In regards to my new Bergara B-14, Did I really screw myself up that bad.

[Frgood]

Okay, this is a confessional post, and I know I've done some stupid - So don't rub it in too much.

I've had my Tikka T3 for about a year and am insanely happy with it. So, of course, I decide to get a second LR rifle for tinkering. [facepalm]

I bought a Bergara B14 because of reputation and it conformance to R700 action. without even firing it, I got an MPA Hybrid chassis.

During first firings, after sight in and chassis adjustment, I'm finding the groups to be significantly off. The scope is a Zeiss Conquest v4, which will be the subject of a different thread. But suffice to say the scope is more than adequate for 100 yd break in.

My question is - Where to from here?
Do I consider barrel break and fire a couple hundred rounds while watching the progress?
Do I mount it back in the original stock and retry?

As I mentioned in another thread. I used (6.5 crd) Berger 140 and got the huge MOA. When I used Prime 130's I got perfect vertical strings consistently.
Based on those results. Maybe I'm on the right track and should not over think this. Just stick with the 130's and focus on my read bag technique.

Thoughts?

 

[Jabot]

What do u mean groups r off . Bigger ,off center. Did u fire it out of original stock, then out of chassis?

 

[Frgood]

heh heh - I really hoped someone would not ask that question.
The groups, estimated, are in the 1.5 - 2.0 range. with the 140's. The vertical stringing with the 130's was 2 inches which indicates to me that that is completely on me.
I'm having a bitch of a time with my rear bag, But that is all whole different conversation, at the moment. I can work on that one.

 

[Frgood]

What MOA with each?

How was the chassis installed? Ideally, you push the action and recoil lug back until it stops and torque it in. Otherwise the rifle can walk a bit in the chassis until it finds the stopping point.

The chassis lays in quite nicely but there is a spacer in the front lug that adjusts as you torque the action into place. The instructions, and MPA's install video, make note of a moment during the install and prior to final torquing, of a 'snapping' feeling when laying it in. I did not get any change in sensation during the tightening process, but did check the lugs fitting as I was bolting the changer in to place.

Their is a slight slope in the chassis's lug slot so that as you tight down the action it will lock into place. But, to your point, I cannot be sure as I have no prior experience.

 

[Frgood]

What do u mean groups r off . Bigger ,off center. Did u fire it out of original stock, then out of chassis?

Hence my feeling of extreme stupidity. No I did not fire out of the original stock. I don't think a 'D'OH' is sufficient for that feeling.

 

[jphil108]

Can you move the muzzle relative to the chassis? The video they have on their LugLock says that there are two different inserts for the different recoil lug thicknesses. One is for the standard R700 lug at 0.250” and the other is for the 0.350” switchlug that WTO designed. I suspect the Bergara uses a .250” thick lug like the Remington standard so you would need to use the larger diameter lock piece or the lock feature won’t work.Once you know that the lug lock is correct, make sure it’s loose before you drop in the action or it may not allow the action to drop in all the way. I’m not sure about their install process but I would pull your action loose and start over. to me it makes sense to loosen the lug lock enough that it will wiggle back and forth, drop your action in and make sure it’s sitting right in the chassis, Use one hand to push the action toward the butt pad and hold it tight against the chassis as you tighten the lug locK and make sure that it doesn’t try to push the action up out of the chassis. MPA state 30 in-lb for the lug lock, don’t exceed that.Once you have the Lug lock tightened down, put in your two action screws and tighten them down to bergaras specification ( I don’t know what it is and I don’t want to provide a number to screw you up, they should list it some where or you can call them). I don’t know your level of technical expertise so I will just say to use an appropriate in-lb torque wrench for install meaning no offense if you already know this. That procedure should ensure that the action is full seated in the chassis and pushed up hard against the recoil lug so there should be no rearward movement of the action relative to the stock under recoil.

What kind of scope rings and bases are you using? Is the base tight to the rifle, are the rings oriented properly and tight to the base, are the rings the right sized for the scope, and are the rings tight to the scope? Again, all of these things should be done with a torque wrench. If you’re using a Rail be sure that you push your rings forward ( toward the muzzle) snuggly as you tighten the rings, that ensures that the scope rings don’t have a gap with the slot in the rail. The video below may help some;



MPA and Bergara both have solid products so my gues is either their is some weird incompatibility between them or the install didn’t go quite right.

