Author Topic: 100 yd deviation  (Read 9946 times)

gdk

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100 yd deviation
« on: July 17, 2010, 12:34:58 AM »
I just built an Issiac Haines, 50 cal Rice match grade  swamped barrel. At both 25yds and 50 yds with 50 mgrains of FFg the point of impact is the same. At 100yds with 80 grains the ball hits 6 inches to the right every shot. If I sight  dead center at 100yds it shoots to the left at 25 and 50. Any ideas would be greatly appreciated.

Gary

Offline Don Getz

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Re: 100 yd deviation
« Reply #1 on: July 17, 2010, 01:30:21 AM »
Gary......it would appear that 80 grains of FF makes the gun shoot to the right.    Why not back off to the good load that
shoots great at 25 and 50, then see where that hits at 100.   It will probably be low, but, so what.....hold accordingly to
hit the center of the target..............Don

northmn

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Re: 100 yd deviation
« Reply #2 on: July 17, 2010, 02:44:02 PM »
I had a rifle that would do that, but it was a Douglas that had runout such that even though I put the Douglas name down it still shot off.  The best you can do is to try to find a load, as Don suggested that would maybe group to the center. Go up in 10 grain intervals from the 50 grain load.  As it is a Very expensive barrel, I would be rather upset about the situation.  Any barrel worth a darn in 50 should shoot with either load with very little fuss.

DP

Scott Semmel

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Re: 100 yd deviation
« Reply #3 on: July 17, 2010, 04:02:46 PM »
Are you shooting with a little no wind? I don't sight in at 100yds unless it is dead calm at the range.

Offline Standing Bear

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Re: 100 yd deviation
« Reply #4 on: July 17, 2010, 04:29:34 PM »
It sounds like barrel run out.  A condition where the bore is not parallel to the flats on the rifle.  As mentioned earlier, the norm for ML barrel makers is to identify run out and mark a flat with their brand to orient the run out on the vertical plane.  Builders then breech the barrel to place the flat with the maker's mark on the bottom or even top.  A barrel with run out in the horizontal plane will group increasingly further to one side as the range increases.  Bill Large barrels are an exception.

If barrel run out is the problem and the gun is sighted in at 25, you should see a slight shift to the right at 50.   The shift at 100 is more pronounced.

I can think of no other explanation for the shift in impact.

TC
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Daryl

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Re: 100 yd deviation
« Reply #5 on: July 17, 2010, 05:43:14 PM »
6" is a lot of divergence in 50 yards.  I am at a loss as to the reason why - except for a fault in the barrel.
A slow twist .50 shouold shoot in line with up to 120gr. 2F.  I cannot see a reason for shooting 50gr. in a .50, unless all the targets are closer than 30 yards or for a women or child who wanted to try my rifle.  In the small calibres, I usually use one powder charge for all ranges and that will be a charge that gives a nice flat trajectory and the 'best' accuracy at 50 to 100 yards. For example, Taylor's .50 Rice barrel seems to shoot OK with 85gr. 2F for close range shooting to 500 yards. My .45 also shoots 85gr. 2F and my .40 shoots 75gr. 2F.  These rifle's 3F loads are 10 to 15gr. lower than the 2F loads.  These are for using an oil or grease for lube.  The extra velocity is required to make them shoot due to the slickness of the lube- I assume. With a water based lube, I can get away with a reduction to 65gr.2F in the .45 and 55gr.2F in the .40.

I have never seen a gun that would produce anything close to accuracy at 50 yards and beyond with such a light load.

Offline SCLoyalist

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Re: 100 yd deviation
« Reply #6 on: July 17, 2010, 05:44:36 PM »
The gun hits to the left at 25 and 50 yds with a 50 grain charge, but to the right at 100 yds with an 80 gr charge?   Glad you got that problem and not me!

I'd say, take a deep breath, clear your mind, and start all over.  Weigh out a couple dozen roundballs so you know they're within a grain of each other in weight.   Shoot 3 shots off a rest at 25 yds with 50 gr, then 3 shots off rest at 50 yds w/ 50 gr, then  3 shots with 50 gr at 100.  Center hold for all shots.   Label  the holes.    Bump the charge to 80 grains and repeat.   Maybe even repeat the test with an intermediate charge, maybe 65 grains.  Using the same charge and hold at all three ranges will give you a hardcopy record of how the ball is moving R/L and U/D with range.

Recover a few patches and examine for any signs of them getting blown or burned.  Anything suspicious,  try different patching or lube.  Or, try 50 gr by volume of Cream of wheat between powder and patched ball.   You're looking for something that will make a difference - find it and you can maybe figure out why it makes a difference and  fix it.

