Point of impact change

[aulrich]

I was doing some "field position" practice off my shooting sticks I was shooting at dessert sized paper plates 5", simulating a coyote sized kill zone, I learned a couple of things

1. 300m is a long way off , when you shooting in the sitting position off of sticks 200m is much easier.

2. I think I have a major point of impact change (or a bad pull)the reason is that my 200m group was about 5" right of center but still a good group considering shooting conditions. Now I did not have my regular shooting rest along  but I am reasonably sure that the gun was properly sighted in (one thing to double check next time out). Actually I had noticed that on my coyote kills last year  the hits seem to be farther right than what I had expected. Then I had attributed it to the vaugaries of shooting called coyotes.

So for back ground my formal shooting rest I usually support off the hindge ping, but the sticks seem more confortable 2.5-3" on the wood. My sticks are just homemade using 1x1 ala Varmint Als bi-fur pod.

So lets assume I do have a significant point of impact change and not I had a bad day, I need more practice (can always use more of that the 300 m targets proved that) or I have a bad pull, what are my options.

Ideally I would like to have minimum POI change, given none is likely not realisitc with a break open.

Obviously the simplest option is to alter the sticks so they feel better while supporting at the hinge pin. and if shooting unsupported making sure to support there

But mechanically with the gun, what should I be looking at.

The gun had a reasonably tight lock-up but I will give it the feeler guage check to confirm it is still OK.

I have done nothing to the forend, the gun came out of the box shooting good groups (and that has not really changed) so I did not mess with it. It can be described as tight on the barrel.

I have to confirm this bit but the forearm spacer does not show even wear. if memory serves the right side shows less wear.

[Fred M]

aulrich.
A little theory.
A right hand twist will move the bullet to the right at long range it has to do with the coriolis force effect. the more twist the more the bullet will move to the right in the northern hemisphere and to the left in the southern.

If you want shoot a lot at 3-400 yrds you should sight in 1 to 1.5" to the left at 100yrds. When shooting for score in a match from  100 -300 yards you need to make a correction of about three clicks to the left (9/8") on a target scope at 300.

If your barrel vibrates and bouces off the left side of the forarm you will shoot to the right at long range. You have to make up your mind to either full bed or free float anything else will not be satifactory.

On a Handi I like the forearm under tension and become an integral part of the barrel with all connecting joints tight. I have proved this system to my own satisfaction.

This system does not penalize you if your stick support is off the fore arm. I never shoot off the hinge pin.

[nomosendero]

A 5" POI shift to the right AT 200 YARDS is far too much to be the result of a right hand twist.

[Mac11700]

A 5" POI shift to the right AT 200 YARDS is far too much to be the result of a right hand twist.

Ain't that the truth

Actually I had noticed that on my coyote kills last year  the hits seem to be farther right than what I had expected.

Did you try a rock solid rest at 100 yards to check you scopes zero before proceeding to 300 yards???.....If not...I would suggest this...it might comfirm what you already know...

Mac

[Fred M]

nomosendero .
Of course 5" is a big drift at 2 or 300 yrds  but it can easy be of multibles.
I only pointed out two causes. When shooting off sticks canting can make you shoot way off, and so is paralax. In a Handi the torque in the loose action will add to it.
 
An error like that has to be addressed from all sorts of angles. It takes practically nothing to be off 5" at 300 yards, even with a 1 moa rifle. What about wind drift a new game for most people. Do you know how much a light varmint bullet drifts in even a light breeze of 10mph?

I think I am wasting my breath, maybe someone has better ideas.

[nomosendero]

Multiplicities of variables yes, but the twist is hardly an issue at 200 yards, a whole bunch of things would matter more.
I have been shooting my AR alot lately & I am looking here at some groups shot at 300 yards in allmost no wind. The drift to the right may be 1/4", & that is 300 yards, not 200. I see that all of the time but out at 600 yards & beyond it doesn't hurt to factor in twist. 

Do I know about wind & Varmit bullets. Yep, I also have some targets here shot by the AR in some wind. Yea, it matters alot to the left or right of course dependeing on wind direction.

Good Evening Sir

[cwlongshot]

I have not herd this right hand twist theory before...I also don't generally shoot past 300yrds. I have not seen it in my rifles, but as they say you learn something new everyday...As the yardage increases it may take a greater effect.

 I would also recommend you check your scope. Be conscious of the wind.

