sudden accuracy loss

[scottprice]

My brother has a Lyman Deerstalker and was always able to shoot about 1.5" at 50 yards with 90gr of powder, .490 balls and .005 patches.... Now, for some reason he cant keep it inside 6" at the same distance.

We have tried dropping powder charge to 70, then 80gr, tried .010 patches, .495 balls and different combinations of those changes. I also shot his gun and my groups were the same..

**for comparison, i was shooting clovers at 50 yards with my GPR, so its not the shooter....very confused

any advice?

 

[coloradoclyde]

Assuming that the components are the same as they were and have not been changed....I would begin to inspect the gun...
Do I have unseen fouling in the barrel?
Is there a problem with the sights?
Is my nipple worn out?
Is the barrel sitting in the stock properly?

 

[Dean2]

I agree with CC. Not likely the load. Sounds like something is loose and moving around. Is front and rear site tight, is barrel wedge missing etc.

 

[BrownBear]

I'd go straight to a nipple change before doing anything else. Quickest and cheapest by far. If that doesn't fix it, carry on.

 

[Shifty]

I agree with nipple being #1 thing to check just replace it and go from there ,clean the breech area and fire channel ,check tang screw for tightness,and that factory rear sight too,wedge,just look at every thing.

 

[will5a1]

Inspect the muzzle's crown for damage - has the rifle been dropped muzzle down on a hard surface?

 

[eggwelder]

How does the nipple affect accuracy? just asking, because I have a hawken style that is all over the place, and the nipple was old but useable when I got it.

 

[Jim Evans]

What if its a flintlock and it doesn't have a nipple?
I would try a .015 patch with the .490 ball. maybe a felt pad on top of the powder if the thicker patch does not work.

 

[Artificer]

How does the nipple affect accuracy? just asking, because I have a hawken style that is all over the place, and the nipple was old but useable when I got it.

Nipples get burned out from too many times used. (Heated Gas from the burning powder charge travels both against the projectile and back into the nipple towards the hammer.) That means it won't give a consistent amount and direction of the flame going into the powder charge. That means loss of accuracy. You may see either a gradual loss of accuracy on a nipple that has been used too much OR it may happen suddenly and very noticeably.

I can't begin to remember how many times a new nipple brought accuracy back in NSSA guns and International Target guns. If one shoots a lot of matches/target shooting each year, I always recommend you put a new nipple in at the start of the year and then you won't have to worry about such things for the entire year.

Gus

 

[M. De Land]

Good advice Gus!

 

[BrownBear]

Good points, and fine explanation.

One other consideration: If you're firing lots of hot loads, especially with heavyish conicals, nipple erotion is greatly accelerated. I know several folks so inclined, and they're changing nipples every time they open a new tin of caps. Might be excessive, but they seem to know what they're doing in every other aspect of their shooting.

 

[Artificer]

Good point! Hot loads will definitely wear out a nipple far faster than target loads.

Gus

 

[fleener]

for a hot load, consider a platinum lined nipple.

Fleener

 

[Idaho Ron]

I'd go straight to a nipple change before doing anything else. Quickest and cheapest by far. If that doesn't fix it, carry on.

You took the words right out of my mouth. Solid advice BB. :thumbsup:

 

[Zonie]

My brother has a Lyman Deerstalker and was always able to shoot about 1.5" at 50 yards with 90gr of powder, .490 balls and .005 patches.... Now, for some reason he cant keep it inside 6" at the same distance.

We have tried dropping powder charge to 70, then 80gr, tried .010 patches, .495 balls and different combinations of those changes. I also shot his gun and my groups were the same..

**for comparison, i was shooting clovers at 50 yards with my GPR, so its not the shooter....very confused

any advice?

Somehow, after reading your post, I get the feeling your brothers good shooting and poor shooting with the same components is due to the patches.

If these were "pre-lubed" patches, back when they were new they gave good groups.
After sitting a year or more the lube weakened the material so it's blowing apart when the gun is fired.

I mention this because many years ago I was at a gunstore and noticed some really old "pre-lubricated" patches that still had a price tag on the bag that had to be several years old.

"Ah-Ha!" says I. I'll buy these at bargain prices and be set for a years worth of shooting for darn near nothing.

After shooting several shots at the range without hitting the target, I spent my time picking up fired patches while others were downrange putting up their targets.

Every single "bargain" patch was nothing but shreds and bits of cloth. Not one of them held together.

After pitching my worthless "bargain patches" in the trash and getting out some good patches, my next shots returned to its former good accuracy.

 

[Don Steele]

I'm kinda with Zonie here.
.005 patches...????? Seems REAL thin based on my experience with .490 balls in my 50's.
Especially if they're getting old...you may have totally lost any kind of seal.
Otherwise...as already noted, always check the cheap, easy stuff first. Are the sights TIGHT...??
Is everything else TIGHT. Tang screw,barrel key(s) if present, and anything else that affects the ability of the rifle to give reproducible results.
We had a guy in our match last week who started shooting "wild shots" all of a sudden. His rear sight had gotten so loose you could see it flopping around on the barrel when he moved the rifle.
Otherwise, if there's nothing wrong with the sights and it's a caplock...replace the nipple.
After that, I'd be looking at a good bore scrubbing with something like a piece of a 3M "green wool" pad.
Good Luck...and let us know what solves the problem. :hatsoff:

 

[jackley]

If the last time he shot he was using .490 ball 90 grs. powder and a .005 patch (it is quite thin). and if lube is the same, doesn't say anything about pre lubed or what lube is. If the patches and lube were the same as last time, and he was shooting 1 1/5 groups then and not now. Then the variables would be nipple, crown or fowling.

Jerry

 

[Boomerang]

I don't know if he meant .005" patches or .015". If he was using .005" that would have to be paper thin and I would think would certainly burn through.

 

[Shifty]

He also said he tried .010 patchs and .495 balls with same results.

 

[Boomerang]

Ya, I don't know what he is using for patch material, but .010 is still on the thin side. He needs to check his patches after they have been shot for tares or burn through. :thumbsup: