PRS Talk MDT ACC Chassis

[ATEP5F9]

Shot a season of PRS competitions. Debating about upgrading to a MDT ACC chassis system. I prefer this to the MPA system after handling the two, however, I have not been able to shoot with either one.

Any recommendations or suggestions regarding these platforms?

 

[Mormegil87]

Just do it.

I went from an AI rifle, to a custom with an MPA and just now switched to the MDT chassis. It is the most comfortable of the three.

The MDT ACC is essentially the next evolution of the MPA. Between the adjustable buttstock, adjustable grip the weight/balance tuning system, built in barricade stop at the magwell and m-lok for future innovations. Its hard to beat. The price point is pretty competitive.

 

[ATEP5F9]

Just do it.

I went from an AI rifle, to a custom with an MPA and just now switched to the MDT chassis. It is the most comfortable of the three.

The MDT ACC is essentially the next evolution of the MPA. Between the adjustable buttstock, adjustable grip the weight/balance tuning system, built in barricade stop at the magwell and m-lok for future innovations. Its hard to beat. The price point is pretty competitive.

The weight tuning kit really impressed me. Thanks for the info!

 

[Mormegil87]

I've found that the front weights are more important that the rear. The only reason I keep the stock weights is just for when I go from a Marksman to MTU contour.

 

[DisplacedTexan]

I am having to have my ACCs bedded and know a few others that have had to as well. Love the chassis and have two of them, but be aware.

 

[urabus]

I am having to have my ACCs bedded and know a few others that have had to as well. Love the chassis and have two of them, but be aware.

interesting......JP mentioned in one of the podcasts (VP Precision) that he also got his ACC's bedded.
I run both MPA BA Comp and MDT ACC, but I'm having no luck with the ACC.
always thought maybe it's the variation in dimensions of my European 3 lug action with Rem 700 footprint (AS.H Walkure/Nimrod).
will give bedding a try. tks!

 

[Mormegil87]

I am having to have my ACCs bedded and know a few others that have had to as well. Love the chassis and have two of them, but be aware.

What actions are you running?

 

[DisplacedTexan]

What actions are you running?

I'm running a Tempest but the others are running different actions.

 

[Mormegil87]

I'm running a Tempest but the others are running different actions.

I'm running a an Impact and haven't noticed an issue but will be double checking.

Edit: Just double checked mine. No issues with flexing or marrying up to the action

 

[_Raining]

My Rem 700 had problems (4" Vertical stringing). BUT the instructions do say that you should tighten the action after 100 rounds, which I did not do. I have since had it back in my XLR Chassis which is skim bedded (recoil lug and rear tang). I should probably give it another try but if there is still a problem I won't be bedding Rem 700 to it, I will have to decide what action I want to commit to it.

 

[jaybigboy34]

Only thing I don't like about the acc chassis is that the buttstock isn't one piece.

 

[HDEAN20]

I had an ACC but didn't like it as much as I was hoping I would. Just a personal preference/comfort thing. It really checks all of the boxes I have when looking for a chassis. I like the weight tuning. I agree with guys saying the front weights are more important than the rear weights. I think balance is more important than overall weight. Since the ACC I've gone to XLR and will be staying with XLR for a while. Recoil was more dead IMO in the XLR than the ACC even while the ACC was heavier. The XLR buttstock is really light so you don't have to have as much total weight on your rifle to achieve that forward of magwell balance point.

 

[BroncoMustang]

I am having to have my ACCs bedded and know a few others that have had to as well. Love the chassis and have two of them, but be aware.

That's disappointing to read, as I have long admired those stocks. Has anyone else had the same experience, requiring them to have the ACC chassis bedded?

 

[ATEP5F9]

That's disappointing to read, as I have long admired those stocks. Has anyone else had the same experience, requiring them to have the ACC chassis bedded?

Personally I have not. Own an ACC with a Savage action and found improved rigidity and a slight increase in accuracy. Overall good quality product. Great ability to modify the balance of the rifle using the weight kits.

 

[hengehold]

My Rem 700 had problems (4" Vertical stringing). BUT the instructions do say that you should tighten the action after 100 rounds, which I did not do. I have since had it back in my XLR Chassis which is skim bedded (recoil lug and rear tang). I should probably give it another try but if there is still a problem I won't be bedding Rem 700 to it, I will have to decide what action I want to commit to it.

