The old “two-close-together, one-out” group syndrome.. Help!

[bobnob]

Ok so a mate has this Howa 1500 Varmint in 243. It has the alloy pillar Hogue stock and is floated well and truly free. He has bedded the lug but that’s it.

The first three groups were at 150y over bipod. No called fliers. The bottom right group was shot at 125y again over a bipod.

The mounts all appear sound and we’ve double checked fasteners. Scope has been tried on another rifle and is sound. We even tried another scope but we still get a lot of this two in, one out syndrome.

In most cases, in fact all four of the above, the two close ones are the first two of the group.

The load on this occasion was 87g Vmax in a proven factory loading - OSA Buffalo River made down here. Good Ammo. Results with handloads are generally similar.

The frustrating this is that occasionally, it will throw all three right with each other producing sub-half MOA accuracy. Go figure!

Anyone willing to offer an opinion on what might be going on here?

 

[JD338]

Try seating your bullets deeper in .005" increments, you should be able to walk that flyer right into your group.

JD338

 

[cvm]

In my mind this flyer problem is probably related to bedding.
As the first groups is said to be consistent something is causing a shift in the systems contact to the stock and its pillars/lugg after a few shots.
I recommend a trip to a gunsmith for a full bedding and stabilising of the stock.

 

[Silent Sam]

It may or may not be "flyers". It may just be indicative of the true group size. Three shots is ok to check zero but is not definitive to establish grouping ability. How does it shoot off of bags vs bipod?. If it ends up consistently shooting into two small groups I would suspect bipod or bedding or a reticle moving.

 

[salmonchaser]

So over the three years I've been on this sight I've seen this come up often. One of my first inquiries.
You verified your scope on another rifle, so that's good. Seems the simple, inexpensive step would be to shorten up as JD indicated. I saw results pretty quickly with my problem rifle.
I shortened .015.



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[bdbrown66]

Ok, honest question here. I typically don't play around with my seating depth much. Usually, I stick with whatever is specified by the load recipe that I'm using. But I know that many folks talk about getting peak accuracy by seating the bullets as long as they can, and reducing the jump to the lands. So, why would you seat the bullets deeper in this case? I'm not sure I understand the thought process. Not challenging the assertion, just trying to understand.

 

[Songdog]

Because most folks start all load development at a Max COAL, then there’s only one direction to go.... deeper.

Max COAL will be determined by either the lands, or the magazine. If you can get a bullet to the lands, and still fit it in the magazine.... then start there, or slightly off the lands. If the COAL to the lands is too long for the complete cartridge to fit/feed from the magazine, then you start at magazine length.

Looking at those groups, I don’t think seating depth is the issue... I think it’s either not a good load for that rifle.... or there’s something mechanical causing problems. Those stocks are notoriously flimsy in the forend, and theres not a lot of solid stuff to bed to.

I’d pull it apart, recheck tightnesses and tolerances, and reassess.

 

[Elkman]

As already suggested, seat the bullet a little farther in. . Sometimes a grain or two powder will change the group size. I have also seen this occur when the shooter, comes off the rifle after each shot or after a couple. This is always a very hard one to diagnose.

 

[bdbrown66]

Ok, that makes sense. In this case, I would suspect the bipod is torqueing a little bit. Try the same shots off a bench with bags and see if you get the same results.

 

[TackDriver284]

Similar 3 shot group patterns,,,could be a bedding issue. Might want to pull the stock off and check what is underneath.

 

[hunter24605]

I had this going on last summer..Turned out that parallax was off and if I moved my head, even a tiny bit, the next shot would be out..Easy to check with the "nod your head" test..I sent the scope off to get the parallax adjusted and the problem went away.

 

[preacher]

I don't trust those Hogue stocks off of a bipod myself. In fact, using a bipod "correctly" is not commonly known. Research it, google sniper or Long Range shooting techniques, etc. Just a tip...I use a Buddy Bag and leather rabbit ear rear bag instead of the typical semi-hard leather bag on an adjustable pedestal. It comes close to repeating what resting the rifle on a back pack,etc does in the field, only you are on a bench. I also use it over the truck bed, etc. when out in the desert. Keep trying everything you know....eventually you will reach a "this is as good as this rifle is going to get", then go have fun!

 

[fremont]

I've been there, brother.

Are all shots fired at the same time? I've been involved with several rifles--especially overbore cartridges, e.g. 264WM--where they would stop throwing flyers if you let the rifle cool down after the 2nd shot. Try shooting groups of two then wait and see what happens. That said, the advice around bedding and torqueing are spot on, because the gun theoretically shouldn't throw shots when hot if inlet/bedded correctly.

 

[bobnob]

Ok thanks for the thoughts and suggestions. You’ve given us some fodder. I’m also tending to think this is mechanical.

We actually pulled the mounts and replaced them last evening. I have no reason to look askance upon the mounts which were on it, but they’re a common denominator.

He’s going to try it again at his place hopefully today. Will report back!

 

[bobnob]

Just got a message from my friend. The new mounts tightened the groups right up. No fliers. I guess the fact that the fliers were out to the side rather than random should have been a hint.

I have learned a lot reading your responses. Some stuff was fundamental but sometimes I forget the obvious stuff!

Slow learner :roll:

 

[cloverleaf]

Great that you found the trouble. A guy can go broke and insane chasing the variables... :roll: . Curious what type of bases you started with? CL

 

[Vince]

Reading this and happy to see you solved the issue.

Far too often we forget to check the basic stuff.

Vince


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[bobnob]

Great that you found the trouble. A guy can go broke and insane chasing the variables... :roll: . Curious what type of bases you started with? CL

They were a fairly generic looking set of alloy Weaver style rings. Replaced them with a set of Leupold PRWs.

Good to get to the bottom of the mystery!

 

[JD338]

Glad you got the problem fixed.

JD338

 

[pharmseller]

Don't shoot three times.