What causes a rifle to regularly shoot two groups in one string?

[Chuck]

I've got a Ruger #1B .270 Winchester that seems to have lost its mind. I've had it for six or seven years and it has consistently been my 3/4 MOA or better beanfield rifle. For the last month or two I can't get a good group out of it.

So far I've tried barrel cleaning, different scopes, different loads, checked forearm tension, different shooting positions, shooting on multiple days, etc. I feel like I have considered a lot of variables yet when I shoot it will put four shots into say 1.75" at 100 yards with pairs touching or very close to it.

There has to be a specific problem here but I don't know what it is. For a while I really thought it was just me but shooting has been good with my Ruger Ultralight .30-06, my .30-30, my 375 H&H and my M1A, a pretty broad range of rifles, often shot at the same range session as the .270.

Anyone know what my problem might be other than a rifle that is possessed by evil spirits?

 

[John Y Cannuck]

To me this sounds like a bedding issue. Barrel heating moves group.

 

[smellie]

Bedding or stock, definitely.

If you shot Lee-Enfields, you would be familiar with The Damned Crack. Have one here that consistently shot a pair of 1-inch groups, one a foot above the other. Took it apart, fixed The Damned Crack, set the bedding up the way it was done at Lithgow in 1918 and it now shoots consistent half-inch 'hunter/sniper' groups at 100. Not bad for 94 years old, I would think.

The Ruger has a 3-screw bedding system. That angled middle screw has to be tightened in concert with the others. Try slacking off all 3 screws and doing them up together, see if that helps.

Be sure the barrel floats ahead of the chamber and that the action is tight in the wood.

It is possible also that a pressure point should be installed at the fore-end tip.

This has helped several Rugers on which I have worked.

Good luck.
.

 

[Lefty Dick]

It's not un common for #1's and their 1/4 rib scope mounts to do weird things.

The barrel heats up and th 1/4 rib gets a bit distorted because of the heating up of the barrel, and then your groups move around.

Try 2 shots and let it cool, then 2 more shots, and cool it out, then try a 3rd 2 shot group, I'll wager your nice tight group comes back.

Another thing to watch is where you sit the forend in the front bag...keep the front bag as close to the receiver as possible.

Don't shot a 2 piece stock from a bipod, if you want tight groupings.


Good luck

 

[vviking]

To me this sounds like a bedding issue. Barrel heating moves group.

Most likely. ^

Have you done an aggresive carbon and copper bore clean?. A 'carbon ring' in that first inch of bore can really open groups, and also can move pressures up and out of your accuracy node. Had one 6.5x55 that went way over-pressure and sprayed it's bullets with mild start loads, that is until the 2 thousanth's thick carbon/cupro nickle fouling ring was removed ... then she shot comfortably into 3/4 moa, with 5 grains more powder in the case.

Have you put a lot of rounds down the pipe?.
The .270W is an intense load, maybe the throat is going away?.
If so, the groups will seem to gradually get bigger, with mostly random dispersion.

If 'double group' is what your seeing ... likely that notorious #1 fore-end bedding we hear of, or, a bad scope. You've changed scopes, so bedding, fouling, or something loose.

Most unlikely to be the shooter, .... if you weren't a good shot, you would not have noticed a problem to be concerned with.

 

[mossyhorns]

I feel your pain. I have a #1B in .270 WTBY Mag. Was never a tack driver but shot select loads in the 1 1/4 inch range which was plenty good enough for me. Last year it starting stringing rounds all over the place. Mostly vertical but ocassionally off to one side or the other. I've cleaned it, tried new hand-loads, messed with the tension on the forestock screw and played with the float on the stock a bit (nothing permanent just wedges on the pressure point and hanger.) and so far nothing. All of my groups are shot with 5 min between rounds so the barrels not excessively over heated. I don't suspect the throat but honestly I haven't look yet either.

It's Still doing it and driving me crazy. Right now I'm at a cool down stage. It's in the safe for a few weeks until I'm ready to tackle it again.

I know a few guys that have had luck with bedding the forestock and I'm thinking of trying that next.