MagnumManiac]

Often, you can eliminate the cold bore shot variance by tweaking action screw torque.
It is often caused by a not so stress free bedding job.
The other cause is a not so concentric fit between barrel and action.
I have only had one barrel that did this, it turned out the heat treating part of the stress relieving was not done correctly and the barrel walked once warm. Cryo fixed it, but cost a fair amount on top of what it already cost.
If the cold bore shot always hits a certain distance away from additional shots, then I would track that and keep that as the true POI and sight in that way.
Definitely try the action screw torque variance, do 65in/lbs on the front and 55in/lbs on the rear if a synthetic or drop those by 10in/lbs each on wood. Then change by going less 5in/lbs to 45/35 as a minimum. Also try equal amounts on each as well.

Cheers.