Don't know what you'll see, but some pattern may present itself.  If nothing else, you'll  have some organized data on paper you could scan and send to Rice Barrel Co to see if they can suggest something.

Good luck, SCL

Daryl

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Re: 100 yd deviation
« Reply #7 on: July 17, 2010, 06:37:27 PM »
Further - it doesn't take much wind at all to move the ball 6" at 100 yards.

northmn

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Re: 100 yd deviation
« Reply #8 on: July 17, 2010, 07:34:08 PM »
If it shoots to one side at close range and to the other at longer range you either have a bent barrel or runnout.  I would suggest runout.  I do not know what the warranty is on that barrel but you must have paid about $100 more for it than a Coleraine or Green Mountain and it is "match grade"  There should be no runout on that quality of barrel. I would be slightly upset about this. Even Douglas had a XX where runout was very minimized.  When I had that problem I sighted in for 50 yards, but mine would not shoot quite that far off at 100 yards.  An Isaac Haines barrel has a very thin waist, but I do not think that would do it.  While 50 grains in a 50 is a nice target load with 3f it gets kind of weak with 2f.  My 50 percussion and piles of 50's I have seen at shooting matches all would handle 80 grains of 2f pretty well.

DP

Candle Snuffer

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Re: 100 yd deviation
« Reply #9 on: July 18, 2010, 12:22:35 AM »
I would suggest that you check to see if you have your swamped barrel fitted correctly to the channel, as well as making sure that you have allowed for expansion of the wood when the barrel heats up - by this I mean that your under lug pin holes should have a slight oval (east to west) to allow for heat expansion in the stock.

Personally I think these are the two areas where you will fined the problem.  There must be an exactness of the barrel to stock fit for any rifle to perform correctly.  Though it could happen - I can't really imagine Rice turning out a faulty barrel.

Nothing personal, but 99% of these problems lay with the builder, not the parts.

Offline bob in the woods

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Re: 100 yd deviation
« Reply #10 on: July 18, 2010, 06:40:39 AM »
First, I would check to see if the barrel might be bent, as the lighter swamped barrels can be bent during shipping, [ the B weight .50 is pretty narrow at the waist]  I've it happen to 2. Then check the pins and lugs as per the previous post. Personally, I think that is where you'll find your problem.

roundball

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Re: 100 yd deviation
« Reply #11 on: July 18, 2010, 04:49:43 PM »
Could be other things not even equipment oriented...wind drift was already mentioned, plus 100 yards is a long way for precision with iron sights...and lighting could be at play needing only to be off an eyelash to affect a 100yd POI.

Offline Dr. Tim-Boone

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Re: 100 yd deviation
« Reply #12 on: July 18, 2010, 10:26:43 PM »
How does it print with 80 grains at 25 and 50 yds??
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Offline bgf

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Re: 100 yd deviation
« Reply #13 on: July 19, 2010, 02:26:45 AM »
I'm still not really clear on what's going on.  It sounds like the 80gr. charge simply makes the rifle shoot to the right of where the 50 gr. charge does.  This wouldn't surprise me at all, since there is a significant difference in velocity and spin on the ball between the two charges -- POI can shift sideways just as easily as up or down with that type of change.  As already suggested (I believe), I would set sights with 80gr. charge at 25 yards and then test 50 and 100.  If everything is OK, 80gr. would be my charge.  You could also do the same thing with the 50 gr. charge, but that is a marginal load for a .50 with 1:70 twist in my limited experience and it may not be good at 100; I'm a little surprised it apparently works well at 50.

Offline smylee grouch

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Re: 100 yd deviation
« Reply #14 on: July 19, 2010, 04:37:13 AM »
You might also want to check to see if you are canting on the 100 yd shots as compared to the 50 yd. This could make a difference too.     Gary

Daryl

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Re: 100 yd deviation
« Reply #15 on: July 19, 2010, 04:24:20 PM »
but that is a marginal load for a .50 with 1:70 twist in my limited experience and it may not be good at 100; I'm a little surprised it apparently works well at 50.

Me too.  Flabergasted is more like it.  Too - it depends a great deal on what is considered 'works well'.

Offline Roger Fisher

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Re: 100 yd deviation
« Reply #16 on: July 19, 2010, 05:25:52 PM »
I'm again confused..   But a possible reason (one of several) could be a hard spot in that barrel that warps as she gets warm?

Been there!

