Rifle shoots two groups

[ShaneG.]

If you recently bedded it I would look there for sure. I had one that drove me crazy for a while and turned out the recoil lug was bottoming out on the bedding. I removed material from underneath and the sides and the groups closed back up....this was also a Savage....and it didn't take much as I looked at it before by marking the lug with sharpie then installing it and the rub area was really small.

 

[Rem06]

I was shooting my 6.5x47 and noticed that I was getting two separate groups. Rifle seamed to switch from shooting in one group then the other randomly. Groups were 1.25 inch apart from center to center. The groups were arranged at a 45d angle to plumb.

At home I took my rifle apart and the only lose thing on it was my bubble level. Would that really cause that much spread? Picture of my bubble level.

seating depth,just went through this with my 22-250

 

[Liven The Dream]

Late to the list but ?
Is this a thing that happens when the barrel is clean , then shoots a second group ? Our changing Bullets or Powder without cleaning ?

 

[DOGCAPPER]

Had to rebuild the scope turrent on mine.

 

[Grimstod]

Late to the list but ?
Is this a thing that happens when the barrel is clean , then shoots a second group ? Our changing Bullets or Powder without cleaning ?

Same bullet and powder. And i do fowl the barrel first.

 

[Grimstod]

All are 5 shot groups at 100yards.
Left most one is 40.25gr and an OAL of 2.167
Middle 40gr at OAL 2.158
Right is 40gr at OAL of 2.168

 

[fredhorace77]

All are 5 shot groups at 100yards.
Left most one is 40.25gr and an OAL of 2.167
Middle 40gr at OAL 2.158
Right is 40gr at OAL of 2.168

Like mentioned, I would not forget to check this out with a different scope. Almost appears as if the reticle is shifting in the scope.

 

[Grimstod]

You stated it's a 6.5 x47 L? What kind of bullets are you using that gives a COAL only 3/8" longer than the case? what powder? How many rounds down the tube? Have you ever got some idea of it's accuracy baseline i.e. : multiple groups with a decent performing load (keeping the recipe exact) shot under the same ambient temp and conditions?

I am subtracting the 1in for the indicator bushing I use. Really readings are 3.xxxin etc

I know the term OAL gets abused a lot as many do not mention that they are measuring of the ogive or the tip.

 

[Forum Boss]

I've observed the same thing in a stock that flexed its foream. Simple test -- move the gun foreward on your front rest 8" (so it's no longer supported on the end of the forearms). Also:

1. Try with a different shooter
2. Try with a different scope

Do that before any expensive fixes.

 

[Toolbreaker]

I've observed the same thing in a stock that flexed its foream. Simple test -- move the gun foreward on your front rest 8" (so it's no longer supported on the end of the forearms). Also:

1. Try with a different shooter
2. Try with a different scope

Do that before any expensive fixes.

+1. 2 different guys behind the same rifle can rule out alot of variables.

 

[msinc]

Just curious if you ever resolved this issue positively????? Can you tell us the "smoking gun"??? I have a rifle doing the same thing, diagonal shift back and forth while shooting...to the same two points of impact. Mine is only about 1/2" to 3/4" shift at 100 yards. Just to be clear: shot 1 is dead on zero, shot 2 is 3/4" high right, shot 3 back to dead zero, shot 4 dead zero, shot 5 back up 3/4" high right. All bullets involved are touching another bullet, just in two groups. It bounces back and forth while shooting, it does not shoot a three shot group then something happens and it shoots another 2 shots together somewhere else.
In my case, it is not the scope. This scope was removed and verified on another rifle where it shot all 5 together.
Those that suggested "seating depth", could you elaborate please??? What about seating depth??? How exactly does seating depth cause this??? Not doubting any suggestions from any one, just would like to be clear. I have "tuned" many rifles and ammo, never had one do this as a result of various loads. These are all the same loads in my gun. Must be "teetering" on a fine line here....thanks in advance for any info.

 

[Grimstod]

Yes i did make big improvements. So the problem was bedding. I skim beeded the action and just about all the stess is gone. It does not shoft around now when i tighten the action screws.

Did a lot of shooting yesterday and not indication of double groups whatsoever. Seams to shoot a little better to.

New question. With a new bedding job i will need to redo load development?

 

[Auto-X Fil]

To add to the general discussion, many things can cause split groups, but the most likely candidate is bedding, followed by seating depth. Bipod issues will do this as well, if you're not shooting off bags.

msinc - take the gun apart, inspect the bedding, clean the action screws, and re-assemble with careful torque, being sure to seat the recoil lug into the stock with a firm bump before torquing. I bet that solves it. Is this a load that used to shoot well, or a new gun? If it used to shoot well, it's also possible the lands are eroding away and you need to seat a little further out.

A typical seating depth test for VLDs is here:
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

Grimstod - no, not unless you bedded the barrel itself forward of the recoil lug for a significant distance. Barrel harmonics, chamber dynamics, and seating depth won't have changed, and those are the three main parameters being optimized in load development.

 

[msinc]

Thanks for the replies fellas!!! It was not my intention to hi-jack this thread, I do apologize for that Mr. Grimstad, but since the problem described was exactly what my rifle is doing....I figured why make a new post??
Thanks a million for the link Auto-X Fil...Berger VLD Hunting bullets are exactly what I am shooting. This rifle is the second of 280 AI calibers I own. The first is a lightweight and this one is a little heavier for long range. I will give this test a try and report back. I previously seated touching the lands and proceeded to work on the powder type and charge. It seemed like I was always able to get results I needed this way and saw no need to deviate.
In regards to bedding, it seems today that many believe the recoil lug should not touch on the sides and bottom. If this is true, {and as many times as I hear or read it there must be something to it} how much clearance does it need and why??? Since I first started playing with rifles in the late 70's the general way to bed was mix up the compound, slop it in the stock and install the action. Next day pop it out, point it up, reassemble and go shooting...you wanted the action as tightly bedded to the stock as it could be. Now it sounds like add some thickness of tape to the bottom and sides of the recoil lug????
Just to be clear, because there was no mention of possible double groups in the Berger article...a shooter can have a given seat depth {wrong as it may be} cause double groups, and until the depth is changed/corrected the rifle, all other things being correct, will continue to shoot double groups because of where the bullet is located in the case {in relation to the chamber/lands}????