What made my accuracy become horrible?

[JBT47]

How often do you clean your barrel? What is your cleaning method? You could have carbon build up in your throat and just beyond.

 

[Nature Boy]

How often do you clean your barrel? What is your cleaning method? You could have carbon build up in your throat and just beyond.

I'm aligned with JBT and others who have suggested this. I had a .308 that went to hell accuracy wise. Thinking that I had shot the barrel out I took it to the gunsmith for a potential re barrel. He looked in it with his bore scope then showed me that what I thought was a clean bore actually wasn't. Gave me a bottle of Boretech and told me to clean it per the instructions and shoot some test loads. I did what he suggested and accuracy returned to normal.

I promptly bought a bore scope and now inspect all my rifles as part of the cleaning routine.

 

[KylerB]

How often do you clean your barrel? What is your cleaning method? You could have carbon build up in your throat and just beyond.

It is a rifle that I hunt with so it typically I would clean it before and after season( not too many shots. Maybe 20 or so) I de-coppered probably 75 rounds ago. The next time I cleaned I was debating doing it again. I've always heard to not de-copper the barrel very often after initial break-in in order to leave the barrel "seasoned."

 

[KylerB]

Since you've already reloaded the same cases with .5" accuracy I would think you did these in the exact same way. Trimming the cases would make next to no change in the ballistics. Neither would just cleaning in a walnut chips. Is there a possibility that you had some resizing lubricant inside that made some of the walnut chips stick reducing the case volume? Any changes in your loading procedure? Same bullets? Same overall length?

I screwed up once after annealing some cases, cooling in water, then tumbled them. I though I had given them time to dry but evidently not and was in a hurry. I loaded and fired a few. Several had signs of overpressure when they shouldn't have. After checking some fired and unfired rounds, several had clumps of walnut media stuck in the inside which reduced the internal volume and created a pressure rise. Another lesson learned!

I did have a little build up of fine dust in the neck, most likely because of lube, but I brushed it out. It didn't seem to be past the neck. How would you recommend cleaning the brass after tumbling to ensure that there was no residue stuck in the case?

 

[KMart]

I'll check the mounts and rings when I get home tonight but I don't feel that's the problem.

Check the action screws also. In the last year or so, I replaced the scopes on a couple of rifles for my friends. They bought new ones and I agreed to change them out and sight the rifles back in. In both cases, the action screws were loose and the front ones were being held in by less than a thread.

 

[suasponte]

More evidence supporting my theory that cleaning brass actually harms accuracy. jd

There are so many unknown variables how can you say for 100% that cleaning your brass degrades accuracy. There is no evidence to be had, are you on Robert Mueller's legal team.

 

[suasponte]

Gerald, I respectfully disagree. That level of accuracy drop off is most likely not reloading related. I believe there is a gun/sighting system problem.

Bingo

 

[243winxb]

Was a different component used? A bad , new lot of bullets can change accuracy.

Give every component a lot number. If accuracy changes, you know where to look first.

 

[ireload2]

Compared to dull oxidized brass bright shiny cases will have much less friction when sized. If you use exactly the same die setting with your FL die the case shoulders will be pushed back more than run of the mill oxidized brass.

 

[KylerB]

Was a different component used? A bad , new lot of bullets can change accuracy.

Give every component a lot number. If accuracy changes, you know where to look first.

All bullets and powder were from the same lot.

 

[T-shooter]

I did have a little build up of fine dust in the neck, most likely because of lube, but I brushed it out. It didn't seem to be past the neck. How would you recommend cleaning the brass after tumbling to ensure that there was no residue stuck in the case?

Fine dust probably won't matter. I had clumps of cleaning media coming out of the ones that were wet inside. Q-tips are the best thing to clean and lube with. You could run them all the way in and check to see if anything comes out. I lube the inside of the necks that way with a very light coat of lube. Spraying into the case neck isn't a good idea. If you do need to wash the cases, hot tap water and dish washing liquid works well and let them soak for a couple hours. It usually takes a couple rinses to get them clean afterwards. The shake the excess water out and set them vertically for at least 24 hours to dry, or in an oven on 200° for an hour. CAUTION, wives can get upset using their ovens to dry brass. Best not to tell them!

 

[Martin52]

I did have a little build up of fine dust in the neck, most likely because of lube, but I brushed it out. It didn't seem to be past the neck. How would you recommend cleaning the brass after tumbling to ensure that there was no residue stuck in the case?

If you tumbled the cases after resizing and they had excess lube left on them it is quite possible that some of the crushed walnut shell media has got stuck around and possibly inside the flash hole. I experienced this problem a long time ago after using a lot of lube when neck turning and not getting enough off before tumbling. Ever since I have inspected each case and run a thin piece of dowel around the inside after tumbling and if any residue is found and can't be dislodged I keep a can of compressed air handy to blow it out. Make sure the flash holes are clear.

 

[Zero333]

If you have another known good scope you can put on this rifle that would help verify the optic is or isn't the problem.

 

[Nature Boy]

I've always heard to not de-copper the barrel very often after initial break-in in order to leave the barrel "seasoned."

Copper fouling is not generally good for accuracy. Better to remove it and keep it copper free. "Seasoning" is great for cast iron frying pans but not so much for rifle barrels.

I stick to my opinion that until you can verify and eliminate a chronically fouled barrel, you're just chasing your tail. And, the only way to verify it is with a bore scope.

 

[nmkid]

Do your cases need to be annealed?

 

[mmcu]

I may have missed this in one of the previous posts, but were the loads you developed really capable of consistent 0.5" groups? How many groups did you shoot with these loads? 1, 5, 20?? Three shot, 5 shot or 10 shot groups??

You certainly wouldn't be the first person to be fooled by a load that looked promising during development that turned out to be a "dud" in reality.

Just a thought.

 

[Intheshop]

Assuming a decent load,I wouldn't be questioning that unless some gross oversight?

If general "best practices" are followed regarding scope mounting..... and considering the scopes innards are up to the task.Then it is normally some sort of mechanical failure.

One thing that makes a competition rig is, it's ability to remain in tune taking the action out of the stock.Known,repeatable action screw torque( more complex than most believe) and a "bed" that is also repeatable/predictable.So,while you no doubt will get your rig back to shooting dots,it's the repeatable mechanics that "should" be the goal.Good luck,and please do a follow up once diagnosed.

 

[ebb]

I had a gun go south like you are talking about. Bore scope showed it had 3 pits in the barrel. I some times shot nuisance deer under shade cloth that was fertilized through the irrigation system. I suspect I got some fertilizer in the bore and didn't know it. If you bore scope your gun you may find the answer.

 

[dickn52]

Check out the ta

look at the Crown- maybe the wife got mad at ya'
Just kidding , seriously look at the crown. My accuracy went to hell on a 308 so I checked mine it was ok. Turned out the scope WAS loose.
J

Yes. I recently went to a range and my shots were all over the paper. It was driving me nuts. I reached up and put my hand on top of the scope to steady the gun and voila It shook in every direction. Base was loose. Rings and everything were great, but the dam base had worked loose.

 

[wholman]

I am no expert but if your on one of those real skinny nodes
it mite shoot good today and the next day what the h-ll.