Bedding A Chassis

[Devildog]

Curious how many are bedding there chassis? Yes I know you shouldn’t need to.

The reason I’m asking is because I recently put together a 300 PRC and I’m using a popular brand chassis on here, I’m having problems with the front action screw, it keeps coming loose. Before someone ask yes I’m following the manufactures torque specs and torque sequence using my fix it stixs.

I’ve had to retighten it after just about every trip out. I’ve probably run about 120 round threw the tube. I’m going to call the manufacturer and ask for some assistance. I normally shoot Foundation or Manners stocks but I thought I’d try something different, I like the chassis but I need a fix. Any options?

 

[sgtsmmiii]

Small amount of blue Loctite on the threads?

 

[Devildog]

I thought about that but I’ve read a lot of post out there that say don’t do it, just looking for options. Thanks for the input.

 

[FCrifles]

Blue loctite wont hurt anything. Or Nord-Lock washers, like MPA uses.

 

[Hoyt7mm]

Maybe try adding a lock nut of some sort? I've not experienced that particular issue before.

I've bedded chassis in the past. In one instance (good chassis & custom action in 300wm) it did improve accuracy.
I'm bored this off season with alot of marintex laying around so I've slowly been bedding all my chassis rifles. No issues with any of them beforehand, but my OCD will be appeased for a little while.

 

[Devildog]

Thanks for the replies I am using the Nord-lock washers. I emailed the company today, the rep is out till next week. I may just go ahead and bed the chassis. I did a search and found another hider having had the same problem with a chassis from the same company, I guess they bedded his action an it resolved the problem. Of course this is partly why I bought the chassis so I wouldn’t have to bed it, in the end it’s probably the best fix at this point. Time to read up on bedding actions!

 

[1moaoff]

Nord lock washers!

 

[CK1.0]

I would check with the chassis maker to be sure you’re using the correct action screws for your chassis/action, if you’re using the lock washers it should stay put.

IMO the chassis is supposed to be configurable where you can change things out, bedding it kind of defeats this purpose.

 

[Devildog]

Nord lock washers!

I’m using them!

 

[Devildog]

I would check with the chassis maker to be sure you’re using the correct action screws for your chassis/action, if you’re using the lock washers it should stay put.

IMO the chassis is supposed to be configurable where you can change things out, bedding it kind of defeats this purpose.

I’m using the nord-washers and action screws provided by the manufacturer. I agree you shouldn’t have to bed a chassis.

 

[1moaoff]

Ok well that is different. Not trying to be silly but I have a few questions
Are washers stacked correctly? After assemy do you hear a pop at the range when they have loosened? Any lubricant on the bolts? Chassis manufacturer? Is recoil lug against machined area or is there slop/gap?

Pictures?

 

[CK1.0]

I wonder if you have to just use a stronger torque setting or maybe check your fix it stix against a fat wrench or other in/lb wrench to know it's legit..? Or, it might just be that the torque spec that works in a Foundation/Manners is different than what works in the chassis, you might be able to try going to what's max for your action (if it's rated for more than you've tried so far).

 

[Devildog]

I can’t tell you if the washers are stacked correctly, they were already installed on the action screws when I received the chassis, after tightening the action screws the first time I checked them by backing them off and I did get a loud pop.

If I recall it was recommended to put a small amount of oil on the action screw, so yes I applied a drop,on the front and rear screws. Mind you the rear action screw stays put and has never loosened. I need to check for a gap, or slop in the front lug.

I have to get some pics to post. It’s a Matrix chassis. (I’m not bashing anyone here, just trying to fix a problem)

 

[Devildog]

I wonder if you have to just use a stronger torque setting or maybe check your fix it stix against a fat wrench or other in/lb wrench to know it's legit..? Or, it might just be that the torque spec that works in a Foundation/Manners is different than what works in the chassis, you might be able to try going to what's max for your action (if it's rated for more than you've tried so far).

I have a fat wrench I can check it, I’d have to call deviance to see what the max action screw torque is. I certainly don’t want to jack up my action. Thanks for all the ideas I’ll check it out

 

[CK1.0]

I have a fat wrench I can check it, I’d have to call deviance to see what the max action screw torque is. I certainly don’t want to jack up my action. Thanks for all the ideas I’ll check it out

The Matrix looks like a pretty bad-ass chassis, I'd be surprised if you had to bed it, but it's relatively new too so maybe the suggested torque spec isn't perfectly dialed yet for your particular setup...

 

[Devildog]

The Matrix looks like a pretty bad-ass chassis, I'd be surprised if you had to bed it, but it's relatively new too so maybe the suggested torque spec isn't perfectly dialed yet for your particular setup...

I really like it, I’m sure there’s a simple fix for this problem. I’d just like to understand why it’s happening so I can feel confident in the fix. Globing a bunch of blue loctite as has suggested doesn’t feel right to me.