I just bought an MDT ACC stock. Have not been able to use it yet. Posts like these are making me nervous ?.
-TH

 

[DisplacedTexan]

I just bought an MDT ACC stock. Have not been able to use it yet. Posts like these are making me nervous ?.
-TH

Just get it bedded. Mine would shift groups to the right before it got bedded. Sometimes it looked like a shotgun pattern.

 

[NorthWesterner]

Personally I have not. Own an ACC with a Savage action and found improved rigidity and a slight increase in accuracy. Overall good quality product. Great ability to modify the balance of the rifle using the weight kits.

I wouldn’t say I have had this experience. I bed all of my chassis. From what I have found they usually hold just fine under normal shooting. The issues come in when you dump your rifle off of an object on accident and it shifts mid match. This is why I bed mine.

 

[hengehold]

Just get it bedded. Mine would shift groups to the right before it got bedded. Sometimes it looked like a shotgun pattern.

That sounds like a significant design flaw if you see groups shifting for opening up and someways. I have used a V block with a round action to bed rifles that I compete with. A round action bedded into AV block is consistent enough to be competitive in other disciplines (Palma and 1,000yd) at an international level.
I have several rifles I did with the blocks that I use for international Shooting and I have never had a single problem with groups opening up or zeros shifting.
-TH

 

[TeamPOI]

Have you checked out the new MPA Matrix?

 

[BroncoMustang]

The new MPA (MasterPiece Arms) Matrix chassis looks very nice, and I like the thumb-hole opening. Bet they sell a lot of them.

Above is an easily found video about it on YouTube. Also, I like that they provide customized hand grips.

 

[TeamPOI]

The Matrix is amazing!

 

[bschneiderheinze]

Manners

 

[dgheriani]

I've been running ACCs for about as long as they've been in existence with 3 different actions (Rem 700, Deviant Elite and a Nucleus) and have had zero issues and have never bothered to bed them. Even pulling the actions out of the chassis and swapping barrels/calibers around my new zero is almost always within 0.1 of what I have it written down as. Certainly doesn't hurt to bed a chassis though.

 

[anotherwannabe]

@dgheriani are you putting any kind of locknut/washers on the action screws or blue licktite? or just 65 inch pounds and calling it good. the MPA’s come with those little click lockers, ACC is just straight bolts.

 

[dgheriani]

@dgheriani are you putting any kind of locknut/washers on the action screws or blue licktite? or just 65 inch pounds and calling it good. the MPA’s come with those little click lockers, ACC is just straight bolts.

With my Defiance Deviant Elite, I have just straight bolts torqued to 65in/lbs and with my Nucleus I use washers and 65 in/lbs. Washers don't hurt but I was honestly too lazy to source longer action screws for my Defiance and there's been zero issues so I don't screw with it. I've never had an issue with the action screws coming loose with either action and just to be sure, I witness mark (with paint pen) the screws in the chassis.

 

[anotherwannabe]

As long as they don’t come loose, they’re doing their job ?

I just 65 torqued mine but only have about 200 rounds it, so far so good

 

[Gunfighter716]

With my Defiance Deviant Elite, I have just straight bolts torqued to 65in/lbs and with my Nucleus I use washers and 65 in/lbs. Washers don't hurt but I was honestly too lazy to source longer action screws for my Defiance and there's been zero issues so I don't screw with it. I've never had an issue with the action screws coming loose with either action and just to be sure, I witness mark (with paint pen) the screws in the chassis.

I have my Deviant Elite mounted in an ACC with the bolts and washers that came with the chassis. Were the bolts that came with your ACC too short to use the washers with the Deviant Elite?

 

[dgheriani]

I have my Deviant Elite mounted in an ACC with the bolts and washers that came with the chassis. Were the bolts that came with your ACC too short to use the washers with the Deviant Elite?

Mine was one of the real early ones, before they came with washers.

 

[1clicktrick]

How would one who doesnt have a chassis right now choose between the Mdt Acc or the Mpa matrix? Both look great!

 

[b2lee]

How would one who doesnt have a chassis right now choose between the Mdt Acc or the Mpa matrix? Both look great!

