Post clean accuracy loss

[CCT125US]

Prior to cleaning:
Win 130gr FMJ
7yd / 10yd irons and LG-405


25yd 2 with irons, 2 with LG-405


Bore snaked, wiped down.

Now accuracy is gone. Shots are trending to the 5 o'clock position by 6 inches. Sometimes with vertical stringing. Known good ammo, be it handloads or factory.

Any ideas on what the heck happened? Definitely needs to see a smith. Possible crown or forcing cone issue. Not sure how a boresnake could have caused this.

[CCT125US]

Would this do it?




Possibly dinged in range bag? Pulling a snake through wouldn't roll metal.

[JAH 3rd]

Now that's a head scratcher. Muzzle and and forcing cone areas certainly can affect accuracy. Is the cylinder locking into the cylinder stop with each pull of the trigger? I just don't know how a boresnake would affect accuracy by just pulling it through the barrel. Has the trigger pull deteriorated causing pulled shots? Others will chime in here. Like you, I am interested in any ideas.

[willie]

I think that the larger groups are a coincidence. However, cast bullet shooters often insist of fouling the bore by firing a few rounds to add lube to the bore. A squeaky clean bore in this case would create more friction between jacketed bullet and barrel for the first few shots. Lower velocity is a result. Another possibility is variation in ammunition--even if all are from the same box. Don't laugh, but once I traced extreme variation to loose grips.

[4RNR]

LG is off?

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[GJM]

I have heard multiple custom gunsmiths say that overall, more barrels have been hurt by cleaning than helped by it.

[TCinVA]

Would this do it?




Possibly dinged in range bag? Pulling a snake through wouldn't roll metal.

Damage to the crown will certainly not help matters any.

Fouling in a barrel is a thing, but a radical shift in point of impact would seem to indicate something else going on.

[willie]

When shooting outside, position of the sun can effect point of impact when using fixed sights.

[john c]

Before you do anything, I recommend you have another known-good shooter shoot it. Just to make sure they’re getting the same results you are.

The next thing I’d do is clear it thoroughly with a conventional cleaning rod with a bore guide/crown protector.

The suggestion to check the grip screws is also excellent. Just go through the whole gun one step at a time, from lockup to timing.

If that doesn’t work, try shipping to a gunsmith.

Good luck, and that’s a serious bummer.


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[jh9]

Since it's an aluminum gun I'll just ask: do you see something like this?



Random picture from the internet, not mine. Look closely, it could be a much smaller crack.