 

[Frgood]

Can you move the muzzle relative to the chassis? The video they have on their LugLock says that there are two different inserts for the different recoil lug thicknesses. One is for the standard R700 lug at 0.250” and the other is for the 0.350” switchlug that WTO designed. I suspect the Bergara uses a .250” thick lug like the Remington standard so you would need to use the larger diameter lock piece or the lock feature won’t work.Once you know that the lug lock is correct, make sure it’s loose before you drop in the action or it may not allow the action to drop in all the way. I’m not sure about their install process but I would pull your action loose and start over. to me it makes sense to loosen the lug lock enough that it will wiggle back and forth, drop your action in and make sure it’s sitting right in the chassis, Use one hand to push the action toward the butt pad and hold it tight against the chassis as you tighten the lug locK and make sure that it doesn’t try to push the action up out of the chassis. MPA state 30 in-lb for the lug lock, don’t exceed that.Once you have the Lug lock tightened down, put in your two action screws and tighten them down to bergaras specification ( I don’t know what it is and I don’t want to provide a number to screw you up, they should list it some where or you can call them). I don’t know your level of technical expertise so I will just say to use an appropriate in-lb torque wrench for install meaning no offense if you already know this. That procedure should ensure that the action is full seated in the chassis and pushed up hard against the recoil lug so there should be no rearward movement of the action relative to the stock under recoil.

What kind of scope rings and bases are you using? Is the base tight to the rifle, are the rings oriented properly and tight to the base, are the rings the right sized for the scope, and are the rings tight to the scope? Again, all of these things should be done with a torque wrench. If you’re using a Rail be sure that you push your rings forward ( toward the muzzle) snuggly as you tighten the rings, that ensures that the scope rings don’t have a gap with the slot in the rail. The video below may help some;



MPA and Bergara both have solid products so my gues is either their is some weird incompatibility between them or the install didn’t go quite right.

Spot on. I will re-seat the action as it doesn't hurt to double and triple check and will report back.

The scope setup I'm pretty confident with but am going to reset the rail and rings as I need to clean the screws after yesterday's rain.
[printing this thread to have bench side as I recheck the work] Hopefully, I can retest this upcoming weekend.

 

[jphil108]

You might also give MPA a call and see if they have heard of any issues with mounting a Bergara action before. I have a fairly basic tool bag that I put in whatever car I’m driving and so far it has prevented three disappointing days at the range. It has also gotten me home from some bad vehicle problems in the middle of nowhere, but that is a topic for a different thread.

 

[Frgood]

jphil108, I just went online and found that the installation instructions have been updated since my initial install instructions.

I just finished re-seating the action and barrel and it seem to have been smoother than prior memory. although, not sure if that is different practice or just the additional experience. I found the action to be level with the built-in level and the scope rails ell into place as well. The install goes easier when you really understand the spacer and install scree order. everything fell right into place and was no struggle. With the mindset of confidence, it all feels quite secure without any stressing.


I say this all now, Well see as soon as I get back to the range.

 

[jphil108]

Range time reality is always the true measure of a correction. Does it look like it’s sitting different in the chassis?

 

[Frgood]

Range time reality is always the true measure of a correction. Does it look like it’s sitting different in the chassis?

Visibly no. But one thing I noticed is that the chamber, scope rails, and the chassis bubble levels all align properly. Previously, there was some tweaking to get the chamber level with the chassis bubble level. This time, it all seem to fit in nice, square, and upon completion perfectly aligned. Hopefully, in the previous install I tweaked and fiddled with the levels too much causing misalignment and improper torquing.

 

[jcmullis2]

I remember something about mpa action screws having a problem of loosening up even after being torqued to the recommended 65inch Lbs.

 

[Frgood]

I remember something about mpa action screws having a problem of loosening up even after being torqued to the recommended 65inch Lbs.

I think this is the thread but that sounds like a fairly unique situation. Also, the shooter notices that the action is very loose after 20-30 rounds. This sounds like something that would be a very noticeable issue.

MPA action screws loosening ...

Just curious if I'm alone on this issue ... where the two screws on my MPA-300-WMBA rifle that connect chassis to action, keep loosening after 20-30-ish rounds. Worked with MPA and got their "lock-washer" solution, and also followed their advice to over-torque to 65 or even 70 in/lbs ... but...

www.snipershide.com

 

[ThePretzel]

I use the MPA locking screws, which are the ones that give the "snap" feeling you might have seen in an installation video (when you loosen the screw after the first torquing you want to feel a "snap", because that means it locked in correctly). Those can prevent the action screws from loosening up, but so can a simple lock washer if you're concerned about it.

