Groups that get larger...

[gspn]

I've got a rifle that's giving me fits. It's a bolt action .243 (Marlin XS7 youth) with a Bushnell Banner scope.

Today it shot about a 4-inch group at 100 yards with the first 5 shots. I'm not cool with that.

The next two group (5 shots each) saw the groups grow to over six inches. It wasn't vertical stringing...it was just kind of all over the place.

The barrel is clean, the ammo is good, all scope attachments are solid tight.

At first I was thinking that maybe the stock was contacting the barrel as things heated up but then I started to think maybe the scope is just a turd.

Any ideas what could cause this?

I just slapped a Leupold on it that i had laying around...I'll try that out this weekend and see if it fixes it.

 

[floorit76]

Torque the action screws. Better yet, bed it, then torque them. Better scope couldn't hurt. How long between strings? Getting hot?

 

[gspn]

I'd give it enough time between groups that the barrel could cool almost completely. I'd set the .243 down and we'd shoot some with the other rifles...probably 20 to 30 min between groups.

 

[flatlander937]

This started happening to me today on my 10/22... the action screw on the bottom was working loose. Tightened it up and went back to respectable 3" groups at 100yds(for a bone stock 10/22 I'm happy with that).

 

[Jackal]

Check your bases, are they tight? Bushnell Banner scope are sort of a turd, I have had a couple fail and one was on a .22....:banghead:

 

[redneck2]

Could be just as simple as the ammo. I have a CZ in .204 Ruger. First "groups" looked more like shotgun patterns. Worked up hand loads with 39 Blitz Kings. Shoots .4's now

Same thing with my custom AR in .358 WSSM. I started quite low as it's a wildcat, so there are no real clear loads developed. First groups were in the 6-8" range. Now it shoots right at 1/2". Had to crank it up about 3 grains to get it to shoot.

I suspect it was a combination of getting some rounds down the barrel along with the right loads.

You did the first thing I'd do...change the scope. Quite frustrating to keep trying loads and finally figure out the scope is bad.

 

[Temp430]

It could be copper fouling. To make sure it's not, clean the barrel thoroughly with an ammonia based copper remover. If the barrel is clean and it shoots other ammo fine then it's the ammo.

 

[denton]

There may be no actual difference in the performance of the firearm.

The worst sewer pipe barrel you can find will eventually shoot a 1/2" group if you keep at it long enough. There is normal, random variation in group size. Some groups will be better than others, just by random chance.

When looking at situations like yours, an important question to ask is, am I seeing real change or am I seeing normal, random variation? You might just be seeing normal random variation.

Rule of thumb: The average of three five-shot groups gives you your long-term average group size plus or minus 25%. If the average of three five-shot groups changes by more than 25%, then there is a very good chance that you're seeing real change.

 

[Grizzdude]

The ole Bushnell Banner, I had one of these laying around, put it on my .308 and got 4"-5" groups at 100 yards. I switched to a $200 leupold and shot a 3" group at 600 yards the next day. Now I use the bushnell banner on the .22lr, seems to work ok on that. That scope is pretty old and if it's like mine it won't group with anything that recoils. good luck!

 

[Clark]

I go to the range with my beater rifles and help other shooters.

Half of my problems and other guy's problems is loose scope base screws. That is not your problem.

You may have:
1) Copper fouled bore
2) Wind picking up
3) Loosing concentration from being tired or getting kicked with recoil.
4) Loosing light late in the day and pupils dilate making scope blurry at a high power that worked an hour ago.
5) Barrel getting hot from shots too close together.