Author Topic: Point of impact change  (Read 8662 times)

Offline varsity07840

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Point of impact change
« on: October 13, 2008, 03:36:49 PM »
I own an original Westley Richards percussion stalking rifle that I shoot occasionally and thought about hunting with this year. Before I ask my question, here are some specifics on the rifle.

16 bore, 30 inch barrel, 10 narrow lands and grooves twist around 1/60
Rough but shootable bore, fouls easily as a result.
Patent breech with platinum vent.
Very light weight, 1.1 inch breech, tapered barrel, heavy recoil off the bench
Groups ok for hunting at 50 yards(about my limit with open sights)

Ok here goes. With 75 gr of 2F Swiss and a patched ball, it was shooting about an inch low at 50 yards. The front sight is very low. I tried upping the charge to 85 gr, with little to no change in elevation. Then after a few more shots, the groups dropped about 6 inches without any sights change! Occasionally I got one shot up where they were before. As I said, the rilfe is a real thumper off the bench, so after around 20 shots I packed it in. I can't figure out what caused the drop. I checked the breech area before cleaning and I can't see any signs of leakage. Could it be the way I'm resting it on the bench. The sights and my eyes don't agree, and  to keep it as steady as possible I had it in a vise type rest that I eventually tightened up on the rifle and bore down on it more than when I started.  Could that make a difference in muzzle jump? Too much venting? The barrel and breechplug were disassembled and checked out by Ken Owen and found to be in good shape after I bought it.

Opinions/suggestions will be appreciated.

Thanks,

Duane

chapmans

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Re: Point of impact change
« Reply #1 on: October 13, 2008, 04:13:13 PM »
Duane,
    Welcome to the board!!  I can think of a few things that may be causing problems.
   Was there a change in the light conditions? This will cause a change in elevation but I have not seen that big of a change, usually only an inch or so.
  Did the barrel get hot? This will usually cause shots to go all over the place not just low.
Were you holding the gun differently maybe a tighter grip in anticipation of the recoil? I know from shooting x-sticks you have to use the same grip pressure or the impact will change but not 6 inches but from a 10 to a 9, again maybe an inch.
 Did you concentrate on the sight picture every time, was it the same every time?
  Was there any mirage with the heat coming off of the barrel?
Did you check the nipple when a nipple goes bad things go bad in a hurry!
 How about the vent, I know some percussion guns were vented, did the hole become enlarged?
 Are the barrel wedges (keys) tight? or does it have pins.
               These are just some things to watch for, I'm sure others will have some different ideas.
    Regards, Steve C. 

 I just reread your post and noted you were using a vise type rest, this may also cause a problem because the rifle can't recoil the same each time.  
« Last Edit: October 13, 2008, 04:18:46 PM by chapmans »

Levy

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Re: Point of impact change
« Reply #2 on: October 13, 2008, 04:46:45 PM »
It's a large bore gun with a lot of recoil.  Recoil starts before the bullet leaves the bore and you held it down to make it more steady.  I'll bet that if you go back to shooting the gun without the vise, the impact point will move up on the target.  If you shoot it from the shoulder, it may shoot higher still.

James Levy 

Offline Roger Fisher

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Re: Point of impact change
« Reply #3 on: October 13, 2008, 06:17:11 PM »
It's a large bore gun with a lot of recoil.  Recoil starts before the bullet leaves the bore and you held it down to make it more steady.  I'll bet that if you go back to shooting the gun without the vise, the impact point will move up on the target.  If you shoot it from the shoulder, it may shoot higher still.

James Levy 
Ol Jim may have the answer!!..   Another possible cause for this change after you shoot several shots at the same 'sitting', If that barrel has a hard/tight spot in her that she warps a bit as she warms up could cause the change in impact (up down or sideways depending on that tight/hard spot)  I had a barrel yrs ago that as she warmed up she moved the ball gradually up and off the paper on that double bull buffalo at 50 yds from a rest.  'We', sluggged that barrel and found an ultra tight spot back abt 11 in or some such from the muzzle.  Had to hammer the lead lap past that spot.  Ended up getting rid of that barrel (she ended up cut back and put on a short barrel hunting rifle.

I seem to recall she was a 45 in abt 40 in length straight 15/16th, 

So this could also be the problem ::)  Let us know how it goes.

keweenaw

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Re: Point of impact change
« Reply #4 on: October 13, 2008, 07:19:18 PM »
I think all the possible causes of change in elevation have been mentioned.  I'd look closely at the nipple to make sure it isn't enlarged.  85 gr. would have been a much heavier load than would have originally been used in the rifle.  I'd stick to 60 to 65 grains. of Swiss. Those light rifles were designed for close shooting and at 50 to 75 yards and inch or two in elevation makes no difference whatsoever. That big ball will have plenty of energy to kill a deer even at the lower velocity.  Given that your rifle is in good condition and you want to use it, I strongly recommend you get the barrel lapped to get rid of most of the roughness.  My rifles with rough barrels, in addition to fouling badly, get very unpredictable after a few shots.  Because you need to really hold onto a light rifle like that try using just a front sand bag, hold the forearm in your hand and rest the back of your hand on the bag.  Definitely don't shoot it in a vise.  That stock is pretty thin and light and the heavy recoil might end up doing serious damage to the stock. 

