Gunsmithing Bedding a MPA BA Chassis

Hoyt7mm

Bow Shooter
Supporter
Full Member
Minuteman
Supporter+
Apr 6, 2017
659
166
Wisco
Has anyone bedded an MPA chassis before? Did you dremel out the v blocks at all? It looks like I should have room for a thin layer to tighten everything up but want to make sure. I've done a few stocks before, but this is my first chassis bed job (other than recoil lug).
Thanks!
 

delfuego

Belieber
Full Member
Minuteman
Aug 21, 2011
857
392
In Limbo
Since no one has chime in, I will add my 2 cents. I know exactly where you are coming from. I moved my Bighorn TL2 from an XLR to an MPA recently. The XLR is precisely machined to match the action. Kyle @ XLR does not screw around. I let him know my action was a trim-tang TL2 and it fits like a glove. When I switched to the MPA and bolted the action in, there was a void under the action. I was worried and contacted Al @ MPA. I took photos with feeler gauges under the action to show the size of the void. Al had me tape the inside of the action with painters tape and rebolt the action in. This showed the contact points of the MPA and the action. Al assured me this was correct because MPA uses a "V-Block" in their chassis. I proceeded to reinstall the action and torqued the bolts in sequence according to their manual. I have not had any issues and the rifle shoots awesome.

I think that "skim bedding" the MPA under the tang and under the action behind the recoil lug may not be a bad idea. It would help to distribute the stress/weight of the action within the V-Block. That being said, I will not be bothering with this. The 2 reasons are; the rifle shoots great and if I sell the stock the it would essentially be custom for that specific action. You may choose to do this and I highly doubt it would have an adverse effect on accuracy (if done properly), I just don't think you will gain much after the investment of time and or money. I shoot PRS/NRL type matches, I do not shoot BR or F-Class. This chassis is not for Benchrest shooting, so gaining a tiny bit more accuracy is not going to help my scores. If I was shooting F-Class and really wanted to wring all the accuracy out of this setup, I may entertain the idea of bedding this chassis.
 

Sheldon N

Blind Squirrel Finds a Nut
Full Member
Minuteman
Sep 24, 2014
4,103
3,597
Pacific Northwest
I'm not normally a fan of bedding a chassis. Like mentioned above, you hurt the resale value and limit the flexibility of the system, and if the gun is shooting there's no reason to mess with it. I've had chassis guns shoot awesome with no bedding.

However, I did just bed my MPA TL-3 combo. Was getting vertical stringing on target, group sizes from the MPA were larger than from another chassis system when I swapped the barreled action from one to the other, and looking at the recoil lug pocket in the MPA it was clear that I didn't have even contact, there was a fine line worn at the bottom of the edge of the recoil lug and no marks above.

Bedded it with some marine-tex in the recoil lug and tang area. Prepped the chassis by sanding with 60 grit and roughing up the V-block surface with a dremmel tool to take off some of the cerakote. Turned out great and after cleaning everything up the gun is shooting as it should now. I left the V-block point of contact pretty much untouched other than to get them roughed up and remove cerakote, so when you look at the bedding you see the V block point of contact showing through the bedding, with support structure all around.
 

LC 6.5 Shooter

Apollo 6 Creed
Supporter
Full Member
Minuteman
May 29, 2018
1,216
183
League City, TX
Has anyone bedded an MPA chassis before? Did you dremel out the v blocks at all? It looks like I should have room for a thin layer to tighten everything up but want to make sure. I've done a few stocks before, but this is my first chassis bed job (other than recoil lug).
Thanks!

Old post but did you skim bed the MPA Chassis? Thinking of doing mine. I think it should be shooting better.

Gary
 

Hoyt7mm

Bow Shooter
Supporter
Full Member
Minuteman
Supporter+
Apr 6, 2017
659
166
Wisco
Old post but did you skim bed the MPA Chassis? Thinking of doing mine. I think it should be shooting better.

Gary
I did. Seemed to help a bit. In the end, I think it was more just my comfort with the chassis. I love everything about it, but for some reason I am more comfortable with a regular stock like Manners/McMillan, so I swapped out to a T4A.
 

LC 6.5 Shooter

Apollo 6 Creed
Supporter
Full Member
Minuteman
May 29, 2018
1,216
183
League City, TX
Im really comfortable on mine. Had a great weekend at the range with a friends 6brx and .300 win mag shooting phenomenal groups. My MPA has a 26” Hawk Hill in 6.5cm chambered by PVA and has shot good. Been getting groups in the .4-.7 range on mine. Figured that was good and the rifle shot better than I could. Then I shot mine after the other 2 and proceeded to really suck on mine after shooting one hole groups. Guess I searching for a reason not to blame myself lol. I do feel a HH chambered by PVA should shoot really tight.
 

