The "a chassis should not need to be bedded" myth........

[Rio Precision Gunworks]

The topic comes up ever so many months and you'll find quite a lot of people will chime in with the blind "you shouldn't have to bed a chassis" line. The recent "what the pros use" chassis article from Precision Rifle Blog revealed some numbers I think many will find surprising. Before getting into the article, let's get one point out of the way:

For that to be a universal truth (chassis should not require bedding), it would mean that any chassis that requires bedding to remove something like a zero shift.......is by default a defective chassis. But, you'll find that most of the time when a chassis requires bedding that it is easily within manufacturing specs and all but identical to a chassis of the same brand that doesn't require bedding. So, you can't have it both ways. Either chassis are subject to bedding when needed, or chassis requiring bedding must be defective.

Here is a screenshot from the article pertaining to MPA. There were 50 shooters in the top 200 using an MPA chassis of some sort. Just shy of 50% of those 50 shooters have their chassis bedded. Everyone in the top 20 with an MPA chassis reported their chassis to be bedded.


The TLDR version: it's impossible for universal fit bedding areas will match up to every action enough that bedding will never be required by a properly machined chassis.

It's perfectly fine not to bed a chassis. However, I'd encourage anyone who insists you shouldn't have to bed a chassis to take some time and either rationally reevaluate your opinion, or do some impact testing on various chassis (you'll find that many will experience some zero shift of some sort).

 

[Rio Precision Gunworks]

Conversely, almost no one in the top 200 beds their Foundation Stock. This will negate the "people are just being abundantly cautious when bedding their chassis."


As if that were the case, you would see this reflected in Foundation Stocks......as the different opinions and mindsets are fairly similar on things like this. So, you should see a higher amount of Foundation users taking the cautious route if that were the case.

In fact, I would say this is likely indicative that a Foundation almost never requires bedding but some people are being cautions, but some chassis do require bedding as a commonality and not an outlier.

 

[TheOE800]

I bet I could get my ACC Elite bedded and show an improvement in consistency. Between the two I have (with identical CNC actions) there’s a difference in engagement based on wear mark patterns I observed when I had them apart recently.

 

[st1650]

I bed my foundation stock but only because there was no Nuke inlet back in the days and I had a really good deal on a used 737r genesis 2.
Shoots lights out, my most accurate barreled actions sit in that stock

 

[Stavey]

If the utmost precision is the goal. No matter wether a chassis or a stock. You should bed the action. Here’s a screenshot from the Borden website. I also talked to Jim before having my Mountaineer action bedded into a Matrix pro chassis.

 

[Rio Precision Gunworks]

If the utmost precision is the goal. No matter wether a chassis or a stock. You should bed the action. Here’s a screenshot from the Borden website. I also talked to Jim before having my Mountaineer action bedded into a Matrix pro chassis.
View attachment 8380387

Jim also still cuts scope rings down and beds them as well. I almost never bring that up here as it would really get people up in arms.

 

[TheOE800]

Jim also still cuts scope rings down and beds them as well. I almost never bring that up here as it would really get people up in arms.

I’m starting to believe in stuff like that after taking delivery of my TacOps. I’ll still buy cnc machined scope rings without dicking with them though.

 

[Rio Precision Gunworks]

I’m starting to believe in stuff like that after taking delivery of my TacOps. I’ll still buy cnc machined scope rings without dicking with them though.

Agreed. I'd say the scope thing is a bit more on the min/max side of things, where the chassis bedding is closer to the necessity side at times.

 

[kthomas]

I have to admit, that neither of my two JAE's are bedded.

I do wonder what gains, if any, would be achieved in my specific case in bedding my JAE's. Precision is really good, especially with my 6BRA, and I have no problem removing the barreled action and re-installing with little to no shift. The downside to bedding a chassis is that you effectively permanently alter that chassis, and render it useful for only one specific action.

I also wonder if some chassis' more than others benefit from bedding. Not all chassis' are designed the same, and even consistency across the interface between the chassis' and action probably changes to varying degrees across brands. What brands benefit the most from bedding, and which ones the least?

 

[Tokay444]

I had to bed the rear tang on my JAE to get stress free action contact. That’s transferred quite well through multiple actions.

 

[kthomas]

I had to bed the rear tang on my JAE to get stress free action contact. That’s transferred quite well through multiple actions.

What downrange performance change did you see after performing that rear tang bedding?

 

[Tokay444]

Went from a sometimes one hole gun to a consistent one hole gun.

 

[stanley_white]

When this subject comes up I always wonder about the amount of contact or lack thereof between the action and chassis being a determinent i.e. a square action like a Howa or an AI vs a tubular action like the Remington 700 and its clones.

-Stan

 

[ma smith]

A technical issue with bedding in a metal chassis, in part, I thought was lack of depth of the bedding material. Is this not a real problem, and if its being overcome, what are the best practices (eg prep) of how to actually bed the chassis?

 

[ARShooter91]

Is the precision needed to be at the top of PRS even a scale to judge the extent on how effective the improvements of bedding are?

 

[Rio Precision Gunworks]

A technical issue with bedding in a metal chassis, in part, I thought was lack of depth of the bedding material. Is this not a real problem, and if its being overcome, what are the best practices (eg prep) of how to actually bed the chassis?

Most are bedding the front and rear of the chassis. Sometimes milling out pockets for the bedding. It’s not the same, but when bedding a foundation you will mill it out.

Obviously it’s chassis dependent.

 

[Rio Precision Gunworks]

Is the precision needed to be at the top of PRS even a scale to judge the extent on how effective the improvements of bedding are?

It is if you have a zero shift. Bedding isn’t just for a single purpose.

 

[jbuck88]

My take on it is the chassis is machined to give a square perpendicular flat for the lug to mate with and provide a means of centering the action in the chassis, V-blocks or whatever. Bedding probably helps dampen the harmonics and provide rotational stability in the assembly process.

So I'm not sold on the PRS guys do it so we all need to follow suite. They are probably just trying to eliminate any variables they can. Whether real or potential.

 

[kthomas]

So I'm not sold on the PRS guys do it so we all need to follow suite. They are probably just trying to eliminate any variables they can. Whether real or potential.

I think this can be said about most things PRS (and other shooting disciplines).

It is however an interesting discussion, and I would be interested in hearing from more people about what specific chassis' they have bedded, and what the benefits they saw (or didn't see), were.

 

[Rio Precision Gunworks]

My take on it is the chassis is machined to give a square perpendicular flat for the lug to mate with and provide a means of centering the action in the chassis, V-blocks or whatever. Bedding probably helps dampen the harmonics and provide rotational stability in the assembly process.

So I'm not sold on the PRS guys do it so we all need to follow suite. They are probably just trying to eliminate any variables they can. Whether real or potential.

As mentioned in the second post, it’s unlikely it’s just a better safe than sorry reason. If so, it would be reflected in other chassis/stocks.

It’s not very likely that people using Foundation stocks are less cautious than those using MPA.

Most that bed chassis have done some sort of testing and have seen things like a zero shift from rough handling of the rifle.

The point of referencing the people in the article doing so isn’t the driving reason to do it. It’s just an example of how common it is, compared to how uncommon most expect it to be.

People have been bedding chassis for years. It’s similar to dialing wind. 3-5 years ago, you’d get crucified for telling the internet you dial wind, however many top shooters were dialing.

 

[jbuck88]

I think this can be said about most things PRS (and other shooting disciplines).

It is however an interesting discussion, and I would be interested in hearing from more people about what specific chassis' they have bedded, and what the benefits they saw (or didn't see), were.

I think that would be a interesting discussion for sure. I'd like to heard about before and after performance from first hand experience.

 

[Rio Precision Gunworks]

I think this can be said about most things PRS (and other shooting disciplines).

It is however an interesting discussion, and I would be interested in hearing from more people about what specific chassis' they have bedded, and what the benefits they saw (or didn't see), were.

Most I know including myself will take a rubber mallet or dead blow hammer or even the palm of your hand. Slap the rifle around. Hit the barrel, etc.

If zero shifts, bed the chassis. If not, up to you. Some will just default to bedding out of caution, but that caution is warranted via knowing that it does happen from time to time.

 

[jbuck88]

As mentioned in the second post, it’s unlikely it’s just a better safe than sorry reason. If so, it would be reflected in other chassis/stocks.

It’s not very likely that people using Foundation stocks are less cautious than those using MPA.

Most that bed chassis have done some sort of testing and have seen things like a zero shift from rough handling of the rifle.

The point of referencing the people in the article doing so isn’t the driving reason to do it. It’s just an example of how common it is, compared to how uncommon most expect it to be.

People have been bedding chassis for years. It’s similar to dialing wind. 3-5 years ago, you’d get crucified for telling the internet you dial wind, however many top shooters were dialing.

