Did my stock shrink?

Spearhunter

Spearhunter

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I have an M305 with the black plastic stock. I stripped the rifle about a month ago and didn't put it back till now. Tonight I also installed a Leapers UTG rail and began to assemble it. Everything was fine until I tried to put the receiver back in the stock. I found the tang at the bottom of the receiver seems to be just a touch off it's slot in the stock.

Here's how it looks:
http://lh5.ggpht.com/_7Z-2bxymqdI/S2uxDMttJbI/AAAAAAAAF98/cC5DQuQ5QjE/s800/IMG_0099.JPG

Close up:
http://lh5.ggpht.com/_7Z-2bxymqdI/S2uxDULwIgI/AAAAAAAAF-A/fegfiO2Nr00/s800/IMG_0098.JPG

Other side:
http://lh4.ggpht.com/_7Z-2bxymqdI/S2uxC7Nl4XI/AAAAAAAAF94/JKAGTH3tVSw/s800/IMG_0100.JPG

Has anyone experienced this? What can be done?

Thanks.

SH
 
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Are the side rails of the utg installed? And if so, are they binding on the stock?
Try removing them and insstalling the stock
Could just be a very snug stock. Many of the polys I've been working on have very tight fitting stocks
 
Jesskf: Actually the tang is slightly ahead of the slot so I need to be able to move the receiver BACKWARDS. Problem is that it is jammed tight against the front barrel clip.

M14Doctor: No the side rails are not installed. The mount does not seem to be in the way and at it's current position, it has not come in contact with the stock.

I thought about jamming it in but am afraid I might bend the metal guide in the stock. It was tight & snug in the past but not like this.
 
Was it warmer when the stock was removed? not sure what the coefficient of thermal expansion is on plastics...
 
No...still room temp. but that is a good point. Is it possible that from the factory, the rifle was assembled and the stock allowed to shrink for a tight fit? I'm not sure if plastic will contract that much but maybe the month long period the receiver was out has a detrimental effect? A wild idea at the very least.

But bottom line is...what do I do? Any other suggestions out here? Maybe I should heat the stock?
 
Is there any indication in the internal surfaces of the stock as to what plastic it is?

Some plastics can be susceptable to humidity (or lack thereof) - perhaps difference between south china in summer and ontario in winter? Nice warm bath (for the stock)could kill two birds with one stone and would be where I'd start if it happened to me.
 
Undo the metal liner side screws, then try again
If rifle goes in fine , instal the screws
I dunno about heating the stock....
 
I thought about lightly "toasting" the stock in the oven but that is probably a stupid idea. Maybe I'll leave the receiver outdoors and see if it contracts.

There seems to be no markings on the stock as to what type of plastic it is. I'll also try removing the metal liner screws if I can find some way to turn it.
 
I thought about it but there's just not enough clearance. If it were just tight I could try...drats what I thought could remove the stock liner screw didn't fit. I'll take the rail off and see if it makes a difference.
 
Well, I had a client drop a rifle off for work this morning.
It' a new polytech and suffers this same problem.
What I have found is at issue is the distance from the stock metal insert receiver bearing surface to the stock ferrule at the nose of the stock is wrong and is millimeters over spec. Causing the stock ferrule to press tight against the gas cylinder band and preventing the receiver lugs from aligning with the stock metal bearing surfaces.
This BAD.... Very bad.
I can't explain the steps to remedy this, it involves either removing and relocating the metal liner or better yet, removing the stock ferrule and milling the stock so as to relocate the ferrule far enough back to allow the stock to fit the action AND (very important) there MUST be a small gap between the stock ferrul metal and the gas band plate where the nose of the stock engages.
I wonder how widespread this is with the PolyPlastic stocks.
 
One more thing.... In the abscence of a stock liner screw removal tool, take 2 finishing nails, head end sticking forward and grasp with locking vice grips. Clamp them with the vicegrips with approx spacing of the holes in the liner screws.
Kinda micky mouse but it works :)
 
M14 Doctor, thanks for the tip on the stock liner screwdriver. You brought up a very interesting point. Since I took the gas lock off when replacing the hand guard, I wonder if the UTG rail is shorter, just a bit and enough to change the distance between the receiver and the nose of the stock.

Now for an update. Just before taking off the rail, I decided to test me theory about "shrinkage". I left the stock in the garage to cool off (contract) and placed the receiver by the floor register where hot air from the furnace was flowing (expand). A few hours later I gave it a try and it went in! I can't really say for certain that it helped but I'm just glad it resolved the problem.
 
To add another suggestion in the absense of a stock liner removal tool.. needle nose pliers. Use a cheap Crappytire set if you can, because you have to twist on it pretty good.
 
You should be able to get spanner bits from any hardware/tool store. Look for "security screwdrivers" or bit sets/multi screwdrivers etc. The two holes type is called a spanner type. There are many different sizes that are usually quite similar, i.e. a number 6 will work in a number 8 but slip off a lot, so if you can bring the stock with you or measure the distance from center to center and grab the right size, or grab a complete kit. They range anywhere from 14 bucks for a complete chinese made kit to 60, on the other hand a single screwdriver of this type can also cost up to 14 dollars and more.
 
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