Tom

BrownBear

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Re: Point of impact change
« Reply #5 on: October 13, 2008, 07:29:44 PM »
I had it in a vise type rest that I eventually tightened up on the rifle and bore down on it more than when I started. 

There's the answer based on my long experience as a cartridge benchrest shooter and longrange handgunner.  In either of those venues changes in your rest can really move POI, in the same way that inconsistencies in technique will cause a group to grow.

I find the same to be true with MLs, and probably concentrate as much on consistent bench technique as I do sight picture.  If the gun is thumping you and you're trying to get around that while sighting in, try what I do when benching my real kickers- 375 H&H, 458 Winchester, 416 Rigby and 460 Weatherby.  Shoot upright from a high rest and put a 25 pound bag of lead shot between you and the butt, but don't clamp down that rifle.

Offline varsity07840

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Re: Point of impact change
« Reply #6 on: October 13, 2008, 09:15:51 PM »
Thanks to all for the feedback!

Tom, regarding the powder charge, you're right. I will definately drop it down. I thinking of sending the barrel out to Bob Hoyt to clean it up.

Daryl

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Re: Point of impact change
« Reply #7 on: October 14, 2008, 08:07:22 PM »
I'd just go to work on the bore with a lead lapp and different compounds to get it smooth again, then repeat the tests. Cool rifle.

Offline varsity07840

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Re: Point of impact change
« Reply #8 on: December 02, 2008, 04:14:02 PM »
I'd just go to work on the bore with a lead lapp and different compounds to get it smooth again, then repeat the tests. Cool rifle.

UPDATE!!!!!

Yesterday was opening day of early muzzleloader here in NJ. Took a 6 pointer with the old gal.

65 gr. 2F Swiss
16 ga  Cushion wad
.625 ball with .022 mink oil patch
ONE AND DONE!!

I did some lapping with some compound on a VFG brass fiber/felt scrubber from Brownells. They work very well. The bore still needs work but does load smoother. The last range session before the season proved that the point of impaqct problem was indeed the way the rifle was rested. The rifle is dead on at 50 yds and groups pretty well for an 1830s vintage rifle. Thanks to all for the advice!

Duane



Offline Collector

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Re: Point of impact change
« Reply #9 on: December 02, 2008, 05:04:42 PM »
Sir, Out of curiosity (plus I like 16 bores) what does your barrel mike to?  "ONE AND DONE," - I like that one.  :)  Thanks in advance for your time and reply.

Offline varsity07840

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Re: Point of impact change
« Reply #10 on: December 02, 2008, 05:52:58 PM »
Sir, Out of curiosity (plus I like 16 bores) what does your barrel mike to?  "ONE AND DONE," - I like that one.  :)  Thanks in advance for your time and reply.

As best as I can remember, a bit under .650, which technically I suppose means it's a 17 bore. I took it to Ray Rapine a number of years ago to find a mould for it and he refered to it as a 16 and I took it from there. Recently I thought about trying a bigger ball size, since I discovered that I could get one from NEI, but with the less than perfect bore, I like the idea of the thick patch. Now that I've taken a buck with it, it'll go back on the rack for a while.

Next year I plan on using a 14 bore(.687) original with a massive barrel. 
1 5/16" thick, no taper, 30" long. It's sidelined now while I find another Goulcher lock for it. It has a very slow twist for roundball which shoot well, but it's incredible with a Rapine semi wadcutter 500 gr. minie that I normally use in my 1842 rifled musket. I thought heavy charges would deform the skirt, but with 120 gr of 2F they all touch at 50 yards and at the same elevation as a round ball. I'm also still working on the best ball/patch combo.

Duane


Daryl

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Re: Point of impact change
« Reply #11 on: December 02, 2008, 08:00:56 PM »
Duane - I sure like the sounds of your 'originals'. They are hunting rifles - 'course my 14 bore shot well enough for target work and was difficult to beat.
 Holding the rifle exactly the same each shot is essential for good grouping, especially with heavy kickers.  The use of lead sleds and other shooting 'helpers' is very hard on the stock if the shoulder isn't the only thing behind the butt plate.  I have some shoulder problem now with torn cartilage, so I use a mangum recoil pad underneath my coat when shooting something that hurts. That takes out all the sting and I'm able to concentrate on sight picture and trigger squeeze.