In my limited experience I think harmonics plays a part, and I'm sure bedding a chassis will help deaden it, if that is the right word. Also I would guess it has to help with zero shift, but it would be great to see some hard data.

 

[ARShooter91]

It is if you have a zero shift. Bedding isn’t just for a single purpose.

Yeah I think my question still applies. I've never seen any crazy shift shooting from 0-90degrees, certainly less than half moa at 100m. With good components I'd think that's the norm as it has been with me even with cheap Bravo's.

I can see bedding a laminate/wood stock having a much more noticeable impact.

 

[diggler1833]

I got into this when everyone was getting either a McMillan and bedding it, or an H-S Precision and was skim bedding it.

It is a habit of mine to bed everything...with the lone exception being my AT-X. That rifle is extremely accurate, and I have not observed a cold bore shift with my 6GT barrel (jury is still out on my 6CM barrel). Maybe bedding isn't necessary all the time?

What I do know is that a properly heat-treated and stress-relieved barrel that is properly bedded into a stock has always provided me with zero cold bore shift. That alone is enough to make me do it every time, because a lot of my shots are at living things.

 

[Rio Precision Gunworks]

In my limited experience I think harmonics plays a part, and I'm sure bedding a chassis will help deaden it, if that is the right word. Also I would guess it has to help with zero shift, but it would be great to see some hard data.

Data is going the be almost 100% anecdotal. Such as “I had a zero shift.”

I’ll look for the podcast. Phil Cashin publicly states he purposely uses round body actions (as opposed to something like a lone peak) in V block chassis as it’s less common to need bedding. But that they see plenty of their chassis the require or improve via bedding.

 

[Rio Precision Gunworks]

Yeah I think my question still applies. I've never seen any crazy shift shooting from 0-90degrees, certainly less than half moa at 100m. With good components I'd think that's the norm as it has been with me even with cheap Bravo's.

I can see bedding a laminate/wood stock having a much more noticeable impact.

If you’ve never experienced a zero shift that will cause you to drop enough points to matter at a PRS match, you’re either very fortunate or haven’t shot enough to encounter an issue.

It’s pretty common to see the muzzle end or middle of a barrel get whacked up against a steel prop pretty hard. Sometimes multiple times if someone is having a bad day.

 

[pnorris]

Is it really a zero shift? The optic is mounted to the action, right? Bedding doesn’t change that correct? Instead, I look at it that you’re more comfortable as the action is not perhaps moving around at all. It’s certainly not a zero shift though.

 

[Tokay444]

In my limited experience I think harmonics plays a part, and I'm sure bedding a chassis will help deaden it, if that is the right word. Also I would guess it has to help with zero shift, but it would be great to see some hard data.

Harmonics doesn’t play a part.

 

[Tokay444]

Line contact is better than point contact, and full contact is better than line contact. It’s all about stability.

 

[ShtrRdy]

I read that article and was wondering if the 'large' number of MPA chassis being bedded was primarily due to the early MPA action screws loosening up? I'm a fairly recent MPA chassis owner/user and haven't had any trouble with the action screws loosening. The current production of MPA chassis uses a self locking type of action screw which may take care of the problem.

Nord-Lock Washers

Wedge-locking security for bolted joints subjected to extreme vibration and dynamic loads

www.nord-lock.com

 

[iceng]

Chassis can benefit from bedding. This isnt some weird space magic.

The action inlet on many chassis is "generic" and not specifically cut for brand X, the way foundation or others are.

Chassis have minimum compression on torque of action, composite stocks do have a tiny bit of compression. When you torque in a receiver to a composite stock, it squishes into place nicely. A chassis is "you get what you get".

Machining a chassis you have a tolerance. Be it +/-0.1mm or +0.03/-0.00mm, you have to have an acceptable limit. The machined receiver has the same. When you start stacking tolerances, you potentially get issues. Its why some people never have an issue, and some do.

Sincerely,
Someone who makes chassis.

 

[ma smith]

But I was told 100% of "competition" chassis come factory ready for competition...

 

[iceng]

They are ready for competition out of the box. Are you ?

Perhaps tell Satterlee he needs to bed his rifle to win.

 

[ma smith]

They are ready for competition out of the box. Are you ?

Perhaps tell Satterlee he needs to bed his rifle to win.

Don't take it personally, LOL

 

[Baron23]

Most that bed chassis have done some sort of testing and have seen things like a zero shift from rough handling

Citation please. I didn’t see any imperial evidence of such reported in that article. I think you may be going beyond the available evidence.

