Well, if it helps at all, I would not be happy with the results, either and would for sure look for a fix.

The fact that you COULD get one {albeit only one} group under 2-inches with a cold barrel {what I call "One Shot Groups"} indicates to me the problem lies with bedding or possibly barrel seating in the action, the latter being a guess.

Can you slug the bore and note the LAND diameter?

I want to be clear in stating I am not discounting the BARREL BORING and RIFLING as being a problem, only that the groove depth by itself is not a pure evil.

I still am wondering about two dimensions on these .303's; First, the bore/land diameter and second the width of lands. Narrow lands and oversize bores and groove depths together are not going to be a good recipe for accuracy.

Having said that, vertical stringing does not sound like a boring problem, but rather back to bedding/fitting. Unstable or erratically engraved bullets normally land erratically/randomly.

There could be a mix, however, of issues.

Having said all of that, 4-inch 5-shot groups at 100 yards was about the acceptance criteria for new Lee-Enfield rifles as stated in the ordnance material above. You might be saddled with a "Within Specification" reply from Ruger and be stuck with handloading and bedding trickery to get that gun to behave.

Best, and keep us posted.

Rod

{{Edit; I'll post some accuracy criteria for some other older rifles on a separate thread. The whole topic of what consitutes acceptable accuracy is a very interesting one.}}