I have a 1895 marlin .44 mag
It was given to me by my brother in 1980 when I was 15. It was my first and only deer rifle until a few years ago. I killed my first deer with it and many, many more since.
It has the micro groove barrel and has suddenly gone from a tack driver to a bullet slinger. I have been told that shooting cast bullets through it will cause this.(leading) I think that I did shoot some cast reloads through it a few years ago. Could this be the problem? I have cleaned it well(perhaps not well enough)
I really am attached to the gun and want to pass it on to my own sons someday, but not if it's a poor shooter. Is there a method to ensure no lead is in the barrel, should I assume that I have worn it out and send it to the factory for reworking, or get a new one? Suggestions?

Well, if you're going to throw it out, throw it my way! I once had one but it was a victim of the big D and somebody else has it. I loved mine. It was more dependable than the wife!

Seriously, I don't think that shooting the lead bullets did this, more likely is that a screw is loose. I'd check that first. Make certain all the screws are tight. IF you have a scope or receiver sight mounted be especially certain to check those screws first...

Also, IF you've been cleaning from the muzzle end (not required with the Marlins) then you might have damaged the crown yourself... It is a simple matter to fix that if necessary. If you can see any damage there (and don't assume because you take care of it, somebody else hasn't gotten their mitts on it somehow. )then go back and reclean the rifle's bore.

My bet is that it is one of these 2 things. I seriously doubt you've shot it enough to wear out the bore or the gun.

However, being a good buddy to all I meet, I'm willing to make a sacrifice and take it off your hands...

I go along with Hobie. Check all the screws first.
Then, while I doubt that leading is the problem, get a Chore Boy scouring pad, (I think that's the one without soap. You want the the one without soap.) Pull strands off the pad and wrap it around a tight (AKA new) brush and scrub the holy livin' bejabbers out of the barrel. (Actually, it doesn't take a whole lot of scrubbing.) Third, inspect the muzzle for cleaning rod wear. If that is the case, you'll have to have the muzzle counterbored to get past the wear or rebarrel the rifle.
That's the thing I dislike about the Micro-groove barrels. It doesn't take much to mess them up, especially in 30 caliber. Hopefully, it's not a barrel wear problem. let us know how it works out.
Paul B.

Thanks for the info.
I will try the cleaning/ crown inspection route. I hope I haven't damaged the crown.
Hobie,
sorry about your gun, congratulations on your divorce and even if it would be better served as a boat anchor I will just put my .44 on a display over the fireplace, it has been that good of a gun.

Actually leading can have a negitive on jacketed bullet...Clean the gun and I mean clean the gun, my favorite is Kroil and JB compound, followed by liberal doses of Wipeout to get any copper fouling out....

Yes, check all the screws and be sure no warpage in the wood has occrured and that the stock is tight to the action...

I seriouly doubt that you can shoot a barrel out at the velocity your getting out of a 44 magnum, at least not in a lifetime....check for rust in the bore....Might need a gunsmith to look it over.

Good news,
I cleaned the rifle 3 times spread over about a week. Tightened all the screws.

I shot it yesterday, iron sights at about 45 yards. The target was a bullseye the size of a nickle. (could hardly make it out) Four rounds went down range and four rounds stayed within the circle, looked like a four leaf clover. I wasn't even sandbagged, just propped against a tree. This is the way it used to shoot and I can't tell you how glad I am.
I wonder if I can take this thing to Africa for some close range smallish game-it's practically a member of the family.
Thanks.