[MontyF]

After a barrel has some shooting time on it does the load preference change? I'm not talking about a barrel that is erroded in the throat or has been shot out.

 

[kdub]

Think that's the time to start developing loads to determine the particular preference. IMO, it takes 50 or so shots to smooth out the kinks and burrs of a new barrel (excluding the lapped ones) to begin serious evaluation of just what combinations of loads the rifle likes best.

 

[MontyF]

This barrel had been broken in pretty well before load development. This .223 has maybe 1800-2000 rounds thru it now. Of course over the time since developing the load and now the powder lot and primers have changed. Now my rifle and handloads which previously shot groups in the .300s now is in the 1"+. Since I use this rifle on prairie dogs and seldom shoot paper this happened without me being able to nail down the cause. Took it out target shooting this weekend to check the scope since I'd been missing more than usual at the 300-400 yard ranges.

 

[kdub]

Doubt if the throat/bore is shot out with just that many shots through it, but you never can tell. I'm going to assume you have gone through all the standard checks on possible bedding shifts, copper/carbon buildup, loose screws and lighting or weather conditions.

After that, you most certainly could question the new powder and primer lots deviating from your former loads.

The one thing I question most for myself is the advancing age deal and not being able to see or hold as close as previously.

 

[700sage]

Wood stock or synthetic? Wood could have swollen or warped slightly creating a pressure point. Happened to a 700 classic in 7mm mag that I have. I just upgraded to a synthetic stock and it was better than new.

 

[41 Mag]

I had a 25-06 that I gave to my daughter a couple years back. Once I worked up the load I shot it year after year with nothing else done to it. Then one year it hit a bit high. I figured that it could have gotten bumped since we had been hunting a new place and it had way more travel time now. I simply adjusted it back to about 3/4" high at 200 and went on with it.

It shot like it always had that season and into the next, and then I noted it hitting high again. Same procedure adjusted it down to hit where it had always been hitting.


A month or so later it was again high, and I figured the stock was needing attention so I went to work on it and removed quite a bit around the channel, to which it held it's zero for about a year and a half and again was high. At this point I replaced the stock with a laminate, bedded the action, and it went right back to hitting the zero almost to the exact dial setting it had before everything started going weird.


Today it has held there going on 9 years and there hasn't been a time when I checked it that I didn't hit where I aimed.

Check the barrel for fouling and the stock for creepage. IT only takes a tiny bit of pressure to walk one around on you and it will drive you nuts chasing it.

 

[Big Z]

Load preference stays basically constant in my experience.
Anyways..
If it were me, I'd go back to the basics....I'd plan on re-tuning my load after doing a total breakdown/cleaning, and remounting the bases and rings TIGHT with threadlocker. Might try moving seating depth out a touch for a start. If the basics don't work, consider rifle/stock mating as the issue. The barrel should have way more life in it, and I probably wouldn't blame it.

 

[seatleroadwr]

I have a 308W with a Lilja barrel through which I've shot about 2000 rounds. The free bore has increased about .025" and I've had to change the COAL to keep the accuracy. Accuracy has decreased a small amount and every now and then I get an unexplained flier. If you don't change your COAL to chase the throat, you will definitly change the pressure characteristics of your gun. Also, when you change the COAL you will find that you increase the chamber size, thereby decreasing the pressure. Increase the COAL and toss in a few .1 grains more powder and see what happens.

 

[MontyF]

All good tips, thanks a lot for responding. Most of the stuff should be straight forward and easy to check since I have recorded bullet jam length, torque on action screws and original load development.

This is a lamanated stock and the barrel channel is free, clear back to the front of the action. The barrel really came around after break in. After brushing and a wet patch it always cleans without a smudge in three patches. I've been careful never to get it hot. I do need to check the scope mounting. Earlier I tried a different scope which didn't pan out. I took the original off the mount with the rings still fastened to the scope tube and bought new rings for the new scope. Since reinstalling the original I haven't rechecked the mount or ring torque.

Yeah my eyes have never been great and haven't gotten any better, but I do enough shooting I can usually tell if it was a good shot or pulled. I honestly don't figure the loose groups as being my fault. To check that it wasn't me a buddy who is a pretty good shooter, tried the rifle with very similar results.

 

[pisgah]

There are so many possible factors in such a change that the "why" can be hard to pin down. Certainly, different lots of powder or primers can make a difference, and there's not much we can do about that other than develop a new load. But my first suspicion would be a fouled barrel. You can think you are getting a bore clean, and it can look squeaky-clean, but stilll not be clean.

I well remember a .30-06 custom Mauser I had that was a tackdriver with its favorite load for years. When the accuracy went off, I nearly went nuts trying to figure out the problem. Then, a friend got a Foul Out unit and in desperation I tried it out (even though I KNEW that bore was clean!). The amount of copper fouling that thing removed was amazing, and the accuracy came right back overnight.