MPA 22BA Cleaning Problem

[rustyinbend]

My MPA 300WMBA has a folding stock that gets the cheek rest out of the way for cleaning.
My new MPA 22BA does not ... and the fixed stock and fixed (non-adjustable) cheek rest prevents insertion of a bore guide and prevents use of a normal length cleaning rod. You just can't get a straight shot at the rifle bore.

I've looked for an easy way to separate the chassis back-end, or remove the fixed cheek rest ... but nothing is obvious.

Has anybody solved this problem without major disassembly? Photo below showing what the (canted) bore guide (CZ455) looks like ... proving it's impossible to use under normal conditions.

 

[squishee]

Loosen the set screws and it pulls right off from the top .

 

[Eoddave27]

As Squishee said there should be two set screws for the cheek rest. Once those are lose the check rest pulls right off on mine.

 

[rustyinbend]

It worked. They are tiny - my vision sucks. Thanks.

 

[ScottDWallace]

I take the action out of the chassis for cleaning. That gives me a chance to give the gun a once over, tweak trigger settings, clean the dirt and silt out of the nooks and crannies and makes sure I have good torque for the next outing.

 

[rustyinbend]

I take the action out of the chassis for cleaning. That gives me a chance to give the gun a once over, tweak trigger settings, clean the dirt and silt out of the nooks and crannies and makes sure I have good torque for the next outing.

What is the torque setting on the action screws? Is it different from the settings on my 300 WMBA?

 

[ScottDWallace]

Well, every gun in theory has a perfect action torque which is derived from testing. With my Vudoo, I started with the old standby of 65inlb and the damn thing shoots lights out. Haven't felt the need to tweak that one.

My old Remmy in HS Precision stock was another beast. 55 front, 60 rear.

 

[rustyinbend]

65-ish ... same as the MPA larger chassis ... thanks.

 

[reichco457]

65-ish ... same as the MPA larger chassis ... thanks.

MPA has Thumb Screws to use instead of set screws. I just received my chassis yesterday and had purchase them several weeks earlier . Easy to adjust or remove Cheek Rest. Get another set for the adjustable Butt-Plate.

Regarding Inch Pounds for Action Screws MPA recommends 65 inch/lbs. MPA has multiple videos, there initial set up shows exactly how to do this.

 

[rustyinbend]

MPA has Thumb Screws to use instead of set screws. I just received my chassis yesterday and had purchase them several weeks earlier . Easy to adjust or remove Cheek Rest. Get another set for the adjustable Butt-Plate.

Regarding Inch Pounds for Action Screws MPA recommends 65 inch/lbs. MPA has multiple videos, there initial set up shows exactly how to do this.

Just ordered the thumb-screws, and CZ455 magwell insert. Didn't know either of these were available until you got me looking at the BA-Lite accessories. THANKS!

 

[kl3309]

65-ish ... same as the MPA larger chassis ... thanks.

The rimfire chassis is less heavily built than the CF chassis. If you put that much torque on the action screws, you'll pull the front of the action down into chassis causing the sides of the chassis to splay out. Your barrel will then hit the bridge at the front of the chassis. This has been my experience with the 455 chassis anyways (I'm at ~45 in-lbs on mine).
Kinda not a good thing taking the action out all the time. You'll have to verify your zero afterwards if not re-zero. Also increases the chance of stripping out the screw holes in the action.

 

[ScottDWallace]

Even easier than changing your cheek piece height is to remove the butt stock. One screw and it's done. Which is another critical point to make sure is tight before a match. More than once have I had the butt stock loosen up during a match.

 

[rustyinbend]

Even easier than changing your cheek piece height is to remove the butt stock. One screw and it's done. Which is another critical point to make sure is tight before a match. More than once have I had the butt stock loosen up during a match.

I thought about that, but I looked at the under-side and there's a second screw that is half-covered by the pistol grip. Are there two screws to remove the stock? It sure looks like it, and one of them doesn't appear to come out without removing other stuff. See photos ...

 

[reichco457]

The rimfire chassis is less heavily built than the CF chassis. If you put that much torque on the action screws, you'll pull the front of the action down into chassis causing the sides of the chassis to splay out. Your barrel will then hit the bridge at the front of the chassis. This has been my experience with the 455 chassis anyways (I'm at ~45 in-lbs on mine).
Kinda not a good thing taking the action out all the time. You'll have to verify your zero afterwards if not re-zero. Also increases the chance of stripping out the screw holes in the action.

