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strange occurance

984 Views 15 Replies 8 Participants Last post by  oddball
My Classic has always shot .500" groups at 50 yds since its 500 round break-in. Now, after 18 months, it has suddenly started acting strangely. She has always liked CCI Standard Velocity. (She likes Wolf Match Target even more, and used to do .375" groups at 50, but I save that stuff for bench matches). The CCI's I have are all the same lot number. Head shots on rabbits was no sweat, and there were very very few blackbirds that lived after my crosshairs landed on them. All of a sudden about a month ago, I started missing. Ok, no problem, punch some paper, I must have bumped something. The groups had opened up to 1.5", with a wandering zero. I broke the gun down, and did a very thorough cleaning. Back to the paper. I am now getting 1.25" groups, with the zero still walking, mostly left and right. I switched scopes, with no improvements. The Wolf ammo falls into .750" groups, but they wander as well. I am going to try a third scope this week. I cannot imagine what is causing this. Any ideas? I have always tightened the action screws as tight as I could get them, and even tried different torque values to no avail. I have tried different brands of ammo and different lot numbers with no benefit. I even tried a pressure point along the barrel in different places. Strangely, that did nothing for the groups -- they stayed the same, just shifted upward a few inches. I believe I have tried everything I have read here, and within my mind. Any ideas and/or suggestions would be greatly appreciated.
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I would suspect the scope, but as you've tried 2, I don't know. What kind are you using? What kind of bases/rings are you using? Are they tight? Just throwing this out there: Is the barrel tight? Does it look like it is rotating or backing out? The Classic barrel is threaded in, wonder if it is slowly rotating out?

Chunckchucker
 

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Oddball,

It might be that something happen inthat the bore was scratched or something. I can't believe that you would have problems with two different scopes. I know someone that had a T/C Classic and his starting to shoot high around 3". Couldn't figure it out why it was doing this, very strange :confused:

DAVID
 

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Discussion Starter · #5 ·
I am using Thompson Center bases. The original scope setup is a Pine Ridge (Cabela's) 3-9x32 Rimfire scope in Weaver rings. The second scope is a Bushnell Sportsman 4-12x40 AO in unknown rings (I borrowed them from a shooting buddy). Everything is tight. I used a fiber optic attachment for my mag lite to inspect the bore, and everything looks perfect, no shadows, no scratches. Action screw torque does not matter to this rifle as I have tried everything from finger tight to as tight as I can get them. When the rifle was new, I used a pair of thin brass sleeves inserted into the action boss holes to "bed" the action, per se. This improved accuracy by roughly 25%. The barrel is not rotating as far as I can see, and I cannot dicern any looseness when the rifle is apart. As an aside, I am having the same problem when using the iron sights, but I hate to use that as any kind of aide for diagnosis since as a rule I do not do well with iron sights.

I would be tempted to send her back to T/C, but not sure what they are going to say about my trigger job. All I did there was lightly stone the engagement surfaces to remove burrs, followed by a polishing.
 

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Discussion Starter · #6 ·
My father is bringing me his good, brass brush when my parents come to visit today. I have never touched this rifle with anything other than a bore snake, and other than the break-in with Mini-Mags, it has never seen copper bullets.
 

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Discussion Starter · #8 ·
Update time. I scrubbed the barrel real well with lead remover and copper remover. The only good quality subsonic ammo I could find locally for now was Federal Classic Gold Medal. I took her out, and ran groups as I fouled the barrel out and sighted in the third scope. Started out with 1.25" groups. I got two groups running about .400", but all the others ran 1.00 to 1.50" none of the groups would stay put. Each group would move either left or right of the prior group. It isn't shaving the bullets. I am just lost, not to mention frustrated.
 

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oddball
I know that a bolt gun will get a lead ring and the accuracy will fall off like you described. The ring, I have been told by someone that started with a clean barrel, and then looked at the barrel after each shot starts forming after as few as 25 rounds. This is the reason you see many BR shooters clean after each target.
Sorry it didn't help--was the conditions ( wind) the same when you were shooting? this can cause the same problem.
Jim :D
 

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Discussion Starter · #11 ·
The crown is good -- I can't see any nicks or gouges, and it looks even. The wind was virtually non-existent -- I know because at 95 degrees and 60% humidity I was miserable. I don't think a lead ring is a problem since it will just randomly throw a good group. The last time I shot, all groups as I said were running between 1.00 and 1.50" (roughly). The first three groups were within this range. The fourth group was roughly .400". The next one was around 1.25, with the sixth being .400". The remaining three groups were 1-1.5. All groups were five shots at 50 yards.

I have that proverbial bitter taste in my mouth.
 

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Sounds like a barrel to stock fit issue. Is there a pattern? Like it shoots good first few shots then opens up when the barrels heats up? That may indicate a change in barrel vibration due to stock touching where it did not before. It could be that the stock swelled up a bit or shrunk and bent causing a different barrel to stock fit. I'd coat the barrel with blue compound stock makers use, or even red lipstick, put it together carefully, tighten it down (perhaps even shoot it) and she if it's hitting stock somewhere.
If you know another Classic owner, try his stock.
 

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oddball,
here's a link to some of my experiences with two of these rifles:
Link
I'd check your bore with a good light and look for shadows, particularly beneath the sight mounting screw holes. Make sure you have no shadowy rings in the bore as well. Seems you've eliminated bedding as a problem, but just for giggles, ensure your action screws are not bottoming out or that the stocks wood hasn't compressed to the point it no longer holds the action securely.
Check the chamber area in the extractor groove, if this is blown out, the extractor can bear continously on the case causing all sorts of bad juju (not to mention the chance of a case rupture in an unsupported area).
How do your fired cases look? Uniform pin strikes? If not check the pin and its raceway. There are so many things to look for (sight unseen) :(
 

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Discussion Starter · #14 ·
obx22, your link doesn't work, directs me to a RFC page stating that the search terms were not found. Otherwise, your suggestions about the extractor groove and firing pin strikes are things I had not thought about. I will be looking into this further tomorrow.
 

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Sorry the link didn't work. Use Advance Search, term "Classic", posting by obx22 and you'll find my past experiences with these rifles. Hope you get her figured out :t
 

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Discussion Starter · #16 ·
I got to looking tonight, and the extractor groove does have a literal groove worn in it, but it is not bad -- yet. The extractor is not touching the chambered round. The bolt does have some side to side play in it. Also, the mounting screws on one side of the trigger group were loose. These are the screws that attach the trigger group to the receiver. I "notched" the threads lightly with pliers to help keep them in place. I cannot see a thing wrong with the barrel. I will be checking fired cases tomorrow night when I go shoot it. Thanks for all the help so far!
 
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