Cold Barrel Shot, 3" High

[Bowhunter60]

Hey Guys,

I loaded up 20 rounds of .308Win using the following recipe.

• Brass - Lapua
• Primer - WLR
• Powder - TAC 46.1g (Min Load)
• Bullet - Barnes 130g TTSX
• MV - 3013

Rifle:

• Rifle - Thompson Center Dimension
• Caliber - .308 Win
• Barrel - 22"
• Twist - 1 in 12

I was quite surprised to find my cold barrel shots printing 3" high. Follow up shots were good. I'm zeroing for 200 yds, target at 100 yards. My shots should be 1.5" high at 100. I gave it 20 min between my initial 3 shots. The shot again. Exact same results.


So, my question for the reloading ballistics gurus. WHY?

 

[TimeOnTarget]

Not familiar with the TC but is the barrel free floated? How much time between each of those 3 shots?

 

[Elkmagnet]

I agree look for issues with the barrel contact first.

 

[sbhooper]

Was it also a freshly-cleaned barrel? It is not at all odd to have a high shot with a cold barrel, especially if it has been thoroughly cleaned. Shoot a couple rounds through a cleaned barrel and the rest will settle in just fine-if everything else is right.

If you hunt with a freshly-cleaned barrel, you may very well miss the first shot. After cleaning, always foul the barrel before final sight-in and then leave it alone for the rest of the season. Cleaning is not a friend, unless the groups start to open up due to fouling.

Welcome to the swamp.

 

[TheJason]

My guess is a bedding issue, provided you are not cleaning in between groups.

 

[csutton7]

By freshly cleaned did you run a couple of dry patches down the pipe before you shot that first shot? It's usually a good idea to do so and I'd say it's mandatory if the pipe had an oil patch ran down it as the last part of "Freshly Cleaned".

 

[Bowhunter60]

Not familiar with the TC but is the barrel free floated? How much time between each of those 3 shots?

The barrel is free floated. Very good barrel and very good rifle. I can easily manage sub MOA shots pretty consistently. I typically shoot 150g and larger in sub 1" groups. This is the first time I've had the cold barrel shot perform so differently.

 

[Bowhunter60]

Was it also a freshly-cleaned barrel? It is not at all odd to have a high shot with a cold barrel, especially if it has been thoroughly cleaned. Shoot a couple rounds through a cleaned barrel and the rest will settle in just fine-if everything else is right.

If you hunt with a freshly-cleaned barrel, you may very well miss the first shot. After cleaning, always foul the barrel before final sight-in and then leave it alone for the rest of the season. Cleaning is not a friend, unless the groups start to open up due to fouling.

Welcome to the swamp.

I agree Hoop