You can drive 10hrs and 49mins to my house and shoot the MDT ACC...then drive where ever and shoot the MPA.....and then decide which one you fancy the best. Probably an ACC closer to you though

 

[kthomas]

How would one who doesnt have a chassis right now choose between the Mdt Acc or the Mpa matrix? Both look great!

I wouldn't - I would choose a JAE or the new KRG Whiskey-3 competition chassis

 

[TeamPOI]

How would one who doesnt have a chassis right now choose between the Mdt Acc or the Mpa matrix? Both look great!

Simple!! just pick the Matrix!

 

[generalzip]

Any chassis that touches my action gets bedded. Have seen too inconsistencies that went away after bedding to ever consider not doing it. Survey the top 50 PRS shooters on if they need their comp rifles or not. I bet 80%+ say they do...

 

[kthomas]

Any chassis that touches my action gets bedded. Have seen too inconsistencies that went away after bedding to ever consider not doing it. Survey the top 50 PRS shooters on if they need their comp rifles or not. I bet 80%+ say they do...

Obviously depends on how the action and chassis interface. The end user will have to test their system and ultimately decide what is needed for their system.

Thankfully I haven't found a need to bed my rifles in JAE chassis. I can pull the barreled action and re-install, and POI is within 0.10 mils or less. No change in POI shifts throughout days or weekends of shooting and bumping the gun around. Consistent 1/3-1/2 MOA (and occasionally better) shooters with my reloads.

I don't have any MDT chassis so I can't specifically speak to them. But the end user needs to test and determine from there what they need. It doesn't matter what a bunch of PRS shooters do.

 

[generalzip]

Obviously depends on how the action and chassis interface. The end user will have to test their system and ultimately decide what is needed for their system.

Thankfully I haven't found a need to bed my rifles in JAE chassis. I can pull the barreled action and re-install, and POI is within 0.10 mils or less. No change in POI shifts throughout days or weekends of shooting and bumping the gun around. Consistent 1/3-1/2 MOA (and occasionally better) shooters with my reloads.

I don't have any MDT chassis so I can't specifically speak to them. But the end user needs to test and determine from there what they need. It doesn't matter what a bunch of PRS shooters do.

I own 2 MDT ACC chassis and MPAs. They all improved with bedding. While I agree it doesn’t matter WHAT others are doing you should look and think as to WHY they are doing it. All the good shooters I speak with have all come to the same conclusions on this topic. Coincidence? Up to you to decide. For me, I’ll have them bedded and have the peace of mind at a 2 day match my zero hasn’t shifted between days or bouncing around in a buggy.

a good test is to shoot a group then smack the shit out of your barrel with a mallet and shoot another group. If you see a POI shift your rifle will benefit from bedding it. I’ve found aluminum “chassis” systems have this issue much more. Stocks like a foundation seem to do well without bedding, but most guys I know still skim Bed it at least for the peace of mind.

 

[kthomas]

I own 2 MDT ACC chassis and MPAs. They all improved with bedding. While I agree it doesn’t matter WHAT others are doing you should look and think as to WHY they are doing it. All the good shooters I speak with have all come to the same conclusions on this topic. Coincidence? Up to you to decide. For me, I’ll have them bedded and have the peace of mind at a 2 day match my zero hasn’t shifted between days or bouncing around in a buggy.

a good test is to shoot a group then smack the shit out of your barrel with a mallet and shoot another group. If you see a POI shift your rifle will benefit from bedding it. I’ve found aluminum “chassis” systems have this issue much more. Stocks like a foundation seem to do well without bedding, but most guys I know still skim Bed it at least for the peace of mind.

Well said, and I agree with all of this.

 

[b2lee]

Did you reach out to MDT before you came here to bad mouth them? My action and ACC fit like yoga pants on a cheerleader. Sorry for your bad impression of them.

 

[kthomas]

I just received my MDT ACC yesterday and upon making up the action, I could feel there is an issue in the machined inletting. There's increasing resistance before the screws go to valued torque as I believe it's flexing the action. On my bravo there's very little resistance to making up action screws then tension spikes as it's bottomed against bedding block. My bedded stocks make up same way. I'm kinda pissed I paid 1200$ for a chassis they can't even inlet properly, f'n joke to be honest. I'll have to bed it as well.

While I see how that can be frustrating, MDT has some of the best customer service in the business and I'm confident that they will do what they can to make you a happy customer. Sometimes action screws need to be trimmed or shimmed, that's not unique to MDT.