 

[ma smith]

My questions were more about how to bed a chassis,
and the technical answer is...you re-manufacture the chassis...

ie, blow out the "precision" machining, to create space,
the introduce the plastic interface (marine tex, etc)

which raises the point of why not just sell them
this way...ie for real competition shooters...

it would be cheaper and save a couple steps.

 

[Tokay444]

Citation please. I didn’t see any imperial evidence of such reported in that article. I think you may be going beyond the available evidence.

I had to bed the rear tang on my JAE-700 to get it where I wanted it.

 

[Tokay444]

My questions were more about how to bed a chassis,
and the technical answer is...you re-manufacture the chassis...

ie, blow out the "precision" machining, to create space,
the introduce the plastic interface (marine tex, etc)

which raises the point of why not just sell them
this way...ie for real competition shooters...

it would be cheaper and save a couple steps.

I think you’ll find most smiths just skim bed aluminum V-block chassis. There’s plenty of space already there for the plastic to fill, unlike a 1 for 1 Foundation inlet.

 

[ARShooter91]

If you’ve never experienced a zero shift that will cause you to drop enough points to matter at a PRS match, you’re either very fortunate or haven’t shot enough to encounter an issue.

It’s pretty common to see the muzzle end or middle of a barrel get whacked up against a steel prop pretty hard. Sometimes multiple times if someone is having a bad day.

Probably a little of both. Im not much into precision run n gun to the extent I'm banging into things. Yes occasionally I'll smack the muzzle against sumthing especially if suppressed.

 

[rustyinbend]

I have three MPA chassis bolt-action rifles. 22LR, 300-WM, and 300-NM. Nothing bedded and all shot fine, until after about 1,000 rounds down-range the action screws in the 300-WM chassis refused to stay tight, even with the new locking washers. No matter how far past the spec'd 60 in/lbs I went, they would loosen after 30-ish rounds fired. Worked with MPA remotely ... no luck on any of their ideas. Rifle went back MPA and the only way Phil could fix the problem, was to bed the chassis ... it's an absolutely beautiful bedding job, by the way. Obviously my MPA 22LR doesn't need any bedding, and thus far with about 800 rounds down-range, the 300-Norma is terrific ... no bedding needed. Explaining why bedding solved a loosening action screw problem is beyond my paygrade, but it worked, MPA stood behind their product, and the rifle is dead-nuts sub-MOA and hits the mile target regularly. That's my story about bedding a chassis. Weird ... eh?

 

[mtnhunter22]

Funny this comes up. Have an XLR

Couple weeks ago I wasn’t stoked with the amount of movement in my BA when removing the front action screw (honestly not sure this plays a role in accuracy. Hadn’t shot the chassis yet.)

Decided to bed it. The damn things are hard to bed. Just a skim bed and chips super easy. But has taken the movement out of the BA when torquing and untorquing. Shooting it this week

 

[chevy_man]

Please explain how the chassis is responsible for zero shifting around when the aiming device, action, and barrel are all 1 unit. Seems like the scope should still be aligned with the barrel?


I've seen lots of rifles in stocks shoot better when free floated and bedded. I've always contributed that to harmonics and pressure points on the barrel since they all had rub marks.


I'd buy the fact that they do shoot better bedded to a chassis sometimes.
I don't buy that it's a common thing for actions to be jumping around in the chassis without it.


It also wouldn't surprise me if the only ones that got bedded were the guys with OCD, and they need everything perfect no matter what. So give them anything and it'll be overkilled.

 

[Baron23]

I have three MPA chassis bolt-action rifles. 22LR, 300-WM, and 300-NM. Nothing bedded and all shot fine, until after about 1,000 rounds down-range the action screws in the 300-WM chassis refused to stay tight, even with the new locking washers. No matter how far past the spec'd 60 in/lbs I went, they would loosen after 30-ish rounds fired. Worked with MPA remotely ... no luck on any of their ideas. Rifle went back MPA and the only way Phil could fix the problem, was to bed the chassis ... it's an absolutely beautiful bedding job, by the way. Obviously my MPA 22LR doesn't need any bedding, and thus far with about 800 rounds down-range, the 300-Norma is terrific ... no bedding needed. Explaining why bedding solved a loosening action screw problem is beyond my paygrade, but it worked, MPA stood behind their product, and the rifle is dead-nuts sub-MOA and hits the mile target regularly. That's my story about bedding a chassis. Weird ... eh?