 

[max1840]

I can’t tell you if the washers are stacked correctly, they were already installed on the action screws when I received the chassis, after tightening the action screws the first time I checked them by backing them off and I did get a loud pop.

If I recall it was recommended to put a small amount of oil on the action screw, so yes I applied a drop,on the front and rear screws. Mind you the rear action screw stays put and has never loosened. I need to check for a gap, or slop in the front lug.

I have to get some pics to post. It’s a Matrix chassis. (I’m not bashing anyone here, just trying to fix a problem)

I have a matrix also and on my third trip to the range my action screws were loosening ( 90 rounds fired to this point). I degreased them and re-torqued to spec and all has been well so far. This happened about 2 months ago and I've not had it happen again. I've put 175 rounds through it since. 300PRC

 

[Devildog]

I have a matrix also and on my third trip to the range my action screws were loosening ( 90 rounds fired to this point). I degreased them and re-torqued to spec and all has been well so far. This happened about 2 months ago and I've not had it happen again. I've put 175 rounds through it since. 300PRC

Good deal, I’ll have time over the holiday to tear it all down and check everything and put it back together. I know the instructions say to check the torque at 100 rounds and then every 500 as part of normal maintenance. Mines been coming loose after every 25-35 rounds. Ill get it whipped!

 

[Heffo]

Thanks for the replies I am using the Nord-lock washers. I emailed the company today, the rep is out till next week. I may just go ahead and bed the chassis. I did a search and found another hider having had the same problem with a chassis from the same company, I guess they bedded his action an it resolved the problem. Of course this is partly why I bought the chassis so I wouldn’t have to bed it, in the end it’s probably the best fix at this point. Time to read up on bedding actions!

Hi mate I have a couple Ultimatum actions....one I had a manners made to suit which is brilliant, and the other that was a pain in the bum. Long story short the third stock/chassis combo was in an MDT ACC. Tightening the action screws over 30inlbs would bind the action locking the bolt. Anyway bedded the ACC and the problem is completely solved. Cheers.

 

[Dthomas3523]

How much torque are you applying?

Degrease the screws and the threads in the action. Torque to 65 in/lbs. If it’s still coming loose, try another action. If that one doesn’t come loose, then you can start comparing the action bodies where they contact the chassis and see if you can remedy it via bedding.

 

[montana3gunner]

I bed most of my chassis, even though they usually don't NEED it. I've had XLRs, MPAs, and now MDTs. All were good chassis, although I'm really happy with the MDT ACC and XRS. I've seen plenty of guys win matches with non-bedded chassis ....and yet I know many top shooters who bed all their chassis.

Bedding just makes me feel better and it does help to decrease the likelihood of problems. If your action screws are loosening, chances are that it's because your action is moving around inside that chassis, and bedding should help that.

Keep in mind, those of us shooting PRS/NRL with bedded chassis are shooting little 6mm/6.5mm cartridges. Big difference between those and your 300 PRC. Much higher forces going on with the PRC. The lighter the chassis and the bigger the caliber, the more I want a bedded chassis. I definitely like to bed the lightweight chassis I use for hunting and Long Range hunting matches like the Hornady Match.

Obviously, by bedding, you'll lose the option to swap other actions in and out of that chassis, which is a big plus for some. Almost all of my actions are Curtis Vectors and most of those are so close in dimension that I can swap them around in the bedded chassis as needed. I do usually keep one chassis non-bedded in case I run into a situation where I need to run a random barreled action.

Use the same techniques for bedding a chassis as any other stock, just be mindful that depending on how much bedding is used it's going to raise your action by that amount - so you may have to adjust your mag height and/or tune your feed lips.

Also, some day if you want to sell that chassis - it's sometimes harder to sell it when it's been bedded.

Good luck - Hope you get it worked out!

 

[Devildog]

@montana3gunner thanks for the reply, I’m 99% sure I’m going to bed the action and be done with it. Never bedded one myself but I’m sure I can figure it out. I’ve spent enough money on this build and with the goal of shooting extended ELR I’ll do whatever it takes to make this a successful build.

Early on in my build I’d spoke with John Kyle of Foundation Stocks he had hoped to have a stock I could use for my build but no luck yet. I ran out of patience waiting so I went down the chassis road, I didn’t expect any issues but I guess sh!t happens. Im going to take the whole thing apart this weekend and get fixin. Thanks again to everyone for the replies.

 

[montana3gunner]

Tons of great videos online about bedding. I'm thinking of doing a video on some tips on chassis bedding specifically - a combo of things I've come up with and tips I've gotten from friends in the Industry. If I do, I'll try to remember to post a link here.

Good luck and it's only bedding - you can always re-do it.