Reach out to MDT for a resolution, that would be more productive and beneficial then venting on this forum.

 

[generalzip]

Any chassis you want the most consistency from should bedded. Wouldn’t even consider a unbed chassis after what I’ve seen and know now for a competition rifle.

 

[hengehold]

Any chassis you want the most consistency from should bedded. Wouldn’t even consider a unbed chassis after what I’ve seen and know now for a competition rifle.

I have shot rifles (and so have my teammates) that were competitive at the international level for Palma matches. Chassis,V-blocks, and barrel clamp mounts. All successful at the highest levels of international competition out to 1,000yds. I respectfully disagree, and submit that Bedding is NOT necessary for chassis when they are designed properly.

just my .02

-TH

 

[generalzip]

It’s not a big deal if you zero your rifle then immediately go shoot several strings. Bedding seeS an advantage when you zero a rifle then bang it around, drive in a truck for 10 hours over bumpy roads, drop it on the ground, and then shoot another group. Ask me how I know. A Palma match is NOT a prs match. Not even close.

What you don’t know sometimes is just that. What ya don’t know. If there’s a possibility a non bedded rifle can affect your consistency but everyone unanimously agrees bedding it at the very least will not hurt anything, why on earth would you not bed it? Seems like common sense to me.

 

[hengehold]

It’s not a big deal if you zero your rifle then immediately go shoot several strings. Bedding seeS an advantage when you zero a rifle then bang it around, drive in a truck for 10 hours over bumpy roads, drop it on the ground, and then shoot another group. Ask me how I know. A Palma match is NOT a prs match. Not even close.

What you don’t know sometimes is just that. What ya don’t know. If there’s a possibility a non bedded rifle can affect your consistency but everyone unanimously agrees bedding it at the very least will not hurt anything, why on earth would you not bed it? Seems like common sense to me.

I have used bare V-blocks and V-blocks with glass bedding included. I did not notice a difference in performance (precision or zero shift) between the two. My point is that not all chassis need bedding to perform well.

-TH

 

[generalzip]

Again depends on your definition of “perform”. Johnny deer hunter and a top 5 PRS shooter have different definitions and expectations I assure you. Regardless the point I’m making is to advise someone to not bed a chassis would be ultimately doing them a disservice if their goal is maximum precision and consistency in their rifle system

 

[BoltActionBrotherhood]

Are you guys bedding your own chasis? Anyone know of a good tutorial for the aCC in particular?

 

[mtnhunter22]

Following

 

[Dthomas3523]

Are you guys bedding your own chasis? Anyone know of a good tutorial for the aCC in particular?

I just have a smith do it. It’s not expensive and it helps a small business.

The “shouldn’t” need to bed is akin to the “shouldn’t” need to adjust MV in a ballistics solver. Perfect world scenarios. There’s a lot of shouldn’t in a perfect world that just ain’t the case.

The only time I don’t bed a chassis is when I’m deciding which rifle I want to run it in and I’m swapping actions around. Once it had and assigned rifle, it gets bedded. We do all kinds of other small things, no reason not to do another cheap and simple option.

 

[anotherwannabe]

For above asking about bedding an MDT ACC - here you go...
Not the most perfect work, but considering I'd never bedded a rifle before, I'm not crying about it either. Most of the imperfections in the bedding are actually from too much wax buildup on the action that I didn't wipe "smooth" because I was nervous about gluing my action to my chassis.

Step 1 - you can clearly see the (small) contact areas with the chassis. Remember, this is by design on a chassis rifle. Either you have the chassis machined perfectly to cradle a round action (what bedding does), or the action can only have a single waterline of contact against the vblocks. Its why chassis are awesomely interchangeable, but still have minimal contact area with the action.



Step 2 - Dremel made quick work of grinding cerakote and dimpling/checkering the aluminum to give the epoxy more surface area and "texture" to bind to. I probably could have gone "deeper" in hindsight, but grinding up this nice chassis to fit it to a specific action was a bit tough to swallow. I taped off the areas where I didn't want epoxy flowing, used Johnson paste wax on everything, and straws as dam in the action holes. Read up on some bedding threads and all this stuff is pretty straight forward.

