What would make a 100yd group open up by a factor of 5x at 200yds?

[Shinbone]

Gun is an all-factory bedded Kimber Montana in .223 Rem shooting Berger FBT 55gn bullets over 26.4gn of AA2230 at 3400fps average velocity. These were shot off a bench with a front rest/bag and a rear bag. 2 foulers were shot from a clean barrel before the groups. 1 minute between shots, 20 minutes between the two groups. Close to zero wind.

I know MOA size can be expected to open up some as the range increase, but 5x from going from 100yds to 200yds is ridiculous.

The ES isn't great, but it isn't enough to blow up a group that much at 200yds . . . ?


At 100yds, group size is 1.15", ES = 104fps:





At 200yds, group size is 5.37", ES=120fps:




Had almost similar results with a Ruger Hawkeye in .223 Rem at the same shooting session.

At 100yds, group size is 1.05", ES=100fps:




At 200yds, group size is 3.66", ES=144fps:

 

[Mark M.]

Tell us about your optics

 

[hogpatrol]

What kind of load workup did you perform? Offhand, it looks like an unstable load.

 

[joshb]

Ditto. Can you work up your load at 200 yards?

 

[AJC]

I would be looking for a different or better bullet

 

[Dub]

Over an inch at 100 is not a great load. Keep working on it

 

[Terry]

You have your answer. ES

If it's big at 100, it will be crap all the way out.

 

[M-61]

If I read this correctly you have two different rifles that are not holding or under one inch at 100 yards. Not really familiar with factory rifles but in today's world what I read is less expensive rifles than yours will shoot under one inch.
I would work on your 100 yard group and get that under control. Going out further won't help you now.
And I would go thru all the basics on both rifles...meaning scope rail and rings tight....action screws secure....and the only common factor here is really YOU the shooter. It's nice to have a friend just watch how you are setting up and shooting.

Long time ago I started trap shooting....a disaster. Had friend watch me and he wanted to duct tape my head to the stock as I kept lifting it and didn't have any idea until he told me. I would not let him use the tape!!
Good shooting and stick with it.

 

[K22]

Not familiar with AA2230 but 3,400 f/s in a 223 Rem with 55 grain bullets seems to be pushing the max. An older data book I have for Accurate Powder show 24.7 as a max load.

Perhaps if you scale back the load a bit it might tighten the 100 yard group. Like someone else said, I'd strive to get that 100 yard group down well under 1" before I'd be concerned about 200yards.

Powders that have worked well for me in the 223 Rem with 55 grain bullets are H4895, H335, Varget, and Benchmark. But first I'd try a different bullet before changing powders. I've had a lot of success with the 55 Nosler in 9 and 12" twist rifles. While I've gotten the 55 to shoot well in my 8" twist rifles, I had to scale back the powder charge, i.e. velocity, to get them to shoot.

 

[AllenOne1]

ES at 100+ is probably were your issue starts. You will need to check everything but I would first look at how you are measuring or dumping powder. You have a small case capacity and you will need to measure your powder charge and keep them tight to get a lower ES.

 

[Metal God]

Two different rifles doing the same thing , it’s the nut behind the wheel :-( tighten that up and you should be good to go ;-)

 

[dgeesaman]

Are your scopes parallax set exactly right for 200y? What about mirage?

 

[WyleWD]

Are your scopes parallax set exactly right for 200y? What about mirage?

+1^^. Also are you using windflags, and a sporter weight barrel?? WD

 

[Dusty Stevens]

Its that wind, i know it is.

 

[Shinbone]

Thanks for all the great questions and comments. The only two things in common for all the groups was the shooter and the handloading. Looks like the best option will be to start over with load development with a new powder or bullet. I need to focus on lowering the ES while I am at it, too. I'll shoot some other proven guns at 200yds to improve/confirm marksmanship, too.

To answer some of the questions folks asked:

1) Each rifle has a Zeiss Conquest 3-9x40 scope. This scope doesn't have parallax adjustment. I did check for parallax error by moving my eye in relation to the ocular and see if the cross hairs appear to move in relation to the target. Parallax looked good for both scopes when I did this check at both 100yd and 200yd. I did have to refocus the reticle when moving from 100yd to 200yd on both scopes - scope settings were not touched while shooting each group. There was no mirage.
2) Yes, I am running a hot load. No ejector mark or hard bolt lift, though.
3) No windflags, but there was no wind, either.
4) I am happy to switch to another bullet, but I thought the Berger Flat Base Target bullets had a good reputation for accuracy. This is the first time I have used the Berger (or loaded for .223 Rem).
5) The rifle has the factory sporter-weight barrel.
6) Powder is dispensed by an Autotrickler/A&D Fx-120i scale to plus-or-minus 0.02gn accuracy.