Shooting at these longer ranges require more delicacy setting up your rifle as there are WAY more variables to take into consideration.
The first one that came to mind was the way you scope is mounted. Is it straight? I mean are the cross hairs canted at all. I do not mean are they straight for you I mean are they square to the bore of the rifle. If no, make it square, re-sight in.

You do not mention caliber, if so I missed it. Lighter bullets are going to have a greater shift as the wind takes it effect on them. In a light caliber with a light bullet a good steady wind could easily shift your group inches to one direction. Just because its not blowing where you are on the bench doesn't mean squat 100, 200, 300 or even 50 yards away. You generally do not notice wind deflection at 100 but its definitely something to consider if you shoot light for caliber bullets at long ranges.

 CW

[aulrich]

Fred

Your forend bedding method was the first thing that cam to mind  so it's on the this along with the rtv bedding method.

The scope can be an issue it is an Chinese OEM but it's been good far.

It was breesy and that could be it, next time out I will have both sticks and the cradle. So even if it is breezy i'll have both to compare.

Scope cant is a strong possibility both in setup and shooting technique I will start there especially since my shooting partner thinks all of my scopes are slightly canted. Any useful gadget I could/should get ?

And for the record it is a 204 ruger that has given me sub moa off of the cradle since I have bought it.

[Fred M]

aulrich.
quote
Scope cant is a strong possibility both in setup and shooting technique I will start there especially since my shooting partner thinks all of my scopes are slightly canted.

Yes that is a good point to start and you should start from scratch.

Some things you should relize the more of the windage/elevation adjustments you use the further you get away from the optical center of the scope. When this happenes you get into the aria of spherical aberations not a good place to be. 

A set of Burris rings with the ecentric inserts will let you line up your scope without using much of the adjustments. Many bases are badly aligned with the bore

Of course you should start with the x-hair in the optical center. Bore sighting and rotating the excentric bushings until the bore and the barrel point in the same place. A collimeter is what I use, works really well for this purpose since I can do it on the bench.

To set up a scope the action should be level or plumb in case of a handi and held in place in that position. Find a spot where you can hang up a rock with a 1/4" rope.
With the action level rotate the scope until the vertical x-hair lines up with the the rope and tighten the rings in that position.

You can install a little flip up scope level for your long range shots these little jewels work realy for well about 30 bucks. Great when shooting off sticks. I had one for years should get another one for my 6x47.

I never said that the 5" drift was caused by the coriolis force only that it contributes to drift. Canting is a lot greater factor.

Maybe this sound like a lot rigamarol, but there are no shortcuts to long range accuracy.

[aulrich]

I googled collimeter but I could not get a clear picture of what it is, my guess is that it is one of those optical bore sighter devices. Years ago I used one as a gun shop employee it was the bushnell with the aubor. I  like that one the best I am not sure I trust those magnetic ones.

And some bad news I did a quick feeler guage check and as it turns out it has loosen up some, I can close on a .004" feeler guage. Probably should get that down PDQ.

[Fred M]

aulrich.
Yes it is an optical bore sighter with some solid and some adjustable spuds. Every now and then I need a size I don't have like the 375 Win  so I make one on the lathe. I don't believe I have one for the 20cal nor the 17.

I am all gung ho about a 1885 Win Low wall in 17 HMR rim fire. Although I wont buy it unless I can find the proper scope bases. One thing for sure this action wont shoot loose.

Well with a Handi there is never a dull moment. Shooting loose seams like standard practice. Fill it in with Devcon Steel it lasts for quite a while and it is easy to redo when it compresses. My last fix was good for 250-300 rounds in the 6x47 it had good 5 thou gap. It is shooting again like it supposed to.

[safetysheriff]

hold the rifle with you hand on the barrel out front of the forearm, and use you hand/fingers to insulate the rifle from your shooting stick(s) or support.    the further the fulcrum from your  shoulder that the rifle pivots around, the less impact will that pivoting/flinching/wobble have effect on the bullets path.   your shoulder may move laterally maybe 1/4" to 1/2", for example, while the muzzle will change its position / point of aim only negligibly.

it's like the outer edge of the minute hand on a clock moving in a large circle, while its 'inner' edge circumscribes a much smaller cirlce or circumference.    an inch of movement on the outer edge circumscribes less degrees of rotation than does an inch of movement on the 'inner' edge.

take care,

ss'   

[Woodchuck Sniper]

I shoot off the same style sticks very much.

I don't have the smith skills that some have on this thread but I will add one simple tip that worked on my handi and maybe others can comment as to why it worked so well.