Because I was nervous sally - i actually bedded it with plumbers putty once as a practices run, so I could then scrape off the putty (don't forget it leaves a grease film behind) to see approximately how much epoxy I really needed. For a skim bed like this, its a whole lot less than you'd think!



Step 3 -Mix up your slow set epoxy (I used JBWeld 24hr cure) and apply it on there after triple checking you've waxed any and everything that could come intocontact with it.



Step 4 - use electrical tape, surgeons tube, or in my case when neither of those would hold the action without the barrel torquing it, I waxed the action screws and just installed them with my fingers until I saw epoxy flowing/squeezing from tension. Don't torque them down with a wrench.

Didn't take pictures here because I was nervous about getting extra epoxy off, etc. Acetone cleans epoxy and doesn't hurt cerakote, wipe up liberally.

Step 5 - Check the leftover epoxy as it hardens because that is how hard the epoxy in the action will be. Once its "hard enough", but still just barely pliable enough to cut with a knife/razor/utility, thats when I popped my action out to clean up any squeeze out around the lug, in the magwell, etc. That was basically overnight 8 hours for me. Then I put the action back in as before, finger tightened the screws and waited another day before finally taking it out, cleaning up all the wax, etc.





Step 6 - Miller time if you didn't totally fuck up your thousand dollar chassis.

Hope that is useful for anyone who is considering DIY.

 

[BoltActionBrotherhood]

For above asking about bedding an MDT ACC - here you go...
Not the most perfect work, but considering I'd never bedded a rifle before, I'm not crying about it either. Most of the imperfections in the bedding are actually from too much wax buildup on the action that I didn't wipe "smooth" because I was nervous about gluing my action to my chassis.

Step 1 - you can clearly see the (small) contact areas with the chassis. Remember, this is by design on a chassis rifle. Either you have the chassis machined perfectly to cradle a round action (what bedding does), or the action can only have a single waterline of contact against the vblocks. Its why chassis are awesomely interchangeable, but still have minimal contact area with the action.

View attachment 7292990

Step 2 - Dremel made quick work of grinding cerakote and dimpling/checkering the aluminum to give the epoxy more surface area and "texture" to bind to. I probably could have gone "deeper" in hindsight, but grinding up this nice chassis to fit it to a specific action was a bit tough to swallow. I taped off the areas where I didn't want epoxy flowing, used Johnson paste wax on everything, and straws as dam in the action holes. Read up on some bedding threads and all this stuff is pretty straight forward.

Because I was nervous sally - i actually bedded it with plumbers putty once as a practices run, so I could then scrape off the putty (don't forget it leaves a grease film behind) to see approximately how much epoxy I really needed. For a skim bed like this, its a whole lot less than you'd think!

View attachment 7292992

Step 3 -Mix up your slow set epoxy (I used JBWeld 24hr cure) and apply it on there after triple checking you've waxed any and everything that could come intocontact with it.

View attachment 7292996

Step 4 - use electrical tape, surgeons tube, or in my case when neither of those would hold the action without the barrel torquing it, I waxed the action screws and just installed them with my fingers until I saw epoxy flowing/squeezing from tension. Don't torque them down with a wrench.

Didn't take pictures here because I was nervous about getting extra epoxy off, etc. Acetone cleans epoxy and doesn't hurt cerakote, wipe up liberally.

Step 5 - Check the leftover epoxy as it hardens because that is how hard the epoxy in the action will be. Once its "hard enough", but still just barely pliable enough to cut with a knife/razor/utility, thats when I popped my action out to clean up any squeeze out around the lug, in the magwell, etc. That was basically overnight 8 hours for me. Then I put the action back in as before, finger tightened the screws and waited another day before finally taking it out, cleaning up all the wax, etc.

View attachment 7293004

View attachment 7293005

Step 6 - Miller time if you didn't totally fuck up your thousand dollar chassis.

Hope that is useful for anyone who is considering DIY.

THANK YOU

 

[Qwack]

Zombie thread, I know. Please don't eat my brain...

I have three chassis rifles. All 700 clones. On two of these, I bedded the tang area. Didn't touch the third yet. I'm thinking of a full bedding job on this one. It's an ACC.

For those who bed their chassis: Do you only do front and back like #anotherwannabe, or do you bed the central portion of the action that sits over the magwell?

Thanks !