Quick question, root cause of 2 + 1 groups?

[Darryle]

I have a rifle that consistently does this, regardless of who's shooting it.

I get 2 essentially in the same hole then one right on the edge.

280 Ackley Sammi 26" proof barrel, this was with the EC Tuner brake, but it will do it with a standard brake or thread protector.

140gr Nosler Accubond factory

50ish rds thru the barrel

 

[sedancowboy]

Barrel might be warming up? Where does it print a group of 5 shots?
Barrel could be touching stock. Depending on type of stock try tightening the action screws.

 

[bill123]

Agree with the 5 shot group question. Is it always the third shot? What type of rest? It would be more helpful to see an entire shooting session with groups like that. It could be that the gun is shooting fine but you are slightly pulling one shot. The shot you are talking about looks to be about 1/8" away from making that group a perfect clover leaf.

 

[dfanonymous]

Barrel expansion from warming up.

A good way to test is to let 10 minutes sit between each shot.

That said, I wouldn't do anything less then a 10 shot average. I never got the point of a 3 shot group. Thinner profile barrels you'll notice more of this shift.

This is all assuming you're at 100y. Further than that, and it introduces more variables.

 

[Darryle]

Caldwell The Rock Deluxe Front Rest, Caldwell rear bag, I have not tried 5rd groups, but I will next trip to the range. Barrel is free floated to within 3/4" of the recoil lug. I loosened and torqued the action to 35in lbs front and rear, front screw first and then rear working equally between the two, didn't seem to make a difference.

Always the 3rd round, with a "generous" amount of time between shots. (Subjective)

Next trip, I will take this rifle and use my barrel cooler and give it 5 minutes between shots, possibly 10 minutes. Depends on how busy the range is or crowded.

I see this anomaly occasionally mentioned in threads and have always wondered what caused it. This is the first rifle I have had that consistently exhibits this problem.

Any other suggestions?

Thanks

 

[dfanonymous]

Caldwell The Rock Deluxe Front Rest, Caldwell rear bag, I have not tried 5rd groups, but I will next trip to the range. Barrel is free floated to within 3/4" of the recoil lug. I loosened and torqued the action to 35in lbs front and rear, front screw first and then rear working equally between the two, didn't seem to make a difference.

Always the 3rd round, with a "generous" amount of time between shots. (Subjective)

Next trip, I will take this rifle and use my barrel cooler and give it 5 minutes between shots, possibly 10 minutes. Depends on how busy the range is or crowded.

I see this anomaly occasionally mentioned in threads and have always wondered what caused it. This is the first rifle I have had that consistently exhibits this problem.

Any other suggestions?

Thanks

What's the barrel profile?

 

[Darryle]

Proof Sendero Carbon

 

[dfanonymous]

Ok. Yeah, proof carbons dissipate heat quicker, but they generally get hotter faster.

Like I said, if you wait as long as possible between shots, (more than 5 minutes) and you still get the same problem, then there's a harmonic or load issue.

 

[Mikecr]

I get 2 essentially in the same hole then one right on the edge.

This can be the biggest mystery and challenge with a gun. Could be any combo of many things.
It is for this reason that I've had horrible grouping guns -that provide fantastic hunting accuracy, and great grouping guns -that are too inaccurate for hunting.

 

[Roughrice]

Well Darryle,
Looks to me that if this a hunting rifle... you are locked in pretty dang good.
You can do 5 shot or 10 shot groups if you want to, but... When my hunting rifles put a clover like that, I'm done.
Maybe do 5-10 shot groups if you're going to a LR match,, but...for hunting...you know you are good!
Very few have to put more than 2 in an animal and those first 2 are in the same hole to me!

 

[Darryle]

It is a hunting rig, was curious about the why's and fors of this scenario.

 

[Roughrice]

I'm with you on that one Darryle!

That's exactly why I use SS lightweights or Carbons for hunting and the heavy SS for long range competition.
I never worry about longer shot strings for hunting rifles because they WILL drift with heat.
3 shot groups is good enough for me in a hunting rifle.

I'm not a professional but I'm sure someone can back this up.

 

[Calvin45]

Cold bore + 2

 

[Darryle]

Cold bore + 2

Nope

Clean cold bore was well away from the group, now this rifle gets cleaned and then I fire a couple out of the back of the shop to foul it. The clean cold bore issue disappeared.

Full target