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I have trouble with this,my 30/30 336 barrel lately seems to have suddenly, after nearly 50 years of good service,seems to have given up the ghost, can't believe
it because my 1893 built in 1900 still shoots acceptable groups.first the 336 seemed to be suddenly sensitive to heating up after about 6 rounds,then shoot successively higher unless cooled,then at 100 yds it totally lost it with a shotgun type group,I checked the scope mounts they were good and the scope also checked out I ran through the adjustment in square grids it was fine.then I cleaned it with ammonia based bore cleaner,no green of any great consequence.i also cleaned it electrolytically ,for 30 min. Again some slightly greyish green liquid no great green though,I then used a chores boy but no real reason for leading I had lead bullets ,but for the fist time ever, shot 5 maybe the rest were jacketeds ,proven handloads, no tumblers or keyholes but a shotgun had a better group is at 100 yds,after this a normal regimen and losso bore cleaner with marvel,normally I would use Kroil and JB,but these are not available due to the covid sit.so I adapt and overcome.no great result I know this bore is clean ,it's not perfect with some small pitting but still way better than my 1893,and that dog still hunts(the rifle still shoots)!I figure ,in my ownership from about 1970-72 at least 100 rds. year-+5000 rds maybe ?I have to shoot it again although I don't see any reason to believe I accomplished much no evident crud to see.the muzzle looks good,but I might brass lap it and if no improvement I will have my friend,a good gunsmith look at it .seems strange I did find a crack in the forearm but doubt that is an issue but I will tend to it before shooting tomorrow. Any advice?
 

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You say about 5,000 rounds? I remember when I was shooting Hi-Power as a matter of course the guys shooting .308 bolt guns were removing their hi-dollar hand made barrels at about the 5,000 round count as they swore that the groups would open up about then.
And, they claimed that as soon as the groups started to open up the barrels would go away rapidly.
Used barrels were as common as used dirt track tires!
Comparing notes we felt that those of us that were shooting chrome lined factory barrels didn't get the super tight groups, but got longer barrel life. A lot of guys felt that some certain brand barrels actually had a measurable round count!
Now, that was with super hot loaded .308 loads which are a bit warmer than .30-30, but maybe there is something to barrels shooting out.
There was a discussion going around the beer cooler after matches that minute changes in headspace could affect accuracy. Not being a machinist, I didn't get into the discussion, except for the beer.
I can vouch for my Poly-Tec M1A1, a chrome lined mil-spec barrel with a bit over 3,500 rounds. Shoots as tight today as it did 25-26 years ago. If only my eyes were as good.....
 

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Strip off the forearm, and mag tube............shoot it off a bench with the bags or rest under the front of the receiver, with NOTHING touching the Barrel..........That should tell you if its the barrel or not............

If you don't start this way, you're just chasing ghosts and shadows..............

Tom
 

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what mike said has much merit, from the little I know about it I've read in multiple places 5000 rounds seems to be the common number for what a rifle barrel life is shooting jacketed bullets.
if nothing else possibly a candidate to send to JES, 32 spl?
 

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I have trouble with this,my 30/30 336 barrel lately seems to have suddenly, after nearly 50 years of good service,seems to have given up the ghost, can't believe
it because my 1893 built in 1900 still shoots acceptable groups.first the 336 seemed to be suddenly sensitive to heating up after about 6 rounds,then shoot successively higher unless cooled,then at 100 yds it totally lost it with a shotgun type group,I checked the scope mounts they were good and the scope also checked out I ran through the adjustment in square grids it was fine.then I cleaned it with ammonia based bore cleaner,no green of any great consequence.i also cleaned it electrolytically ,for 30 min. Again some slightly greyish green liquid no great green though,I then used a chores boy but no real reason for leading I had lead bullets ,but for the fist time ever, shot 5 maybe the rest were jacketeds ,proven handloads, no tumblers or keyholes but a shotgun had a better group is at 100 yds,after this a normal regimen and losso bore cleaner with marvel,normally I would use Kroil and JB,but these are not available due to the covid sit.so I adapt and overcome.no great result I know this bore is clean ,it's not perfect with some small pitting but still way better than my 1893,and that dog still hunts(the rifle still shoots)!I figure ,in my ownership from about 1970-72 at least 100 rds. year-+5000 rds maybe ?I have to shoot it again although I don't see any reason to believe I accomplished much no evident crud to see.the muzzle looks good,but I might brass lap it and if no improvement I will have my friend,a good gunsmith look at it .seems strange I did find a crack in the forearm but doubt that is an issue but I will tend to it before shooting tomorrow. Any advice?
Make sure it isn't your ammo, powder weight, changed primer, temperature change, etc... If the barrel is clean, push a soft lead through and check bore size... have you tightened or loosened any screws, and double check the scope mounts (literally take off, I've played that game before).
 

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Tom,how are you? Believe it or not I actually thought of doing that very thing to get all the "riff-raff" ,so to speak,out of the way ,great minds think alike,what's life without a puzzle?those reloads we talked of were in this rifle but because of this I have not learned anything except they fire! But,the 1895 with the 405 gr.hollow base shot them great.thanks,I'm not convinced it is the barrel yet .
 