From assuming that 65 in/lbs based on MPA video for action screws it is not applicable. Assembly of my MPA BA Hybrid for CZ457 last night I discovered it is much lower. The bolt binds once I used higher values for the action screw torque when I get above 47 in/lbs on the rear, and the front at 65. I settled on 44 front and 45 in/ lbs for the action screws, using those settings does not bind the bolt.

 

[rustyinbend]

From assuming that 65 in/lbs based on MPA video for action screws it is not applicable. Assembly of my MPA BA Hybrid for CZ457 last night I discovered it is much lower. The bolt binds once I used higher values for the action screw torque when I get above 47 in/lbs on the rear, and the front at 65. I settled on 44 front and 45 in/ lbs for the action screws, using those settings does not bind the bolt.

I split the difference based on the advice here ... between 45 and 65 in/lbs ... got it at 55 and everything seems to slide nicely. Next range visit, I'll see how it shoots.

 

[ScottDWallace]

I thought about that, but I looked at the under-side and there's a second screw that is half-covered by the pistol grip. Are there two screws to remove the stock? It sure looks like it, and one of them doesn't appear to come out without removing other stuff. See photos ...

View attachment 7267410 View attachment 7267411

I stand corrected. That's what I get for bourbon posting!

 

[rustyinbend]

I stand corrected. That's what I get for bourbon posting!

LOL ... I know the feeling ... I do it all the time.

 

[reichco457]

I split the difference based on the advice here ... between 45 and 65 in/lbs ... got it at 55 and everything seems to slide nicely. Next range visit, I'll see how it shoots.

Soooo this thread got me thinking about the “blanket 65 inch lbs” for the two action screws.
1. Inserted front screw went to 25
2. Inserted rear screw went to 25
3. Front screw to 35, then rear to 35
4. Then alternating action screws in 10 inch lbs increments, continued to check on any bolt binding
5. Got to 55 inch lbs on both, checked on any bolt binding......smooth, no binding.
6. Settled on 55 inch lbs, now to get it to the range, zero it in and make assessments!

 

[rustyinbend]

Soooo this thread got me thinking about the “blanket 65 inch lbs” for the two action screws.
1. Inserted front screw went to 25
2. Inserted rear screw went to 25
3. Front screw to 35, then rear to 35
4. Then alternating action screws in 10 inch lbs increments, continued to check on any bolt binding
5. Got to 55 inch lbs on both, checked on any bolt binding......smooth, no binding.
6. Settled on 55 inch lbs, now to get it to the range, zero it in and make assessments!

Can you give me the details on that cool scope mount? I want one !!!

 

[rustyinbend]

Never mind ... found it ... bought one !!!

 

[reichco457]

Can you give me the details on that cool scope mount? I want one !!!

Bought it from Area 419, it’s 15 MOA. It is intended for CZ 455 or CZ457. The dove tail that is part of the action allows their rail to slide onto to it, and hex heads secure to the dove tail. It’s approx 6” + inches long and allows picatinny clamping of scope rings.

 

[rustyinbend]

My MPA22BA has a CZ455 action, so it's perfect. Just bought one in 15MOA ... the 30MOA seemed a bit extreme for a 22LR.

 

[reichco457]

My MPA22BA has a CZ455 action, so it's perfect. Just bought one in 15MOA ... the 30MOA seemed a bit extreme for a 22LR.

It has a small built in level, good secondary check for Cant

 

[rustyinbend]

It has a small built in level, good secondary check for Cant

Great for when I'm stretching that 22LR round out past 1,000 yards ... eh?

 

[reichco457]

Great for when I'm stretching that 22LR round out past 1,000 yards ... eh?

Yeah, hahaha!

 

[rustyinbend]

Yeah, hahaha!

Here's me with my 22LR making that 1,000 yard shot.

 

[reichco457]

Here's me with my 22LR making that 1,000 yard shot.
View attachment 7269067

Great rifle skills!!

 

[rustyinbend]

Great rifle skills!!

It's all about getting the ballistic drop characteristics right ...