 

[Animal357]

Sound like the threads on the action are out of spec

 

[MDT_Josh]

Just wanna throw my 2 cents in here; heavy recoiling rifles (like the 300 PRC) in ANY chassis or stock that is starting to be weighted up more (like the MPA Matrix) is like an unstoppable force meeting an immovable object and something is bound to give. Not to mention that the action screws on the R700 and clone actions have very limited engagement based on the internal geometry!

What I have been recommending (and doing myself) is installing all of my actions screws on heavier chassis with a small amount of Loctite 242 (Blue) or Loctite 290 (Green) and torquing actions screws above 60-65 in/lbs. The thread locker helps with the backing out and doesn't seep into the action causing clearance issues. It also gives you that extra peace of mind and you won't be in the middle of a match worrying if your action screws are gonna break free on you. Additionally, we have found that certain actions and v-block cutter profiles are more susceptible to backing off action screws than others.

Hope this helps,
Josh

 

[Dthomas3523]

Just wanna throw my 2 cents in here; heavy recoiling rifles (like the 300 PRC) in ANY chassis or stock that is starting to be weighted up more (like the MPA Matrix) is like an unstoppable force meeting an immovable object and something is bound to give. Not to mention that the action screws on the R700 and clone actions have very limited engagement based on the internal geometry!

What I have been recommending (and doing myself) is installing all of my actions screws on heavier chassis with a small amount of Loctite 242 (Blue) or Loctite 290 (Green) and torquing actions screws above 60-65 in/lbs. The thread locker helps with the backing out and doesn't seep into the action causing clearance issues. It also gives you that extra peace of mind and you won't be in the middle of a match worrying if your action screws are gonna break free on you. Additionally, we have found that certain actions and v-block cutter profiles are more susceptible to backing off action screws than others.

Hope this helps,
Josh

I’d also imagine making sure the recoil lug is making as much contact as possible (and bedding the lug if necessary) would help tremendously with heavy recoil + heavy stock.

 

[Threadcutter308]

Sound like the threads on the chassis are out of spec

Threads are in the action and on the mounting screws/bolts. I've never seen a chassis or modern day stock that had threads in it. Perhaps others have and I just don't get out of my cave much.......

 

[MDT_Josh]

I’d also imagine making sure the recoil lug is making as much contact as possible (and bedding the lug if necessary) would help tremendously with heavy recoil + heavy stock.

Yeah, full contact on the lug shouldn't be an issue though in most chassis, but if there is uneven contact or something was machined right then for sure, bedding it will solve a lot of issues! Heavy recoiling rifles (much like rimfires) have a great way of exposing stuff like this that light recoiling, 25 lb 6/6.5mm's just skip over haha.

Josh

 

[Dthomas3523]

What I’m getting at, if the recoil lug is making proper contact, there shouldn’t be much recoil energy exerted on the action screws.

 

[MDT_Josh]

I hear what you're saying, but you're always going to get flex in the system as nothing is perfectly rigid, however, integral recoil lugs are preferred for a reason. Additionally, there is a lot of vibration caused by the shot sequence and aluminum has a harder time damping it than say fiberglass or micarta.

Josh

 

[Dthomas3523]

@308pirate

I need an engineer as I’m at the end of my knowledge here and this is an interesting topic.

 

[Animal357]

Threads are in the action and on the mounting screws/bolts. I've never seen a chassis or modern day stock that had threads in it. Perhaps others have and I just don't get out of my cave much.......

My bad, I mean threads on the action. Might be too loose?

 

[Threadcutter308]

My bad, I mean threads on the action. Might be too loose?

Could be, I've never seen that though. But, anything's possible. It's a good idea to be on the lookout for it.
I'm in the "clean the action threads and bolt threads, blue Loctite them (if you feel that's necessary) and torque to 65 in/lbs" camp.

 

[THEIS]

Hi,

Sorry if it is listed, I have looked but could have overlooked it...

What receiver are we talking about?

Recoil lug supplied by receiver manufacturer?
a. Have swapped recoil lug and get same results?

Action screws supplied by receiver manufacturer?
a. Have swapped set of action screws and get same results?
b. Are action screws made by receiver manufacturer?

Have you put dye on the recoil lug and fired the rifle then look at see if there were any high spot smears?

What do the action screws feel like when screwing them in with receiver not in the chassis?

Shooting chassis on way more recoiling systems than a baby 300PRC for decades and never had it happen.

Sincerely,
Theis

 

[308pirate]

Sound like the threads on the action are out of spec

LOL there's a million fucking reasons why a joint would loosen up with threads that are just fine to a go/no gage

 

[1moaoff]

Oil on the bolts may be the culprit. Lubricated fasteners have different torque spec

 

[BLopina]

It is the oil on the washers / bolts. Degrease and it won’t happen. Had the same issue. Know this is an old thread but it might help others