Weird groups

[Flynt]

I've recently acquired an old Ruger 44 carbine, the finger groove model. The gun's a beauty and seems to have been fired and used very little. I want to use her for a pig gun, with ranges of about 50 yds. Since my eyes don't work too well with iron sights anymore, I mounted a Leupold 2-7 Rifleman scope on her.

I get good groups at 50 yds, usually small cloverleafs. However, there's no consistency. I'll shoot a tight group, stop, reload, and shoot a second group, but the groups will be an inch or two apart. Could this be a parallax issue? In other words, since I'm putting the gun down to reload, I'm sure that I'm looking through the scope at a slightly different angle.

 

[taliv]

maybe your sights are moving

if you want to see if it's possible that parallax could be the issue, put the gun in a rest and look through the scope at a target. watch to see how far the crosshairs move as you move your head as far as you can from side to side and up and down. my guess is it's not a parallax issue

 

[Flynt]

Sights are tighter than a drum. I'll try what you suggest. Thanks.

 

[dorothykinder]

You mean to say are you loosing your sights when its in firing position.. you could probably make it go for rest for sometime and then Reload it.

 

[Fremmer]

Are you holding and shooting the same way (consistently) for each group?
Is the barrel heating up?
Do you have an issue with that action moving in the stock?

 

[Al Thompson]

Try another scope.

 

[Flynt]

Thanks for all the responses.

I'm shooting 3-5 round groupsfrom a bench using sandbags. I have to reposition the rifle a little after each shot, due to recoil. Then after each group I have to change my own position and that of the rifle in order to reload. I try to be as consistent as possible when it comes to holding the rifle, but I know I'm not perfect. As far as I can tell the scope is secure to the rifle and the barreled action and stock are secure.

 

[Tim the student]

Flynt, just to clarify, you mean that the two groups are both good groups, but with a different point of impact, correct?

Are the two sets of groups consistently in the same place (relative to the point of aim), or are they all over the place (while still being tight groups)?

How long are you waiting between groups? Just long enough to reload, or longer?

 

[BADUNAME37]

About 30 years ago, I had a Remington 700 in .270

I had the exact same problem and when I took it to get it glass-bedded, the gunsmith showed me how there was a high spot in the wood - just under the barrel at the end of the stock.

He showed me how, you could push the barrel one way and it would kind of stay on that side of the spot, then push it the other way and the barrel would stay on the opposite side of the raised spot!

After having it glass-bedded and free-floating barrel, that problem went away!

 

[Flynt]

Tim, Yes, they are good groups, but the point of impact shifts a an inch or two between groups. I am not waiting for the barrel to cool. I'd assumed that it wasn't that important under the circumstances. I'm shooting at 50 yds. with a .44 that's not supposed to be capable of great accuracy.

 

[Jim Watson]

I suspect it is caused by having to break down your position to reload and not setting back up EXACTLY the same to shoot again.

 

[NMGonzo]

Thanks for all the responses.

I'm shooting 3-5 round groupsfrom a bench using sandbags. I have to reposition the rifle a little after each shot, due to recoil. Then after each group I have to change my own position and that of the rifle in order to reload. I try to be as consistent as possible when it comes to holding the rifle, but I know I'm not perfect. As far as I can tell the scope is secure to the rifle and the barreled action and stock are secure.

I tried the following and it worked; I was twisting my torso a little bit and my shots kept "walking" that direction.

Now they just group or worm down.

Same; sitting on a bench with sand bags.

 

[Dr T]

Shoot a 10 shot string and watch what happens.

 

[wombat13]

maybe your sights are moving

if you want to see if it's possible that parallax could be the issue, put the gun in a rest and look through the scope at a target. watch to see how far the crosshairs move as you move your head as far as you can from side to side and up and down. my guess is it's not a parallax issue

I'm no expert, but I've always heard that parallax is more of a problem at magnifications of 10x and higher and at ranges in 200 yds or greater.

 

[Tirod]

I'm shooting 3-5 round groupsfrom a bench using sandbags.

You are experiencing exactly why small groups are an imprecise and inaccurate way to measure.

As the Dr said, shoot 10 shot groups, at least three. THEN you have a good measure of what the rifle really does. The military uses ten shot groups to determine accuracy when the contract is on the line, and ten shot groups on the firing line. Anything less will result in only getting a smaller sample that has a much higher rate of error.

The reason the center of the group seems to be shifting is that BOTH groups are indicative of what the gun is actually doing. Without going into a lot of statistical math, etc., if you shoot ten shot groups, you get to within 1% of what the gun really shoots. Three shot groups are three times more inaccurate to base conclusions on, as you are actually seeing. Darn thing is shifting all over.

Not really. Combine the three shot groups into one composite and compare it to a ten shot, they will basically mirror the same conclusion - they will measure the same within fractions of an inch.

Go one step futher and use the milspec standard of determining the "Mean Radius," which is pretty simple math. You'll discover the average distance a shot will land from the center of the group, which is a much more informative answer to what the shooter and gun do.

Three shot groups are fun to brag about, but 10 shot are used to decide multimillion dollar contracts. The numbers were worked out in the 1950's, and that's what's used to determine accuracy by the pro's.

 

[cowart]

shoot 10 shot groups, at least three

The OP can't do that - his problem is that his POI shifts when he reloads. The early Ruger 44 only holds IIRC 5 rounds, so he is forced to reload after 5 rounds.

 

[Tirod]

Reloading isn't the problem, it's just shooting a few shots and then measuring that. Statistically, the small sample has a higher error rate.

As for reloading, there are a lot of things that happen in the field or in combat to challenge accuracy. Barrel heating, semi auto loading, bullet set back from weak crimps, non concentric loads, position shifts or cheek weld changes, ad infinitum. We all suffer from that, what you get when shooting a ten shot group is a little of that. It's certainly more indicative of the total package than a special benchrest bolt action in a sled and fired at a rate so slow it cannot heat up. Nonetheless, even the benchrest rifle will show a more indicative group with ten shots than three - the sample size is larger, and all the bullets are counted into the result, not the two worst and furthest from each other.

While accuracy buffs will tend to avoid any practices that create inaccuracy, the military uses the ten shot group fired three times to get a real world figure that reflects what the barrel and ammo do. It's one of the reasons why military spec M16's fire 2MOA - not 1/2 MOA as so many attempt to post with their cherry picked targets.

2MOA is still less than minute of soldier inside the M16's effective range, which makes it good enough for government work. No sense spending more tax money than necessary.

 

[Fremmer]

Yeah, but having that shifting POI would drive me crazy.

Something is moving on that gun. The gun itself when shot (try a rest), the barrel/action, something. Start with borrowing/buying a rest, and let the barrel cool between groups.