loss of accuracy after several hundred shots?

[LH]

I started shooting a new barrel last winter.  After patch/ball testing with a scope glued on,  I found a load that was veryVERY accurate. Like ten shot groups at 100yds in the 2.5" and sometimes better range. (when the wind wasn't blowing)  I didn't just shoot that load a few times with the scope either.  Probably on 6 or 8 consecutive days with the same results.  I shot this gun all spring in several  matches with fantastic results.  All the matches were offhand and I shot some of the best scores I have ever shot with it. Always able to call my shots to nearly nothing.  I could not shoot for a couple of months (June and July) and when I went back to practicing for Friendship two weeks ago,  I started getting wild shots on a regular basis.  I glued the scope back on after a few days and my groups are now in the 6" to 8" range.  The gun was stored with the same light machine oil I use in all my guns and has never seen a speck of rust.  Sights are not moving,  something has happened to the bore I believe just from shooting several hundred rounds.  I have seen this before with another brand of barrel, and once before with a barrel of the same manufacture as this one.  In the past I have "cured" it by very aggressive polishing with lapping compound on cloth patches and a lot of elbow grease.  I have no idea what the culprit is though and am wondering if any of yall have encountered this.  ?  thanks.

[bob in the woods]

What powder are you using, and the rifle flint or percussion ?   Is it a full stock ?  How is the barrel fit in the stock. After storage, I would suspect the stock to change over the barrel. That said, my experience has been that the barrels smooth out , but I haven't had any loss of accuracy until after thousands of rounds, not hundreds. I found an increase in powder charge ..even 5 grains or so cures the problem.  Worth a try.

[Old Salt]

Are you using the same patch material you used when you had the good accuracy? if you are you may want to try some slightly thicker patching material.

Old Salt

[Mike Brooks]

Check to see if the barrel lugs are slotted. Sounds like a change in humidity has something in a bind.

[T*O*F]

If it's a percussion, your nipple might be blown.  Try replacing it.  On a long range rifle, this can happen in as little as 10 shots if the nipple isn't platinum lined, however longer on a round ball gun.

[Flint62Smoothie]

Anytime I’ve seen this it was from TOO MUCH lube build up in the bore, most cases w/ soft lube like ... ick, ‘bore butter’. Cleaning the bore well w/ hot water and J&B Bore Polish restored the accuracy.

[Roger B]

Check all of the variables the guys have mentioned and if nothing else, glass bed the barrel to stabilize the inlet. I've done that a couple of times in a similar situations with good results. A sudden change like that almost has to be stock. I've seen barrel crowns wear unevenly, but that is usually a more gradual process.
Roger B.

[bgf]

Good suggestions.  I'd start with a good cleaning and new nipple or touch hole, as neither of those have a downside.  When I shot grease or oil based lubes (including Murphy's oil soap) I often saw buildup in grooves after a while even with good cleaning.  Usually some work with green scrub pad on undersized jag with optional polishing compound would clear it up, though I have also used heavy duty oven cleaner (with lye) or even lye water to get the stuff out.  Even though I wipe the wd40 off before I shoot and use water only patch lube, it seems like it will sometimes build up as well.  That's why I include alcohol and acetone in my cleaning regimen.  I started using a group of detergent in my first bucket of water also, and that seems to help.

When I was shooting 1000s of shots per year between practice and matches, it seemed like I was regularly using extreme measures . I

Good luck!  One thing I've found as well that can be infuriating is that a different lot of powder or new patching can be inferior to previous. 

[Hungry Horse]

Here’s a couple of possibilities that have’t been put forward. Your patching may have degraded over time. Cotton is notorious for this. Check your shot patches for damage. Modern lubes often have ingredients that have no business in your barrel. And manufacturers often change these ingredients when one, or more, becomes hard to get. I use venison tallow, and, or bear grease. Mutton tallow is available commercially, and works well also. I melt the lube, and dip the precut patches in it, so there are no lumps, clumps, or blobs of lube.
 Oh, and lose all the caustic stuff you’re poking down your barrel. If you use natural, period correct lubes you won’t need them.

 Hungry Horse

[hanshi]

So many causes to investigate!  If I had to guess I guess at the stock acquiring some dimensional changes.  Some lubes are just destined to cause bore buildup.  There's no way the barrel could be worn out by now.

[David Price]

If your rifle is a flintlock my first guess would be the touch hole is burned out.  Some of the touch hole liners that are available are not very hard.  If it  has opened up on you  some of the powder could be leaking out when you drive the ball down resulting in shooting a different charge every time.    It is easy to check, remove your flint stone first, close your frizzen and load the rifle.  This is rather dangerous so be very careful. Once it is loaded open the frizzen and check if there is any powder in the pan.  If there is powder in the pan you have found your problem.

David Price

[One Eye]

With the solvents you are using you might want to make sure your cleaning patches are pure cotton.
Some of the so called arsenal patches have polyester in them and the acetone may be melting that stuff in your barrel.
HTH,

One Eye

[smokinbuck]

I know you have received a lot of good advice regarding your problem but I had the same experience this past weekend. I shoot table with an underhammer and put a new nipple in at Friendship in June. I've fired maybe 100 shots between then and  now, which you wouldn't do much damage. My group went all to $#*! and my nipple was burned out that quickly.ck of things. It can sometimes be the least expected  I changed the nipple and got back into the thick of things. Sometimes things don't make sense but they happen.
Mark

[moleeyes36]

I can't remember the last time I even shot a percussion rifle, but when I still shot them I found the Spitfire Magnum Nipple to work best for me and last a long time before needing replacement.  Worth a try.  http://www.cainsoutdoor.com/shop/product.asp?c=0&l=Nipples+-+Spitfire

Mole Eyes

[hanshi]

Spitfire nipples are exceptional.  I've used them in the past; and have one on my only percussion rifle - except for my US 1841 which requires a musket nipple.

[bob in the woods]

Let's see if the original poster gets back with some feed back .....