Accuracy problem after barrel threading

[txfireguy2003]

LONG story short, I had my favorite, most accurate rifle, cut and threaded for my incoming suppressor. Took it to the range yesterday, and something is very wrong.

First group of 4 had a fouling shot and 3 into just under an inch, but those were sighters anyway. Adjusted scope and fired a 5 round group, under 1/2" including my typical 5th round flier. The other 4 were in the 0.3 range. I was pleasantly surprised, considering I was using the same load from when it was 6"longer! I then shot another 5 round group, first 4 just over 0.25" with the fifth opening it to just under an inch. Then it went down hill fast! The very next group was very near 2", and it never got better than 1" after that.

I gave up, headed back to the man cave and stripped it down, thinking my scope base had come loose....nope, all four screws tight. Checked the action screws, they were tight.

I just can't figure out what's wrong with it. I wanted to blame the gunsmith's work, but those two excellent groups would seem to indicate that the crown at least is okay. Maybe barrel heat, non free floated stock, cheap Tupperware stock etc, but I never had this problem before. Any ideas? Thks rifle had never fired a group over 3/4", even when I was working up a reload trying different charges etc. Now all of a sudden, it sits a couple of good groups like it always did, then, trying to crap. What could it be?

[RingSteel]

Was the ambient temp a lot higher this time than last time you shot?

Barrels take a lot longer to cool in hot temps, and not being free-floated shows up more often. Just a thought.

[txfireguy2003]

Yeah, it was a bit warmer. And I did think about the barrel heat at one point, and let it cool. Not sure how long, but I took the bolt out, pointed the muzzle into the breeze, and walked down range 100 years, looked at the target closely, walked back, sat down and sent a couple texts. The barrel was cool enough that I could rest my hand on it indefinitely without experiencing any discomfort. The groups tightened up after cooling, but not anywhere near back to where they were. The vertical stringing would seem to indicate issues with free float/heat.....

[txfireguy2003]

First four rounds, all aimed at center diamond.

[txfireguy2003]

First 5 shot group after making scope adjustment.

[txfireguy2003]

Second 5 shot group. Notice both groups have a flier, I do that every time, it's me not the gun, I see a great group taking shape and get nervous and pull the fifth shot.

[txfireguy2003]

The very next group, what happened?



And the next.

[txfireguy2003]

Not sure why it's rotating all my pics. All text should be upright and strings should be vertical.

[txfireguy2003]

So I let her cool down and fired the 4 groups you see at the corners of the main diamond. The .915 group is with Hornady TAP, the rest are my hand loads with the same bullet. The 10 round group was pretty much rapid fire out of frustration, just to burn up my remaining bullets. Everything else was fired slow fire, with very meticulous aim, trigger control etc.

[ItsLeo]

Shoot the gun until it gets hot again. Then tighten up the action screws while the gun is still hot. Those tupperware stocks sometimes get loose when the action heats up. You can never tell this is happening when you only check tightness after the gun cools down.

[hweissert]

maybe hot barrel slingers?. Really the only thing that makes sense if you were getting good groups at first. I know when I get frustrated with one of my rifles, the rounds seem to crack out much faster than if I'm calm, taking time, and not thinking wth is going on lol. But,the above makes sense too. I don't have any tubber stocks so no knowledge on that.

[txfireguy2003]

Well, I'm going to be replacing the stock soon anyway, this was just very frustrating, and confusing since it literally went from bug holes to all over the place from one shot to the next. I swore my scope base had come loose, but it doesn't appear that it did. We'll see what happens next time, but who knows when that might be.

[Jethro]

Factory loads or reloads? Could be the loads were in the accuracy node for the longer barrel length and when you cut it the vibrations are different. My need to re-tune your loads for the shorter barrel length if you were on the edge of the node.

Or, you probably really don't want to hear this, could be that you cut the barrel at a bad spot. If it is a factory barrel, they are not as consistent end to end as top end barrels. Could be it got cut at a spot not as condusive to accuracy as it was before.

[txfireguy2003]

It was hand loads for the most part. I figured I might have to adjust my load for the accuracy node, but remember, it shot a 0.343 group, followed by a 0.277 group. Then, something changed and it immediately went to shooting 2" groups. I would swear it was a loose screw or something broke, but I found noting of the sort.

[yanta61]

maybe it was shooter fatigue? I would check all screws on bases and scope mounts and action screws again. I hate hearing this because i have a 308 i would like to cut and thread. I'm now thinking maybe I'll just thread it and not mess with the crown.