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I actually put the scope on because I could not seem to get good groups with the aperture,thought maybe it was my eyes,I also checked repeatability with the scope adj. I don't think it was my eyes now,the gunsmith friend will have a bore
scope.but I may still try another scope too.
 

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If you really like it and it is shot out..TJ’s or Track of The Wolf barrel liner it!
 

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I would try what Tomray suggested before looking at the barrel. If all of a sudden it started stringing shots and poor grouping it could be the stock or fore arm fit. Usually shot out barrels lose accuracy over time.
 

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Is the tang bolt tight ? Yer sure The barrel is clean ? Does it look like a mirror inside when you look through the barrel against a light? If not take and cut a dry strip off a green scrub pad that's used for dishes, fit it through the slot in yer cleaning rod and run it through the bore a few times, what's it look like? :questionmark:
 

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Great suggestions already given, and that's good that you tried cleaning it first. 5,000 rounds is a lot, but a 30wcf is a relatively low pressure cartridge, especially when compared with a 308 Win. I doubt you'd see any appreciable group size differences from barrel wear at that round count, but I could be wrong. Do as Tom suggested and shoot it without the fore-end and magtube and see what happens. I would check the crown for damage as well. You not think you did anything to damage the crown but you never know. Things happen.
 

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You say about 5,000 rounds? I remember when I was shooting Hi-Power as a matter of course the guys shooting .308 bolt guns were removing their hi-dollar hand made barrels at about the 5,000 round count as they swore that the groups would open up about then.
And, they claimed that as soon as the groups started to open up the barrels would go away rapidly.
Used barrels were as common as used dirt track tires!
Comparing notes we felt that those of us that were shooting chrome lined factory barrels didn't get the super tight groups, but got longer barrel life. A lot of guys felt that some certain brand barrels actually had a measurable round count!
Now, that was with super hot loaded .308 loads which are a bit warmer than .30-30, but maybe there is something to barrels shooting out.
There was a discussion going around the beer cooler after matches that minute changes in headspace could affect accuracy. Not being a machinist, I didn't get into the discussion, except for the beer.
I can vouch for my Poly-Tec M1A1, a chrome lined mil-spec barrel with a bit over 3,500 rounds. Shoots as tight today as it did 25-26 years ago. If only my eyes were as good.....
I agree with you as a high power rifle competitor our M1A's would normally be good for about 5000 rds. Head space was typically set at the minimum side but you cannot go too tight on a semi-auto for risk of slam-fires. Typical load was 41.5 of 4895 with a 168 grn Sierra Match King boat tail. Barrels usually running 500 bucks for the heavy air gauged barrel with 6 groove 1 in 10 inch twist rate. Barnett, Hart, Krieger, Douglas Premium grade, Shilen, Criterion----all very good barrels.
 

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Strip off the forearm, and mag tube............shoot it off a bench with the bags or rest under the front of the receiver, with NOTHING touching the Barrel..........That should tell you if its the barrel or not............

If you don't start this way, you're just chasing ghosts and shadows..............

Tom
Good advice----sounds like there is some pressure on the barrel somewhere in the fore end.
 
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"Typical load was 41.5 of 4895 with a 168 grn Sierra Match King boat tail. "
Cowboy, That was my favorite load!! I rolled up so many of them I think I could do it in my sleep!

Dave Wilson and I always wanted to unscrew the factory barrel out of my Poly-Tec to see if we could install one of his used Kriegers, but we never had the nerve.
That Chinese clone was just average with me behind it, but it shot 25-35 points better with Dave behind it. Just knowing the technique isn't enough, it takes some talent as well.
 
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"Typical load was 41.5 of 4895 with a 168 grn Sierra Match King boat tail. "
Cowboy, That was my favorite load!! I rolled up so many of them I think I could do it in my sleep!

Dave Wilson and I always wanted to unscrew the factory barrel out of my Poly-Tec to see if we could install one of his used Kriegers, but we never had the nerve.
That Chinese clone was just average with me behind it, but it shot 25-35 points better with Dave behind it. Just knowing the technique isn't enough, it takes some talent as well.
Holy smokes!!! That’s about ten grains over max with a 170 grain bullet! You are going to blow your marlin to smithereens. And a pointed bullet in a tubular magazine??? Wow!


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Holy smokes!!! That’s about ten grains over max with a 170 grain bullet! You are going to blow your marlin to smithereens. And a pointed bullet in a tubular magazine??? Wow!


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They're talking 308win, and since we're on the topic of it, that was a favorite load of mine for a long time in my Cooper until I went to VV140.
 

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Sorry, I was impression that this thread was about a gentleman who had a marlin 30-30 that had developed accuracy problems. I did not notice we had moved on to different rifles and different calibers.


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Don't discount that crack in the forearm. Do as Tomray says. I have had cracked stocks before and was surprised at the change in zero. Glued them up and group size shrunk.

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