MOA at 400 but can't get on target at 650?

[lyle2231]

Going to try again with follow through this weekend, it is a light rifle, browning stainless stalker with a Leupold vx5hd coming in at just over 7lbs. 300wsm no break.

Thinking out loud here...Call the outfit that put the gun together inquire what their shoot and cool cycle recommendations are. .3 shots in rapid succession heats a "pencil" barrell enough to cause a wandering zero

 

[CVCOBRA1]

Ten pages and not figured out yet......better just sell the thing.

 

[lyle2231]

Or limit shots to 300 yds??

 

[Ronald W Schaefer]

Remaining bullet velocity and rifling twist rate could be a factor...It is possible as the bullet slows down the rifling is no longer stabilizing the bullet.

 

[Ronald W Schaefer]

What I meant to say is as your bullet slows down the rotation also slows, perhaps it has slowed below the turn rate required to continue to stabilize the bullet beyond 400...

 

[Bruce Treloar]

What I meant to say is as your bullet slows down the rotation also slows, perhaps it has slowed below the turn rate required to continue to stabilize the bullet beyond 400...

Thanks Ronald, that's what is happening. It's not uncommon for a top bench or target shooter to have different loads, bullets etc for various distances. There has been a lot of excellent information over the years from target, sniper and F class shooters, "The Science of the Rifled Tube" rings a bell. Read McMillans article on Reading Mirage.
Better still join a target shooting club and when you have a rifle and knowledge to one shot humanely kill an animal at the distance you are ready to go hunting.

 

[Swiftkill]

Ya know, that cartridge is a 1500 yard round. (and can be shot out to 2000 or 2500 yards) Using a 1:10 twist and a 180 -220 gr bullet at 2700-2950 fps is right in the wheelhouse. 650 yards should be a chip shot. My money is on overheating the barrel too quickly combined with shooter's technique and, the dial is probably not matched exactly and THAT shows up past 500 yards.
AND, what about the bedding and screw torque? What type of bedding is in that stock? Can you torque the action screws to 40 or 50 in.lbs? (Dont try that with a plastic stock, 25 in.lb max)

 

[LazzInc]

Oh my lord ,,, if the rifle and action combo shoots, you can bolt the darned assembly to a 2X4" board and it will still shoot, you don't even need a stock ,,, I would get rid of the Carbon wrapped barrel ,,,

 

[Swiftkill]

I agree, you could bolt it to a 2x4, if it was consistent! If his stock is not secured or imparting varying stress to the barreled action it could cause problems. THAT being said, since it shoots at 400 it should shoot at 650. Therefore, it is either heating up or mirage and shooter error are the culprit, including his elevation dials that don't quite match his real world drop. If you are not shooting off a front pedestal rest and your forearm pressure is different from shot to shot then that could certainly be the problem. What else could it possibly be? His bullets are not becoming unstable at that distance.

 

[Swiftkill]

BTW, Hi Jon L. Nice to meet you and thank you for all you have done for the firearms industry.

 

[Deezel]

Ok back to the range this evening. I didn't have time to stretch it out but I did validate that I was still on at 100 yards.

Also shot 3 different type of ammo, ballistic silver tip shot 2 moa, Barnes ttsx shot 2 moa however the accubond shot 0.5 moa, I'll attach a pic below of one of my 3 shot groups with the accubond.

Next trip will be going back out to long range and trying to figure out what the heck is going wrong.

Ignore the group up high, that was Barnes.

Did you ever get a chance to try the accubonds farther out yet? Curiosity is getting to me.