Ya think it's the scope?

[revbc]

Have a friend of mine's 45/70 I load for that is stringing a 3 shot group about 4-5" at 100yds.  The load is a previously known decent load.  39.2 grs of imr4198 behind a 300 gr Hornady JHP.  It was doing worse the other day, brought it home, did a trigger job, sanded the forearm and floated it with orings.  This first pic is how it shot today.

The only factor that has changed (It did shoot this load fairly well at one point) is a new Nikon Omega 1.5x5 scope mounted in burris signature steel rings.  Everything seems tight.  Even put a mirror on the end of the scope, the crosshairs seem to track ok.

What do ya think?  Anyone got a better load for the 300gr Hornady with imr 4198? 

I think the shooter was ok, bottom is a  pic of two shots from my Ultra 45/70 after I finished shooting his.

[handi243]

i sanded mine when it was shooting bad then put a small piece of rubber at the top of the forearm close to the muzzle snugged the screw just a little. went from shooting 2-3" to under a inch. give it a try good luck.

[revbc]

Thanks Handi

Already done all of that.

[parson48]

The only way to eliminate the scope as the culprit is to try another one, preferably one known to be good.

Doesn't sound like you're shooting enough for barrel temp to be an issue.

For me, vertical stringing has typically been because of either a hot barrel or pressure on the barrel.

Perhaps a dirty barrel?

[Jimbo47]

I'm shooting a 350 grain Hornady jacketed softpoint bullet using 31.7 grains of IMR4198 and getting 1" at 100 yards with three shot groups.
 
I'm using an "O" ring under the forearm and a 3x9 Bushnell Banner scope.
 
By the looks of your target I think I would suspect the scope as long as you have a good tight lockup, and there is no play between the receiver and barrel, and the fact that you already worked the forearm, and it previously shot that load well, so that only leaves the scope, or the mountings as the likely culprit.
 
 

[yukondog]

I would think the scope/set up, have you tried shooting it without the forend on?

[gcrank1]

Remove the scope and rail, make sure the rail screws arent bottoming out into the holes (I do it one at a time, tighten down and try to wiggle the rail), then torque them in.
IMHO, it is unlikely the load as it is only vert. stringing, not random impacts enlarging the group.
Also back off the stock thru-bolt a tad and wiggle the contact end of the wood to metal fit. If it wiggles a bunch you might want to try what I did on one, that was doing the same as this rifle, tape the bolt shank to increase dia. where it runs through the wrist. Lately Ive been using HVAC 'foil tape', at about .005 thick, for a number of 'shimming projects and like it a LOT. It is expensive for a roll, maybe ask your furnace man if he can spare you a 'foot or two'; it goes a long way.
Anyway, get the play out of it at the wrist and make sure there is no oil on that contact face to the wood (you could even coat that smooth surface with varnish to give it some 'bite', and torque it all up. If the wood has compressed with recoil/use you might even want to put another washer under the thru-bolt head.
Worked for me  .

[Monteria]

It seems to me that a bad scope would be all over the place rather than stringing. If you do determine that it is the scope though, I would like to hear about it. I have 4 of the 1.65-5x Omega, including one on my shorty 45/70, now.

Steve

[tacklebury]

Has there been a change in the weather since last test?  4198 is a bit temperature sensitive and as the barrel heats it could be pre-heating the shell as loaded and causing each shot to raise drop depending on temperature.  Not sure if the temperature is cold where you are, but might play into it. 

[JB White]

Revbc,
 
Did I read your notes in the pic correctly? It appears your one-holer was with a different load than was used in his?
 
 

[bikerbeans]

revbc,
I have had this type of "group" with a couple of different Handis and it has either been an issue with the load and real bad velocity spread or something loose in the gun.  Improving my reloading techniques solved the velocity issue.  The culprit with the Handi one time was a tiny bit of slop in the stock as gcrank1 mentioned earlier.  Another time was just a very small amount of play in the pivot that slightly varied how the gun locked up each time.  If it was a scope problem your up and down group would probably be a "buckshot" type pattern.   A hot barrel can also do the veritical stringing number but you are not exactly hot rodding that 300 grain bullet so I don't think that it your problem.
Good luck.
BB

[revbc]

Thanks for all the advice.  Going to look into some of it more, but first off I'm going to swap the scope and mount setup.  The load shot had previously shot well, and had shot well in my 45/70. 

The second pic is a different load, just shot it to make sure it wasn't the shooter.

[JB White]

Thanks for all the advice.  Going to look into some of it more, but first off I'm going to swap the scope and mount setup.  The load shot had previously shot well, and had shot well in my 45/70. 

The second pic is a different load, just shot it to make sure it wasn't the shooter.

I was curious if you may have tried swapping loads between the two rifles just to check differences, or a repeat in stringing with a different load. Since it's on the bench already then go ahead with what you're doing now. Are there still loads remaining from that batch? Those are the ones I would start with before trying anything else.