Sierra Heavy TMK 6MM Testing

[HairyScandinavian]

Did a temp test with imr4350. 5 rounds in 0 degree freezer and 5 very warm wrapped in a hand warmer. I didn't have a thermometer to check temp. At the ranges I would shoot at an animal, say 500 yards, is a difference of .2 mil.
I wonder how much better performance I'd see with h4350 or n555

Did you chrono it? Curious as well about the H4350, goofing with GRT it shows more than expected velocity changes when I change the temperature, but I don't know where their model data comes from so not gonna blindly trust it.

 

[coya]

I

Did you chrono it? Curious as well about the H4350, goofing with GRT it shows more than expected velocity changes when I change the temperature, but I don't know where their model data comes from so not gonna blindly trust it.

I sure did.
Cold 2941
Hot 3029

 

[ID_Matt]

Shot the 107’s again today. I think these are going to be my go to for hunting season. Settled on 2970 FPS in the 18” 6 creed. Trending slightly low. Need to shoot it a bit further to true BC probably.

500 yards



600 yards

 

[KingOfTagSoup]

I've got the 107s in my 6 ARC bolt gun averaging 2777. Suppressed it's fantastic to shoot.

 

[Chris in TN]

Did you chrono it? Curious as well about the H4350, goofing with GRT it shows more than expected velocity changes when I change the temperature, but I don't know where their model data comes from so not gonna blindly trust it.

GRT uses a very generic one-size-fits-none approach to temperature. There's a mechanism within GRT that allows you to input your own temp data and calculate a predicted change per degree, but I've never tried to do anything with it. Most of my actual velocity testing is done from my barn window and the barn stays 50 to 75 degrees almost year 'round so I don't even worry about measuring that. If I'll be in extreme cold conditions I'll use the manufacturer's stated temp coefficients, if they're known.

 

[Jake Leibke]

I've got the 107s in my 6 ARC bolt gun averaging 2777. Suppressed it's fantastic to shoot.

What’s the details on the gun and load?

I’ve been trying to get them to shoot good. Best I can do so far is about 1.5 moa.


Sent from my iPhone using Tapatalk

 

[HairyScandinavian]

GRT uses a very generic one-size-fits-none approach to temperature. There's a mechanism within GRT that allows you to input your own temp data and calculate a predicted change per degree, but I've never tried to do anything with it. Most of my actual velocity testing is done from my barn window and the barn stays 50 to 75 degrees almost year 'round so I don't even worry about measuring that. If I'll be in extreme cold conditions I'll use the manufacturer's stated temp coefficients, if they're known.

Thank you for clarifying that, good info. I may toy with it some day but if I can shoot instead that's best.

 

[Plague]

Got out and shot some of my 107 6arc load with a buddies garmin today. 2975 average muzzle velocity. 31.5 gr of lever with a cci srm and Hornady virgin brass. 21” barrel. Slightly heavy bolt lift. 10 round groups are holding right around .8-.9 moa.