Bullet Impact Change???

[JON8777]

I when I switch between barrels I am noticing an impact change. The group is either directly high or low (by an inch or three).

What do I need to change to fix this?

My forend is the PH with heavy barrels, Leo rings and bases with Nikon scopes.

[Lone Star]

Clarification please - when you remove and re-install the same barrel, its POI changes vertically?  What are the group sizes you are using to determine the changes in POI?




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[GameHauler]

I got the impression to a different barrel (caliber)
so I left this one alone

[JON8777]

When I swap from the 25-06, put a different barrel on, put the 25-06 back on (week or two later) the POI changes.

This is also happening with my 223

[Lone Star]

I can think of several possibilities but this is very rare IME. 

1)  The locking bolts are not seating consistantly.  Clean them and the barrel cutouts thoroughly with spray cleaner then try them dry, without oil.  If no better, add a few drops of quality oil.

2)  If you are using different amounts of torque on the forend bolt/s this could be a cause.  If the forend hangers don't fit the forend well differing amounts of pressure could stress the barrel up or down.



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[Hopalong7]

    I'm betting on the forend mounting screw torque(no large bets, but that's where I'd look first).  I do not use a torque wrench but just snug the screws lightly with only my finger tips on the driver.  I do a LOT of switching around but seldom have a bullet impact problem.
GOOD SHOOTIN', Walt 

[gunrac]

    I'm betting on the forend mounting screw torque(no large bets, but that's where I'd look first).  I do not use a torque wrench but just snug the screws lightly with only my finger tips on the driver.  I do a LOT of switching around but seldom have a bullet impact problem.
GOOD SHOOTIN', Walt 

I'm kinda leanin toward the forearm also. Before I floated the forearms on my different barrel's, mine were never REAL consistant as they are now.. It definitly made a big difference for me. I still have to make sure they centered and seated with equilvent torque. I also don't use a torque wrench.

[JON8777]

When I mount the forend its with light pressure, just enought to snug the screws with two fingers on the screwdriver shaft.

The gun will shoot 1/2 groups, its just moves the POI when the brls are swapped.

Anyone use a Locker pin?

[expeditionx]

When I mount the forend its with light pressure, just enought to snug the screws with two fingers on the screwdriver shaft.

The gun will shoot 1/2 groups, its just moves the POI when the brls are swapped.

Anyone use a Locker pin?

The hinge pin might shift enough to make a difference, but that can happen even when you simply open the action.
 A locker pin prevents this from happening.  The forearm bolt tightness or looseness will affect the barrel harmonics
and can likely cause a shift in poi. The same occurs in boltguns and lever actions. Try this yourself.
The next time your out shooting your gun. Start with the forearm barely tightened then shoot a group.
Tighten the bolts more then shoot another group. Repeat the process. A barrel vibrates similar to a tuning fork
and pressure changes affect how the bullet reacts with the barrel.  This is why barrel tuners
are a factor in the shooting sports.

http://www.eabco.com/HicksAccurizer1.html
http://www.varmintal.com/atune.htm
http://www.henrich3.com/biathalon_stabilizer.htm

Hanger bar systems can avoid significant pressure changes against the barrel
and this can prevent poi changes when switching barrels with the same forearm.

[JON8777]

I am thinking about purchasing a walnut stock set from GunStocks and putting a pillar bedding to it.

Whats a good sell price for a used black buttstock, PH balck forend, regular forend and a 209x50 forend set?

[gunrac]

Good deal. Glad to hear that. I despise plastic's! or the so called composit's. Guess it's part of being old school.

[JON8777]

I have been kicking the wood stock set for a good 10 years on this gun.

The first used rifle barrel came with a Syn forend. So after buying the brl and scope, a $40 syn stock was more apealing than a $150 wood stock set.