Getting the wedge LugLock system correct is a big deal though, and it definitely needs to be done AFTER you have installed and torqued the main action screws. If you tighten the LugLock before the action screws, even just a little, it will prevent the action from seating properly in the chassis and you'd probably see issues with the action sitting level or not. Once the LugLock is tight though, that action isn't moving anywhere. Before I knew about that system I tried removing an action from an MPA chassis and couldn't figure out why it wasn't coming out no matter what, even though both action screws were sitting in my hand. It was stuck as tight as if the action screws were still in there, so it definitely does a good job of holding everything in place.

 

[jphil108]

I use the MPA locking screws, which are the ones that give the "snap" feeling you might have seen in an installation video (when you loosen the screw after the first torquing you want to feel a "snap", because that means it locked in correctly). Those can prevent the action screws from loosening up, but so can a simple lock washer if you're concerned about it.

Getting the wedge LugLock system correct is a big deal though, and it definitely needs to be done AFTER you have installed and torqued the main action screws. If you tighten the LugLock before the action screws, even just a little, it will prevent the action from seating properly in the chassis and you'd probably see issues with the action sitting level or not. Once the LugLock is tight though, that action isn't moving anywhere. Before I knew about that system I tried removing an action from an MPA chassis and couldn't figure out why it wasn't coming out no matter what, even though both action screws were sitting in my hand. It was stuck as tight as if the action screws were still in there, so it definitely does a good job of holding everything in place.

I stand corrected on the order of assembly, definitely follow what the manufacturer says to do. It seems like the goal in either method is to keep the recoil lug in contact with the mating surface on the chassis while the action screws are tightened down to avoid any binding between lug lock and screws that may relax under recoil.

 

[KYAggie]

If would suggest taking tools and the factory stock to the range next time you go and if it’s still a 2 moa shooter, put it back in the factory stock and see what you get.

 

[ThePretzel]

I stand corrected on the order of assembly, definitely follow what the manufacturer says to do. It seems like the goal in either method is to keep the recoil lug in contact with the mating surface on the chassis while the action screws are tightened down to avoid any binding between lug lock and screws that may relax under recoil.

LugLock after action installation just means you don't accidentally get the LugLock nut underneath the lug and then your lug is sitting on top of a round surface. Wouldn't surprise me if that was the issue you saw, because if you tighten the LugLock first without the action fully pressed down into the chassis (by the action screws, for example), it can slip off the recoil lug and settle underneath it instead.

A trick for ensuring the recoil lug is in contact with the chassis mating surface during install is described in the MPA chassis install guide HERE. Basically just get the action screws started, then flip the chassis upright so it's sitting on the buttstock with the barrel pointed up. Then you can snug up and torque your action screws. This makes sure that the recoil lug is always pressed against the mating surface of the chassis for the entire process, and then tightening down the LugLock makes sure that the recoil lug never shifts or bounces away from that mating surface under recoil.

 

[Frgood]

I stand corrected on the order of assembly, definitely follow what the manufacturer says to do. It seems like the goal in either method is to keep the recoil lug in contact with the mating surface on the chassis while the action screws are tightened down to avoid any binding between lug lock and screws that may relax under recoil.

Just got back from the range and there is a remarkable difference.
Reinstalling did the trick. In regards to the lug, in this case, get the lug seated square and complete first. with no other consideration. Then, with the butt on the bench, so the barrel points up and the lug seats completely rearward, you can get the front (upper) bolt started, begin to torque down the lug spacer, and start the rear bolt. Torque the front to 25 ft/lbs. then the rear. At this point I used a level to check the chamber against the bubble level on the stock.
When all is good final torque to 60 ft/lbs.
I believe this is the new instructions except for the level check.

Today, each round went exactly where I aimed. Most of the time I watched the hole appear exactly where I placed my crosshairs at 100yds.

So to groups. Well now , I have absolutely witnessed every one of my mistakes. off the bench, I was less than .75. It is quite disheartening to see your body positioning and trigger pull go phooey in real time.
When I went prone, my preferred position, I saw everything I need to work on. But again, every bullet landed exactly where I aimed., no matter how messed up that was. On average, I was 1 MOA, but that variance is 100% me. So I'm feeling quite confident in the rifle.

Thanks you all for the input. it is all excellent expert advice that produces the exact result desired.

I can say what I think about the MPA chassis, but It comes from not enough wisdom to be of value. Coming from a world of wood stocks and slings, this type of rifle is something that will require modification of positioning. I find the rifle very light; almost too light. I also have a year old Tikka T3 A1 which weighs a bit more. As a result it is a very stable platform to shoot from. I'm reaching out to 950 from my first attempt.