I added a piece of foam weather strip (pressure/harmonics bed) to the forearm tip.
A) Using two "O rings" as listed above on the lug.  I took common foam weather strip 3/8" wide x 3/16" thick x roll found at home stores with the sticky back.  After coating the inside of my forearm with tung oil to seal out moisture which BTW needed no sanding,no high spots etc.  Along with the two O rings, about 1/2" back from the end of the forearm I add the foam strip.  Cut approx. 3/4" long and placed across the barrel channel to just slightly come up the sides about 1/3.  This combined with my action screw being tight plus 1/4 turn and then marked (torque amount??) gave upward pressure and acts as a vibration isolator.  The amount of upward pressure was not measured and is likely less than some recommend but it is definately there to a degree with the two O rings in place. I added two O rings because of the foam strip height.  The foam strip compresses to maybe 1/16"-1/8" depending on torque.

I have tested my POI many times and it is spot on (home property rifle range), this was my biggest concern as a varmint hunter.  For my gun (Handi 22 Hornet), my 5 shot groups at 100 yards shrunk with the above and proper torque.  From my varmint al type shooting sticks, I can flip the sling over the stick and shoot with the gun resting in the Y near the end of the forearm which as you noted is much more comfortable and accurate, with out a poi change.  I have tested it.

This foam strip pressure bed is a common sporter rifle accuracy trick to try.  I have tried this on other sporter bolt action rifles and did not get the same results as with the Handi.  In some previous cases it brought groups in some but, poi changed with humidity etc.  Not the case with the Handi  ,  the Handi responded and held POI remarkably well. The Handi was also much more seletive to action screw torque than any other rifle I have owned.  IMO- it all adds up to why this simple 15 minute accurizing trick worked well on the Handi. I beieve this to be "harmonics and vibrations"issues mostly with the slight upward pressure being second, the two O rings along with the foam tip pad give it a simple two contact point vibration/float/isolation for lack of better terms.  This is simple to add or remove and weather proof.  IMO- it is simular to Fred's foam bed concept listed above in mechanics.

A simple tip to try,
Bill / W.S.

[Fred M]

Bill.
You are on the right track. Cut down on vibrations anywhere and you will improve accuracy. If you read my accurizing a Handy in FAQ you will find that this write up deals mostly with killing vibrations or at least reducing them. Besides it is not all that hard to do.

[aulrich]

Ran into an odd thing, so experiment with the gap a little I tried the shim method so since the gap is somewhere .003" and .004" I figure the .002" shim that I had would work just fine. But when I put it in the action does not close. Now when I first got this gun I did have the open on fire bug.  10 minutes with a hard stone as per the FAQ and it closes up. 

So if I want to close the gap up does it make sense to shim and stone the shelf?

Now maybe I just need to use a .001 or .0015 shim (and when I find it I will try)?

I double check the forend spacer and that is OK it looks like it's giving even pressure.

I should be heading to a buddies next weekend for a little archery elk I should have time middays (the elk bed in a no-hunting provincial park) to to some testing. First off I will just confirm my suspicions before going on to forend bedding. But I have an idea for the sticks, I am going round the corners over (at least on the rest portion maybe the whole thing) with a router then pad it somehow,my first thought is a few layers of hockey sitck tape or a thin layer of foam then covered with tape.

[Fred M]

Aulrich.
You forgetting when you add a 2 thou shim, you reduceing the sides of the 1/2round seat by 4 thou. So your hinge pin wont seat all thge way down.  The upper part of the shim should be feathered out to nothing.

Best yet your shim only needs to come up 45 deg on both sides of  from dead center bottom, the shim should not be wider than 0.294" or 1/4 radius. then the hinge pin wont be restricted on the sides.

I like the Devcon Steel putty a lot better. for the above problem.

[aulrich]

Just thought I would update the situation it seems the problem is either not there or not nearly to the same extent. I did some testing over the weekend. I shot off my rest and sicks both resting on and off of the forend, it was not the best group I had ever shot by a long shot but the poi's between the different positions were OK, though I will be doing a forend bedding job to see if I can get it better.

My guess is that it was a combination of my trigger pull ( I was pretty aggressive with the trigger that day) and my inability to read the wind right, was causing most of the problem

[Mac11700]

My guess is that it was a combination of my trigger pull ( I was pretty aggressive with the trigger that day) and my inability to read the wind right, was causing most of the problem

As usually the case and very easy to do... ...Glad you got a handle on the problem...now you can go enjoy it...

Mac