Offline KNeilson

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Re: 100 yd deviation
« Reply #17 on: July 23, 2010, 03:42:04 AM »
Ive been watching this thread with interest as it describes the exact same problem I have been having with the exception my rifle shoots to the left as opposed to the right. My sights look horrible as they are offset so much it looks awkward. So---- I did some searching thru the archives on bent barrels and straightening, also googled the subject and found this page describing the optical methods of checking for straightness.
http://books.google.ca/books?id=eDZJAAAAYAAJ&pg=PA292&dq=Straightening+a+rifle+barrel&hl=en&ei=AI5HTKWWJZOinQeTjt2GBA&sa=X&oi=book_result&ct=result&resnum=8&ved=0CFQQ6AEwBw#v=onepage&q=Straightening%20a%20rifle%20barrel&f=false
Using a LED penlight, I could look down the bore of my rifle and see a distinct pattern of rings, the closer my eye, the more rings. One problem, the center of the rings were all offset to the side as in attached image 1. While looking down the bore I then gripped the forestock/barrel and tried to bend the whole assembly by hand and could see right away that I could move the reflected images very easily and center them. So I took the barrel out of the stock, gripped the breech in the vice, put a dial  indicator on the muzzle and moved with one finger till the reflections aligned. It took .095 in.. So now knowing the high spot, I gripped the muzzle and pulled on the barrel, nothing, pulled a bit harder, still nothing. Pulled a bit more (8-10 in) and it starts to move. Kept at it and  after bout 1/2 hour I had the rings alligned. At this point I noticed the barrel tenons were in alignment , where they had a jog in them before. So now thinking Ive straightened the barrel, I move my sights to the ctr of the flats and head to the range... 5 shots each, at 25, 50, and 100 yds I now have all my groups lined up in a vertical plane 3/4 in right of ctr... I`m quite happy......  The barrel is a Rice, 38 in. B weight , swamped in .54 caliber. I`m using 10 oz denim(.018)patch, home brew wax/oil lube with a .535 ball.  60 G 3F hits ctr at 25 and 50 with 2 in. drop at 100, 80 G 3F shoots flat to 100..
fwiw...  :) Kerry 
« Last Edit: July 23, 2010, 03:50:26 AM by KNeilson »

Daryl

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Re: 100 yd deviation
« Reply #18 on: July 23, 2010, 04:35:45 PM »
Good post, Kerry-  I was dismayed at the amount SCL's gun was out- left at 25 and 50 but 6" right at 100. That seemed a bit much for 50 yards difference. Perhaps wind and sight picture helped to multiply the actual error.

Aligning the 'visible' rings is the main method of straightening barrels.  
« Last Edit: July 27, 2010, 03:48:52 PM by Daryl »

Offline KNeilson

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Re: 100 yd deviation
« Reply #19 on: July 27, 2010, 07:46:22 AM »
Thx Daryl, Although I was kinda questioning my sanity atm I was doing it, Ive been shooting several times since and I am very happy with the results. I actually placed in a local trailwalk this weekend!  For the first time I feel the rifle shoots where I point it. I can say also a clean bore with a very reflective surface is almost a must, Ive noticed it doesnt take too much to blur the reflections to the point they are hard to "read". ..  :) Kerry

Daryl

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Re: 100 yd deviation
« Reply #20 on: July 27, 2010, 03:54:15 PM »
Some few years ago, make that 1975, I drove to Kalispell to meet Les Bauska and John Buhmiller - alas, John had fallen down and was feeling poorly - I only spoke to him on the phone for a piece.  I did spend quite a bit of time - maybe 6 hours at Les's shop. We had a lot to go over as a buddy of his was then living near Smithers BC - hense my knowledge of John and Les at that time.
I ran a pile of ML barrels over his barrelstraightening machine - the one that looks like an octopus with short tenticals that held the barrel up towards a dusty, dirty window. The light coming through the window showed the rings in the barrel and I found it easy to straighten them using the 'machine'.  It was part of my early ML education. Returning home the next day, I had some 8 or 9 barrels for testing on my 1/2 stock- 'tester' as well as to supply Taylor with some barrels for his early work.  What fun!

Offline doulos

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Re: 100 yd deviation
« Reply #21 on: July 28, 2010, 01:06:44 AM »
Thx Daryl, Although I was kinda questioning my sanity atm I was doing it, Ive been shooting several times since and I am very happy with the results. I actually placed in a local trailwalk this weekend!  For the first time I feel the rifle shoots where I point it. I can say also a clean bore with a very reflective surface is almost a must, Ive noticed it doesnt take too much to blur the reflections to the point they are hard to "read". ..  :) Kerry
Your post reminds me of a show I saw some years back on the Outdoor channel about Savage arms. They had a fella who had been with them for many years checking their run of barrels the same way you describe. When the light showed "rings or shadows out of alignment the barrel was put on a straightening machine and bent in the direction the employee decided. I dont know if they still use this method but I was stunned that this was the method used for such accurate barrels.. And everyone I know who has a Savage rifle raves about the out of the box accuracy. They are shooters