This is an interesting thread which has some good load suggestions for me to try.
http://forum.accurateshooter.com/th...develop-a-load-update-w-range-report.3959557/

And this is an interesting article on how ES affects accuracy at short and long range. It suggest ES would have to be quite big to have much of an impact on group size at 200yds
https://www.gunsandammo.com/editori...-extreme-spread-and-standard-deviation/247510

 

[Coyotefurharvester]

My eyes are old, I like 16-20x and a 0.25 moa dot for load development. I have seen scopes shift poi when changing the ocular focus, that and power setting. Need repair or replacement. Seen people rest the barrel on bags and wonder why groups open up greatly as distance increases.

 

[JFrank]

Those scopes should be good

 

[dgeesaman]

1) Each rifle has a Zeiss Conquest 3-9x40 scope. This scope doesn't have parallax adjustment. I did check for parallax error by moving my eye in relation to the ocular and see if the cross hairs appear to move in relation to the target. Parallax looked good for both scopes when I did this check at both 100yd and 200yd. I did have to refocus the reticle when moving from 100yd to 200yd on both scopes - scope settings were not touched while shooting each group. There was no mirage.

3) No windflags, but there was no wind, either.

And this is an interesting article on how ES affects accuracy at short and long range.
https://www.gunsandammo.com/editori...-extreme-spread-and-standard-deviation/247510

If you are playing with the ocular adjustment it is not really a parallax adjustment. But you are assessing parallax correctly by moving your eye around.

If you have no windflags, you only confirmed there isn't wind at the bench. The other 199 yards are unknown.

Mirage can also "bubble" in some windless conditions. It's frustrating for sure. When the air on the ground is slowly cooling or warming, it blobs of air will suddenly invert. The scope's crosshair will shift due to the change in air density, but unless you catch it as the air inverts, you won't know. So 'perfect' conditions aren't just lack of wind and good visibility, for me I'm also looking for constant temperature and no warming/cooling taking place.

Forget ES. That article shows it might contribute to a couple of tenths. You're looking right now for inches.

I realize this isn't rimfire, but in testing my Anschutz 1907 recently at Lapua, it would produce solid 50m groups but those same shots would have a few fly wide by the time they got to 100m. A 5/8" 50m group would be 3" at 100m. Barrel cleaning and ammo selection mostly eliminated this.

David

 

[JFrank]

The ocular adjustment is to ensure your eye see’s a clear sharp image of the reticle.
I don’t try to focus the target on this adjustment.

To get an ES of over 100 it seems half the powder would be missing on half those rounds.
I didn’t catch what twist rate barrel are you using with the 223 I’m also not a 223 guy but some people have a hell of a time getting the right combination.
I would start over by reviewing the components selection.
You’ll get it figured out that’s for sure.
J

 

[coldboreshot]

Gun is an all-factory bedded Kimber Montana in .223 Rem shooting Berger FBT 55gn bullets over 26.4gn of AA2230 at 3400fps average velocity. These were shot off a bench with a front rest/bag and a rear bag. 2 foulers were shot from a clean barrel before the groups. 1 minute between shots, 20 minutes between the two groups. Close to zero wind.

I know MOA size can be expected to open up some as the range increase, but 5x from going from 100yds to 200yds is ridiculous.

The ES isn't great, but it isn't enough to blow up a group that much at 200yds . . . ?


At 100yds, group size is 1.15", ES = 104fps:





At 200yds, group size is 5.37", ES=120fps:




Had almost similar results with a Ruger Hawkeye in .223 Rem at the same shooting session.

At 100yds, group size is 1.05", ES=100fps:




At 200yds, group size is 3.66", ES=144fps:

Curious, the first picture, was that shot from a cleaned barrel? looks like shots 1 and 2 are fouling and tracking in toward your point of aim on the target and 3,4 and 5 have settled in. Also, if 2 different rifles are producing same results, I would consider your set up on the bench at 200 yards. Might be something as simple as your positioning on the bench and on the gun. It seems to be repetitive. This is just one possibility but might be a significant one.