45-70 accuracy problem, stock hole size?

[BulletBrain]

I have a 45-70 32" barrel that is giving me fits.  The frame came as a Buffalo Carbine 45 colt and it shoots real well in that caliber.  Most of the time around an inch and a half group for 3 shots at 100 yards.  I had the 45-70 added through the accessory barrel program and it gives me trouble.  It's zero will shift vertically and it groups inconsistently.  At first I thought the barrel was loose so I shimmed it with a few layers of foil.  With the stock bolt as tight as I dare turn it the stock will still move vertically back and forth.  It takes some effort and it don't move a lot maybe an eighth of an inch at the butt but I'm thinking the extra recoil of the 45-70 makes the stock move around giving me the inconsistent point of impact.  most of my problem is verticle.  I've thought it might be the forearm but it happens even when I rest it in the sand bags on the frame.  I guess it wouldnt hurt to take it off and try it but I'm wondering if any one recognizes these symptoms.

[keith44]

vertical stringing of the group is usually a loose stock, or poor or inconsistent lock up.

[cwlongshot]

I would pull the stock and see whats going on. Make it fit right!
 
CW

[Jimbo47]

Yep, If the stock moves at all you are wasting ammo!
 
It would be the same as you flinching!
 
If like you say the stock bolt is tight as you dare tighten it and it still moves, you need to add another washer or two on the stock bolt and try to tighten it again and that should cure the problem.
 
I had a similar problem with a Boyds thumbhole stock and I really had to put some mustard behind it.   Figured the worst I could do was shear off the bolt, strip the bolt hole or crack the stock!    Lucky for me none of that happened and it was tight from then on.
 
If placing an extra washer fails, you might call CS and tell them of the problem!

[cwlongshot]

No offence Jimbo, but Its a bolt, no need to call CS...   
Measure the depth of the threads in the receiver and be sure the bolt in not encroaching into the interior of the receiver... If it is, trim it off, either with a grinding wheel or a cut off wheel... Adding a washer or two is a good idea if you want to test fit. But more than a couple may cause loosening problems as you shoot.
Don't over think this, its simply a bolt attaching a piece of wood to a piece of metal.
 
CW

[Jimbo47]

No offense taken 
 
Just figured I throw out an idea on something that worked for me!....Fired a lot of rounds and no problems yet!   
 
Only reason I mentioned CS is because it's the safety net so to speak.

[ibgp3]

I think you missed a clue



"It came as a 45 colt and that barrel shoots well."

If the stock is tight when the 45 colt barrel is installed,
        the stock is not the problem.
If there is no play when the 45 LC barrel is installed
and there is play when the 45-70 barrel is installed,
the 45-70 barrel needs to be fitted.

[gcrank1]

As he says, it is the stock that is moving, not the barrel in the action.
I have wrapped HD tape around the shank of a stock bolt where it rides in the wood of the wrist; a real buttstock bolt, rather than common bolt, would have threads no larger than the shank dia. and the hole through the wood should be just over shank dia. The H&R hole is oversize, so all you are getting is a pinching action between the washer under the head and the treaded action, no support from the hole through wrist, thus play can be noticed. The tape wrap did tighten this up for me, and even though it was a quick fix for trials it is still there.
I have found that vertical stringing is often caused by inconsistent placement of the buttstock to the shoulder, especially with heavier kickers. This will be accentuated with a loose bolt hole to bolt fit. Competition rifles would never be made with that much tolerance and depend only on pinch pressure to hold in place, unless the fitting to the action had a mortice to lock the wood in place.

[BulletBrain]

Thank you all for your comments, especially gcrank1.  I think the problem is the "no support from the hole" theory.  But I will not know without further testing. Help me out, what is HD tape?  I've thought about wrapping the bolt in   paper to shim it so to say.  I've also thought about epoxying it in permanently but that seems drastic.  Other ideas are welcome.  I also thought about gluing a dowell in the hole and redrilling it smaller but that seemed sure to be a pain in the rear.  By the way the stock is a replacement more along the line of a plain wood pistol grip designed for a scope than the original walnut BC stock.

[gcrank1]

HD= heavy duty, in my case it was about 1" wide shipping tape with the translucent/cords running through it.
Your idea of the dowel and redrilling wont do much because of the stock bolt being a common bolt, just take a look at the thread and shank diameters on one in your bins or hardware store and you will see what I mean. The way they are made the thread dia. is larger in dia. than the shank. Maybe your bolt hole is even larger than the H&R though, but the tape idea might tell you if you are on the right track.

[BulletBrain]

I had some free time tonight and took the stock off.  There is plenty of room for tape and or paper on the stock bolt to tighten up the slop between the stock bolt and the hole.  I checked out the original BC stock and the bolt fit fairly tight in that stock.  In fact I have to tap it with a hammer to get it in.  I am a little nervous about recoil but I plan to get out and test the accuracy with the original BC stock on the weekend. I will let you folks know how it goes if/when I make it to the range.

[Goatwhiskers]

gcrank has the right idea on placement of the stock against the shoulder, it can have an effect.  I've specialized in single shots with two piece stocks and I can assure you that the fit of the bolt thru the hole has no effect.  Bed the stock to the frame same as you bed bolt actions with lite bolt tension, then torque the bolt after the bedding hardens.  You can add a washer if the wood inside has cratered a little, even bedding it in place if you desire.  If bedded correctly and torqued down the stock can't move, this is something usually overlooked in accurizing single shots and can be a major contributor to vertical stringing.  Here endeth the lesson.  Goatwhiskers the Elder

[BulletBrain]

Putting the original stock back on made a lot of differance.  Groups immediately tightened up.  I also noticed the shoulder position did make a difference.  By trying to get more consistent shoulder position, groups tightened up even more.  Last five shots went minute of angle at 100 yards. Both Factory FTX and Reduced reload FTX. Thanks everyone.  Oh and I replaced the iron butt with a kick eez magnum.

[cwlongshot]

Glad to hear you got the problems licked!!

I have long said CONSISTANCY is key to good shooting. Seems to be even more so from our beloved handis!!

CW

[OldBob]

   I think if I had that problem with a stock, I would find a piece of metal or hard plastic tube that gave a tight slip fit on the bolt . cut a section of it to length, ream out the stock to fit the tube, epoxy the tube to the stock..................... now you have a bolt hole that fits. Now bed the stock to the receiver and that problem should be gone.