Missioncarpenter

Private
Minuteman
Jun 7, 2020
27
7
Since no one has chime in, I will add my 2 cents. I know exactly where you are coming from. I moved my Bighorn TL2 from an XLR to an MPA recently. The XLR is precisely machined to match the action. Kyle @ XLR does not screw around. I let him know my action was a trim-tang TL2 and it fits like a glove. When I switched to the MPA and bolted the action in, there was a void under the action. I was worried and contacted Al @ MPA. I took photos with feeler gauges under the action to show the size of the void. Al had me tape the inside of the action with painters tape and rebolt the action in. This showed the contact points of the MPA and the action. Al assured me this was correct because MPA uses a "V-Block" in their chassis. I proceeded to reinstall the action and torqued the bolts in sequence according to their manual. I have not had any issues and the rifle shoots awesome.

I think that "skim bedding" the MPA under the tang and under the action behind the recoil lug may not be a bad idea. It would help to distribute the stress/weight of the action within the V-Block. That being said, I will not be bothering with this. The 2 reasons are; the rifle shoots great and if I sell the stock the it would essentially be custom for that specific action. You may choose to do this and I highly doubt it would have an adverse effect on accuracy (if done properly), I just don't think you will gain much after the investment of time and or money. I shoot PRS/NRL type matches, I do not shoot BR or F-Class. This chassis is not for Benchrest shooting, so gaining a tiny bit more accuracy is not going to help my scores. If I was shooting F-Class and really wanted to wring all the accuracy out of this setup, I may entertain the idea of bedding this chassis.
Thank you for your input. I'm having trouble getting mine to shoot one hole groups consistently. I have sent my rifle to Lapua for lot testing. I do shoot f class rimfire and benchrest rimfire. The strange thing is...i have to tune the action screws to 42 lbs on the front and 32 lbs on the rear. Not sure if that's bad? I was getting vertical stringing and was trying to close that up. So...im gonna try it. Thanks
Richard
 
  • Like
Reactions: delfuego

Gray

Gunny Sergeant
Full Member
Minuteman
Apr 28, 2011
1,242
4
37
Garner, NC
I epoxy bed a lot of MPA Chassis because receiver fit can be an issue. It will fix issues with vertical and horizontal stringing as well as give you consistent return to zero after removing barreled action for maintenance.

1598721519898.jpeg

Gray Sloan
Swift Creek Rifles
 
Last edited:
  • Like
Reactions: Missioncarpenter

Missioncarpenter

Private
Minuteman
Jun 7, 2020
27
7
I epoxy bed a lot of MPA Chassis because receiver fit can be an issue. It will fix issues with vertical and horizontal stringing as well as give you consistent return to zero after removing barreled action for maintenance.

View attachment 7410954
Gray Sloan
Swift Creek Rifles
Gray. Thank you for your advice and the picture. I bought a wheeler kit from Midway a few years ago but could not see where to put the bedding because of the v blocks or felt it would not help. I can't tell you how much trouble I've had and how many different combinations I have tried. I'm gonna try this today. Thanks
Richard
 

Missioncarpenter

Private
Minuteman
Jun 7, 2020
27
7
HEY Gray! Looks like you put the bedding down the sides too? This is my Vudoo receiver and I can barely get a dollar bill down the side. Should the bedding touch the receiver there? And the front of your lug looks different too? I thank you in advance!
Richard
 

Attachments

  • 1598790962133395568052.jpg
    1598790962133395568052.jpg
    427.5 KB · Views: 102

Gray

Gunny Sergeant
Full Member
Minuteman
Apr 28, 2011
1,242
4
37
Garner, NC
HEY Gray! Looks like you put the bedding down the sides too? This is my Vudoo receiver and I can barely get a dollar bill down the side. Should the bedding touch the receiver there? And the front of your lug looks different too? I thank you in advance!
Richard
I fully bed the action all the way around on a chassis, not just the lug area. A dollar bill will fit because the v block is contacting a small portion of the action. Epoxy will fill that portion in and support the action 100%.
 

Beachhead192

Supporter
Supporter
Minuteman
Aug 28, 2020
55
27
This falls into the "why bother" category for me. My MPA chassis rifle shoots well, and it has for years.
 

Missioncarpenter

Private
Minuteman
Jun 7, 2020
27
7
I fully bed the action all the way around on a chassis, not just the lug area. A dollar bill will fit because the v block is contacting a small portion of the action. Epoxy will fill that portion in and support the action 100%.
Thanks Gray. I had a gunsmith do it because i was a little concerned about doing my benchrest rifle for a first time. I was disappointed that he told me when I dropped it off that he only does the lug area and the rear. Its shooting a lot better so I'll go with it for now.