With both rifles, and not using a sling, I see the choice of rear bag and should placement to be the key. The Atlas bipods are rock solid and no issue there.

Since my clavicle is misshapen from an old injury, it can be tricky to get the correct position. I borrowed an Armageddon rear bag (Squishy Bag?) at the range and that particular size and fill seemed steadier than the small handheld read bag I have. A lot less movement.

 

[spife7980]

With both rifles, and not using a sling, I see the choice of rear bag and should placement to be the key. The Atlas bipods are rock solid and no issue there.

Since my clavicle is misshapen from an old injury, it can be tricky to get the correct position. I borrowed an Armageddon rear bag (Squishy Bag?) at the range and that particular size and fill seemed steadier than the small handheld read bag I have. A lot less movement.

I would look into a pint size game changer with the sand fill. Its heavy for its size... as its a sack of sand... but its solid yet malleable. I was hesitant to use it as a rear bag for a couple of months when I first got it but since Ive started using it I havent used any of my old bags with the little plastic beads that seem to give way so much easier. Now I use it for most everything I do.

 

[Frgood]

I would look into a pint size game changer with the sand fill. Its heavy for its size... as its a sack of sand... but its solid yet malleable. I was hesitant to use it as a rear bag for a couple of months when I first got it but since Ive started using it I havent used any of my old bags with the little plastic beads that seem to give way so much easier. Now I use it for most everything I do.

Thanks I will take a look

 

[Frgood]

Follow-up:
After reseating the chassis and re-installing the scope, with a slow double checking of everything, I was able to go out today and try toe zero at 100 and practice confirming trajectories out to 296 yds. Tomorrow hopefully I can run it out to 900.

A funny thing happened on the way to 300 (Zero Mostel reference is deliberate). I had run out of the nice Prime 6.5Crd 130 ammo and figured I'll use S& B 130. I saw not expecting much from that ammo as it has been spotty in the past. Once zero, I shot the following whole collecting chrono data.

To say the least, I was pleasantly surprised and very happy. The calc to 296 yds was spot on and one shot confirmed it with aplomb. From talking to a local ballistics guy, we were able to show that the Magneto-speed chrono accounts for the shift in POI.

Thanks to the advice from you guys. It was spot on and, as a result, I am looking forward to trying out our new LR range at VGHC.

 

[JaoeyP]

Looks like it's doing better! My HMR really shined after 150-200 rounds down the tube. May get better still.

 

[TheBoctor]

I find that usually stringing issues can be chalked up to a bedding issue. Glad you got it sorted out.

 

[Mk32784]

If you’re having rear bag problems I love my precision underground bags.

 

[Slab74]

I remember something about mpa action screws having a problem of loosening up even after being torqued to the recommended 65inch Lbs.

This is why I always mark my action screws once I have them torqued properly. One quick look and I can tell if they have moved.

 

[iukamedic]

The hmr I had shot those Berger 130’s the best.

 

[Macman25]

Here is a thread with several options for marking screws.

Gunsmithing - What type of marker/paint pen do you use to mark/reference the position of screws and maybe highlight a front sight?

In the course i took the instructor advocated marking the closed position of torqued screws or bolt heads so that one might easily ascertain whether the screw/bolt had loosened. I'm not sure what type of pen or marker would work for this application. One in which it would have to adhere to...

www.snipershide.com

 

[TC_Override]

Follow-up:
After reseating the chassis and re-installing the scope, with a slow double checking of everything, I was able to go out today and try toe zero at 100 and practice confirming trajectories out to 296 yds. Tomorrow hopefully I can run it out to 900.

A funny thing happened on the way to 300 (Zero Mostel reference is deliberate). I had run out of the nice Prime 6.5Crd 130 ammo and figured I'll use S& B 130. I saw not expecting much from that ammo as it has been spotty in the past. Once zero, I shot the following whole collecting chrono data.
View attachment 7360032


To say the least, I was pleasantly surprised and very happy. The calc to 296 yds was spot on and one shot confirmed it with aplomb. From talking to a local ballistics guy, we were able to show that the Magneto-speed chrono accounts for the shift in POI.

Thanks to the advice from you guys. It was spot on and, as a result, I am looking forward to trying out our new LR range at VGHC.

View attachment 7360032

Thanks for posting this question and all the advice from the forum. I've learned a lot. Glad you got this resolved.