 I thought I needed a slug for a fast second shot, so we (Taylor and I) cut a mould from an old unused one. We used the .6875" drill, ground the tip into a hemisphere and plunge-cut the new cavity. Due to the nominal size of the bullet, I plunger was easy to make - a section of drill.  The mould we made turned out a slightly undersized bullet, so I rolled the pure lead slugs on a doubled towel with a very coarse wood rasp. This cuts into then raises the diameter a few thousandths. These bullets then fit with a couple thou interference fit - ie: rifling engraved upon loading.  I coated the bullets in 60% beeswax/40% Vaseline lube for perfect performance. Kick - oh you bet it kicked, but out to 60 yards, held the same elevation as round balls. The lightest bullet this mould would cast is about 560gr. - then on up to 1,200gr. Too much of a bad thing.

I then wanted nothing to do with slugs and experimented with paper ctgs. similar to the military ctgs. of the 19th century.  I made a tapered plug to roll the printing paper on, making a tapered tube. The reason for the taper is ease of handling and when biting off the small end, little or no power is lost.  The small end is then shoved down into the bore. By the time you get the rod out of the pipes, the powder has dribbled down into the breech. The 'snug' fitting ctg. is then rammed down on top of the powder. The paper ctg. wads up beneath the ball and seals the powder gasses behind the ball.  I found with the snug paper ctg. that accuracy was identical to cloth patched balls- ie: 1 1/2' at 100 meters off the bags. None of the paper ctg.s caught fire nor smoldered on the ground after being fired. All my paper ctgs. had 165gr. 2F GOEX in them - no fires but excellent accuracy. I used WW alloy balls for the ctgs.  In pure lead, the balls for the 14 bore weighed 482gr., while the WW balls weighed 466gr.

 Jeff Tanner of the UK makes excellent round ball moulds of any size you want. They fit regular handles & have no sprue cutters. For snipping off the sprues, I use wire strippers, the plyer's type with little holes for different sized wire.  They snip off the sprues leaving a tiny tit. This is easily rasped off with one swipe, leaving a ball with no sprue - this is handy for hunting as there is no orientation needed of a normal ball's sprue.

 Hope this helps.

Offline varsity07840

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Re: Point of impact change
« Reply #12 on: December 03, 2008, 12:06:20 AM »
Daryl:

PRETTY NEAT!! In my rifle, I"ve tried .672 and .678 balls with various patches. The rifling is shallow, so with the larger ball a .010 loads th best without having to really pound, especially when reloading. Actually, I think I might need more than 120 gr. to get the best groups out of it with round ball, with the slow twist which I believe is around 1/90. After I get a lock for it, I plan to spend some quality time with it this spring, as long as my shoulder holds out!!

Duane

Daryl

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Re: Point of impact change
« Reply #13 on: December 03, 2008, 07:06:23 PM »
Duane - you might even try a .662" 916 bore) ball mould with the shallow, slow rifling.  This will allow at least a .025" patch. You could buy a bag of 25 balls this size from Track to try out.  I prefer thicker patches with the right sized ball - easier loading and hold more lube.  The only use I can think of for a .010" patch would be to double it and use it for cleaning or maybe narrow and tight places on the lock's springs.
« Last Edit: December 03, 2008, 07:06:43 PM by Daryl »

Offline varsity07840

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Re: Point of impact change
« Reply #14 on: December 03, 2008, 08:48:10 PM »
Duane - you might even try a .662" 916 bore) ball mould with the shallow, slow rifling.  This will allow at least a .025" patch. You could buy a bag of 25 balls this size from Track to try out.  I prefer thicker patches with the right sized ball - easier loading and hold more lube.  The only use I can think of for a .010" patch would be to double it and use it for cleaning or maybe narrow and tight places on the lock's springs.

Daryl:

Point well taken. That's the path I've taken with the 16 bore. Ordinarilly, that .625 ball would be considered small.

Duane

Daryl

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Re: Point of impact change
« Reply #15 on: December 04, 2008, 07:56:48 PM »
Way back when we were shooting TC's, with their .004" or shallower rifling (Bro's was .003" deep and a buddie's .50 had .002" rifling), we went the other way. We used balls .005" under bore size PLUs a .022" denim patch (12 ounce). The muzzles were crowned in a very smooth radius which allowed loading such tight combinations.  It was due to the tightness of the ball/patch that we achieved descent acuracy.  Anything thinner shot poorly. Too, the 48" twist taxes the combination and required the balland patch to be tight.  The shallow rifling is what caused me to re-bound in beliefs and I went a bit overboard thinking rifling had to be .020" or more deep. I now know it's the combination of the rate of twist and depth that regulates what is needed.  Only experimentation can teach what is needed - to satisfy the requirements of the shooter, whatever they may be.
 Although the rifling is relatively shallow in your barrels, the rates of twist are slow enough to not require the extremely tight combinations we had to use.  One can then use a smaller ball and heavier patch - easy loading and good lubrication - wonderful combination!