Glad they fixed you up...but doesn't that sound more like a chassis problem/defect than a need for generalized bedding in chassis?

 

[rustyinbend]

Glad they fixed you up...but doesn't that sound more like a chassis problem/defect than a need for generalized bedding in chassis?

I really didn't care at that point, I just wanted my favorite precision rifle working properly. Phil called me and told me all the stuff they did, and told me that they'd finally solved the problem by bedding the chassis. I suppose if I wanted to be a dick about it, I could have tried to force them to replace the action and maybe the chassis, but frankly, getting a free bedding job and a rifle they described as "completely healed" sounded OK to me. That action and chassis had been awesome until the action screw problem. Was it a defect? Absolutely. Did the manufacturer solve it? They sure did and it's been shooting beautifully ever since. I've even replaced the barrel since then, and it continues to shoot spectacularly ... so I'm OK not holding my breath until they gave me a new action. Now if it happens again on my 300-Norma, or reappears on my bedded 300-WM ... that's when we'll talk about replacing the action and/or chassis.

 

[iceng]

My questions were more about how to bed a chassis,
and the technical answer is...you re-manufacture the chassis...

ie, blow out the "precision" machining, to create space,
the introduce the plastic interface (marine tex, etc)

which raises the point of why not just sell them
this way...ie for real competition shooters...

it would be cheaper and save a couple steps.

Target demographic. Basically a business decision. Many people want a true drop in solution, and dont want too many options to confuse them.

Most (60%+) of customer base want a drop in, no fuss, "go and shoot" solution. 30% want want options, and are happy to tweak as require to get what they want. 10% will go above and beyond and really push the limits change things to get the last 1% of perceved accuracy to satisfy their mental state (example being "less things to worry about").

60/30/10 rule. Cant please everyone, so please the main demographic, but make it compatible enough to work with the rest.

As for the first part, if you (the manuf) put in pre machined cutouts for bedding, 60% of customers would not buy it as they feel obligated to pay to do the bedding job, and as such, they cant go shooting that day with their new expensive toy. Its an "incomplete product" and dont want it.

Most people on this forum are 50% of that small 10% rule, so again, we have bias here.

 

[Tokay444]

Please explain how the chassis is responsible for zero shifting around when the aiming device, action, and barrel are all 1 unit. Seems like the scope should still be aligned with the barrel?


I've seen lots of rifles in stocks shoot better when free floated and bedded. I've always contributed that to harmonics and pressure points on the barrel since they all had rub marks.


I'd buy the fact that they do shoot better bedded to a chassis sometimes.
I don't buy that it's a common thing for actions to be jumping around in the chassis without it.


It also wouldn't surprise me if the only ones that got bedded were the guys with OCD, and they need everything perfect no matter what. So give them anything and it'll be overkilled.

Because you interface with the rifle by the stock/chassis. That’s where you drive it.

 

[Rio Precision Gunworks]

My questions were more about how to bed a chassis,
and the technical answer is...you re-manufacture the chassis...

ie, blow out the "precision" machining, to create space,
the introduce the plastic interface (marine tex, etc)

which raises the point of why not just sell them
this way...ie for real competition shooters...

it would be cheaper and save a couple steps.

As then bedding would be absolutely required. Not just an option or sometimes required.

The point is the whole “you shouldn’t have to bed a chassis” is just another myth that gets propagated continuously. Not that you must or need to bed the chassis.

That’s a very distinct difference.

 

[Rio Precision Gunworks]

Please explain how the chassis is responsible for zero shifting around when the aiming device, action, and barrel are all 1 unit. Seems like the scope should still be aligned with the barrel?


I've seen lots of rifles in stocks shoot better when free floated and bedded. I've always contributed that to harmonics and pressure points on the barrel since they all had rub marks.


I'd buy the fact that they do shoot better bedded to a chassis sometimes.
I don't buy that it's a common thing for actions to be jumping around in the chassis without it.


It also wouldn't surprise me if the only ones that got bedded were the guys with OCD, and they need everything perfect no matter what. So give them anything and it'll be overkilled.

If it worked like that, you’d never have a zero shift when you remove and reinstall a barreled action into a chassis.

Which I don’t think anyone would argue never happens.

You also have different zeros if you use something like an SEB rest and a rabbit ear bag vs a bipod and squeeze bag……with the exact same rifle. So, your rifle zero isn’t just with the barreled action.

 

[-H-]

I’ve never heard of a negative effect on a properly bedded stock/chassis, so how are people surprised that folks are willing to bed them?