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  #1  
Old 12-23-2018, 06:41 PM
fartblossom1953 fartblossom1953 is offline
 
Join Date: Oct 2009
Location: Newport N.C.
Posts: 771
Default Sudden change in impact point

Have a 2.88 mil Underwood with a flip sight. After filing a little from the front sight to match my hand loads it shot gold at the Eastern Games and I was happy. When I took it back the next year it was shooting 10 or 11 inches high and I can't reliably adjust to that much aiming off. The tall rear sight is filled in to preclude mistakes so that's not the problem. If I remove the type 1 band and the rear screw it will rock up and down just forward of the mag well. Any help with what to relieve or address would be appreciated. Front sight is now .250 marked SI U and rear plate is marked AU and fits very tight. I would like to try it again this year at the games but won't remove the original stuff just for a match.
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  #2  
Old 12-23-2018, 07:41 PM
fartblossom1953 fartblossom1953 is offline
 
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Location: Newport N.C.
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That's a possibility. I do remember closing the recoil lug up some and now it's so tight on the receiver I remove the action with it on and knock it off to remove it. Too tight maybe?
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  #3  
Old 12-23-2018, 09:02 PM
fartblossom1953 fartblossom1953 is offline
 
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Location: Newport N.C.
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Definitely does not go in easy. So difficult to get in or out I remove the band and rear screw so not to mess something up prying barrel up or pushing it down. I think I might need to get a different one that I have not squeezed a bit.
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  #4  
Old 12-23-2018, 09:57 PM
1hdrocks 1hdrocks is offline
 
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Location: Illinois
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FB, have you tried bumping the butt of the stock on the floor or bench (padded of course) as you tighten the recoil plate screw ?
When reassembling I set the action in the the stock, tighten the screw a little, bump the buttplate , tighten a little more, bump the butt, tighten a little more, bump the butt, etc until things are tight. Read about this here on the forum years ago and it has seemed to work well for me. Seems to get things seated in their place as ya tighten her down. Might be voodoo for all I know???
Guess I should ask, did you close up the recoil plate after winning Gold or prior ?
Should also give kudos for getting it closed a bit without breaking it, some of them will break like glass.

Last edited by 1hdrocks; 12-23-2018 at 10:03 PM.
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  #5  
Old 12-24-2018, 05:34 AM
Kerz Kerz is offline
 
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http://thecmp.org/wp-content/uploads...Notes_2007.pdf
http://thecmp.org/cmp_sales/rifle_sales/m1-carbine/
Some good info provided by CMP
Vic
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  #6  
Old 12-24-2018, 07:27 AM
fartblossom1953 fartblossom1953 is offline
 
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Location: Newport N.C.
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I went ahead and ordered another recoil plate marked AU like the original and will play with it some more. I did use a screwdriver to loosen both screws yesterday and the group came 2 or 3 inches closer to the POA but was still 8 to 11 inches high. Tightening the screws raised it back up. After I try it with the new (used) plate I'll see what else it could be. Thanks for the references Kerz, that's the info I used for assembly. Still scratching the old noggin but will keep pluggin away at it.
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  #7  
Old 12-24-2018, 11:18 AM
6 Ring 6 Ring is online now
 
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A tight recoil plate is what you want. There is a method for assembling a carbine if the recoil plate has been removed.
Put the recoil plate in the stock not tight but it can just move.
Put the B/R in the stock. You should have to hit the butt plate with the palm of the hand to get the receiver lug into the recoil plate. If the receiver flops into the stock and recoil plate, the recoil plate is too loose.
Now with the receiver in the recoil plate, little or no crack and they are straight with each other, tighten down the recoil plate screw. Not dog tight or all you will do is crush wood under it.
If the B/R comes up when the recoil plate screw is tightened down, bump it more into the recoil plate. This is a good thing, you have a tight recoil plate.
Now, the recoil plate is in line with the receiver. On some stocks, if the recoil plate is just tightened down with out the B/R in it, there is a little wiggle room in the wood and the recoil plate and received cannot be in line with each other. On some worn carbines, you can pull the barrel and the receiver goes in and out in the recoil plate. This is way too loose.
Now with the recoil plate tightened down, remove the B/R.
Now put the B/R back in. The barrel should be about a half an inch +/- above the stock nose. This tells you the recoil plate is tight enough and will hold the receiver when it goes all the way in. As said if the B/R flops in the recoil plate and stock is too loose.
Now this the important part, with a little pressure squeezing the barrel to the stock nose with the left hand, hit the butt plate with the palm of the right hand to seat the receiver lug into the recoil plate. It may take several hits to seat it. On a very tight recoil plates, I have had to hit the floor with the butt plate, bang the stock down several times to get the receiver into the recoil plate. Your recoil plate is too tight only if you can not get the receiver lug into the recoil plate by beating the butt plate on the floor. I have had some very tight recoil plates and it took several floor hits to get it in, but I have never had one too tight.
Once the B/R is in the stock "NO" pressure should be needed to put the HG and band on.

Now what happens went the B/R is assembled, with pressure pushing the barrel down as someone stated above. First you are crushing wood under the recoil plate and the first or second shot with seat the receiver lug into the recoil plate all the way and the point of aim will change.
Hitting the butt plate should be required every time to get the barrel into the barrel channel of the stock each time the B/R is removed from the stock.
If the recoil plate is removed, the whole thing has to be done again. Aligning the recoil plate is a important part of carbine assembly. If there is any "pressure" on the barrel from the band, like holding it down, as the barrel heats up the point of aim will move.

Last edited by 6 Ring; 12-24-2018 at 03:07 PM.
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  #8  
Old 12-24-2018, 12:24 PM
fartblossom1953 fartblossom1953 is offline
 
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Location: Newport N.C.
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Thank you 6 RING. The action will not currently install in the plate even with banging on the floor. I have to remove the action with the plate stuck to it and knock it off with a plastic hammer. It will only go back on the same way. If I pull up on the barrel to remove the action once it's in it feels like I'm going to bend the screw or break some wood. It used to be too loose as you described and now I think it might be too tight?
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  #9  
Old 12-24-2018, 12:40 PM
meplat meplat is offline
 
Join Date: Jan 2010
Location: Prescott, AZ
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Thare's been literally tons of posts here regarding recoil plate fitment. Although there should be "some resistence" to pulling the barrel up out of the stock (i.e. it shouldn't just "pop up" when removing the handguard), it sounds like your recoil plate "pinches" your receiver lug too tightly.

Another possibility, since you say it originally "shot gold" and a year later its POI is radically different, maybe the wood "dried out" (i.e. warped)? Just a thought.




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  #10  
Old 12-24-2018, 12:57 PM
1hdrocks 1hdrocks is offline
 
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6 Ring, thank for a much better explanation of this procedure. Might have even read that from you years ago. All I know is it seems to work so I’ve always done it since I read about it. Thanks again.
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