New Chassis- Groups opened up

[just jon]

Would appreciate insight.
Bought a Whiskey 3 Chassis, used but in good shape.
Put my Bergara HMR barreled action and i went from a sub moa (.5- .75). to over an MOA in the new chassis. Below is a pic of my best group from 100y.
I think i installed it correctly. Action doesn’t seem to wiggle or move.

Insight?

 

[B y r o n]

When you say you "think" you installed it correctly, how exactly did you install the action into the chassis?

 

[Milf Dots]

Someone with some wisdom will be along any second, but...

Are you shooting from a bipod, bag, or rest?

Did you use a torque wrench on the screws?

Because a chassis or stock is the interface between shooter and rifle- how do you feel about your position behind the rifle? Any chance your eye isn't in a good stable spot behind the eyepiece?

Of course it could also be the action to chassis interface...

 

[just jon]

When you say you "think" you installed it correctly, how exactly did you install the action into the chassis?

By the directions to torque specs.

 

[Sum Ting Wong]

Any rail attachment screws touching the barrel?

 

[just jon]

Someone with some wisdom will be along any second, but...

Are you shooting from a bipod, bag, or rest?

Did you use a torque wrench on the screws?

Because a chassis or stock is the interface between shooter and rifle- how do you feel about your position behind the rifle? Any chance your eye isn't in a good stable spot behind the eyepiece?

Of course it could also be the action to chassis interface...

Bipod. Rear bag. the same as with the stock that came with rifle (about 1500 rds). Consistently .5-.75 to what is seen in the pic with a chassis.

Eye relief was good

 

[Milf Dots]

Bipod. Rear bag. the same as with the stock that came with rifle (about 1500 rds). Consistently .5-.75 to what is seen in the pic with a chassis.

Eye relief was good

Sounds like you're getting a consistent cheekweld, so it does point to hardware and not software.

 

[Hawk in WY]

Magnum caliber? Recoil will exploit every weakness in form particularly with a new interface between you and the rifle.

Replace the bipod with a front bag.

 

[just jon]

Any rail attachment screws touching the barrel?

Don’t think. but will double check.

Magnum caliber? Recoil will exploit every weakness in form particularly with a new interface between you and the rifle.

Replace the bipod with a front bag.

No- 6.5 creedmoor.

 

[bbhank]

in my bravo chassis i found they all like to be a little tighter then they spec. play with the torque settings and see if it changes!

 

[st1650]

buddy of mine was chasing his tail for weeks on his 6 dasher on a Tikka action, turns out it was the MDT ACC chassis that was out of spec on the recoil lug. So it definitely happens even if it doesn’t wiggle.

 

[Trigger Monkey]

You're probably going to have to play with the torque settings as mentioned above to see what the rifle likes, KRG mentions this in their installation instructions, 65 in/lbs is a recommendation, not a rigid requirement.

Different action and chassis but when I had my Remington AAC-SD in an AICS it liked to be torqued down at 55 in/lbs, 65 in/lbs opened up the groups significantly.

 

[Ty21]

Try torquing the rear to 65 and the front to 60 seems

 

[supercorndogs]

Thats big group, something is very wrong or loose. I don't think tuning the torque should be he difference between half MOA and nearly 2 MOA. If it is, and thats common with this particular chassis, i would sell it and get something else.

Not sure if BErgerra is the same but sometimes you come across a hump backed or twisted remington action that doesn't play nice with a v block style chassis. Its usually characterized by the rear tang lifting away from the chassis and as the front action screw is tightened, then you can see and feel the rear action screw pulling the rear tang down as its tightened. Usually when this is the problem you see a rifle shooting tiny groups at few different places. I.E a 9 shot group might end up looking like 3, 3 shot groups 1.5 MOA apart. The way your group looks makes me think something is loose or the scope crapped out.

 

[Holliday]

Would appreciate insight.
Bought a Whiskey 3 Chassis, used but in good shape.
Put my Bergara HMR barreled action and i went from a sub moa (.5- .75). to over an MOA in the new chassis. Below is a pic of my best group from 100y.
I think i installed it correctly. Action doesn’t seem to wiggle or move.

Insight?

The first thing I would check is to make sure the lug is not bottoming out prematurely (preferably not at all) and that it is sliding back solid against the back of the lug.

 

[Secant]

Did previous owner bed any portion to their action?

When checking for barrel contact, also look to see if bolt handle is in contact with chassis and/or front action screw is anywhere close to contacting bolt. Also make sure recoils lug is in full contact prior to full torque of action screws.

 

[just jon]

Did previous owner bed any portion to their action?

When checking for barrel contact, also look to see if bolt handle is in contact with chassis and/or front action screw is anywhere close to contacting bolt. Also make sure recoils lug is in full contact prior to full torque of action screws.

 

[just jon]

I did check for this and the action moves slowly. Although there is a washer witht front action screw. When i removed it the bolt would move forward but would not lock. Put the washer back and all worked. Action screw still too close?

 

[just jon]

Secant- that should say moves smoothly in the first sentence

 

[Secant]

I did check for this and the action moves slowly. Although there is a washer witht front action screw. When i removed it the bolt would move forward but would not lock. Put the washer back and all worked. Action screw still too close?

Just from your description, that sounds too close for my preference, and I'd probably trim that screw a little bit.

 

[Ty21]

The screw doesn’t need to be trimmed that’s why the washer is in the front action screw to make the correct spacing so your bolt will close if you take the washer out your bolt won’t close. Like you explained in your testing.

 

[Secant]

Washers should be used for wider bearing surfaces to better distribute loads, not as spacers. You'd just use a shorter screw (or trim the one you have) if you needed a shorter screw.

If there's no contact between the action screw and bolt, it doesn't need trimmed. You can have a circumstance where your bolt closes but slightly contacts the front action screw - not saying that is your actual problem. Obviously I haven't seen your setup and I can't tell you if the screw is contacting in any way. But based on the description, spending 30 seconds to slightly trim the screw doesn't hurt anything and could be part of the problem (unless you rule it out). Same concept if your bolt handle is contacting the chassis or polymer skins - if there's contact, relieve the chassis or skins.

 

[Ledzep]

Put a small ring of JB weld or Devcon around the action screw holes in the chassis and SNUG the action screws until it cures. Release coat the action & screws. DO NOT torque the screws until after it's cured.

That will remove much of the torque sensitivity.

 

[just jon]

Thank you everyone for you time. so far i have..
Trimmed the front action screw
torqued the action screws from 65 to 55

4 shots, three at .72 with one flyer. Much better. But i am consistently getting one flyer. But that is not odd for my Bergara although it is happening more consistently. Will keep working those toques and seeing what the system likes

I am saving up for a better action and barrel. at this point this barrel and action will have to do.

Again, thank you and any more wisdom is welcome.