Clarification Wanted: Norc/Poly Front Ferrule Space

Aniest

Aniest

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From Post: http://www.canadiangunnutz.com/forum/showthread.php?t=475587

M14Doctor said:
great point :D

one thing i am noticing on the new chinese plastic stocks is that there is no gap between the gas band and the nose of the stock ferrule. This causes massive pressure against the barrel during recoil and as your barrel heats up..... POI will start to wander all over the place. the gap should be optimally 15 thou.
to resolve this , gently pry the stock ferrule from the tip of your stock. Use a file and remove 15 to 20 thou from the plastic at the U shaped nose and you will also need to relieve the stock itself where it meets the ferrule. a small dremel stone bit is used to gently enlarge the pockets that the ferrule crimps engage.
install the ferrule and check the gap.... do you see daylight...... good..... now apply epoxy paste and re install the ferrule, keeping it's face, 90 degrees to the stocks top plane. use a small punch to gently tap the ferrule crimps back down, wipe away any excess epoxy paste and recheck the ferrule is 90 degrees to the top plane and allow to set till the next day.
This alone, is a good thing to check as if present in your rifle, you are NOT going to see any improvements in accuracy , regardless of other mods, no matter how free or expensive they are.
Click to expand...

I have been pretty good at understanding the explainations on doing M14 tweeks and such, but this one has got me stumped.

:confused: Where exactly is the 15 to 20 thou gap supposed to be? :confused:

On the following pictures which one of the four areas is this gap supposed to be. In other words, if the red line is a 15 to 20 thou gap, which one should it be?

First photo: side close-up, forearm of stock, no handguard, "8" shaped band and gas assembly.
Norc%20M14%20Gas1.jpg


Second Photo: side close up, forearm of stock, no handguard, "8" shaped band removed and gas assembly slightly pulled out.
Norc%20M14%20Gas2.jpg


Right now I have a gap at 2. No gap at all at 1,3 or 4.

Thanks in advance....

Aniest
 
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carbonrod said:
There should be a gap at 1, 2 and 4. 4 should be large. 3 should produce some down pressure.
Click to expand...

Thanks for that info.

I was "Guessing" it would be a gap at #1 and #4, with contact at #2 & #3 to allow the stock to not shift around a lot. Then the gap at #1 to would allow heat expansion, and the gap at #4 would not allow possible pressure between the stock and gas assembly.

Guessed wrong! :eek:

What do you mean by "3 should produce some down pressure." Pressure down to what direction? Down pressure that would/could cause the gap at #2 to be smaller if the pressure continued?

This one clarification is like Starboard and Port on a ship... sometimes right and left, up and down are relative to where you look and what terms you use. To me all positions are based on being the shooter (at the stern of the ship) looking forward to the muzzle (bow) . :p
 
the only contact point between the rifle and the stock at the ferrule location is on the bottom, where the tab of the gas band engages under the stocks ferrule.

When I NM condition a stock ferrule, I remove it and reseat it for 15 thou between the front face and the gas band and so it sits absolutely flush with the top plane of the forestock.
then once it has set, I ream out the "U" shape of the ferrule and stock with a dremel to clearance the gas assembly all around.

as i said , the ONLY contact point for the stock ferrule , by design, is the portion that contacts the gas band engagement lip and no where else.
 
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Thanks for the descriptions... now I understand what is going on: basically trying to "free float" the entire ferrule from the gas system and barrel, NOT including what I call #3 in the first picture, it should be tight and applying pressure down onto the gas band.
 
That is the thinking in match conditioning these.

But to be honest, I would just go and shoot it if I were you. Some accuracy improvements have a big improvement on some rifles, some not so much. If you start shooting it, and find that it does not meet what you want, you can do all the mods, or have a guy like M14doc above do them.

Often, you are taking a rifle that is a 3MOA rifle out of the box, and making it a rifle that is 1-2MOA though.
 
Definitely an extreme step in "match conditioning". Unless you have woeful accuracy, I wouldn't loose too much sleep over how the ferrule sits. These are battle rifles, designed to hit man sized targets within visual range.
 
The Kurgan said:
Definitely an extreme step in "match conditioning". Unless you have woeful accuracy, I wouldn't loose too much sleep over how the ferrule sits. These are battle rifles, designed to hit man sized targets within visual range.
Click to expand...

an extreme step?
actually it is probably one of the simplest and easiest "corrections" a person can perform at home. The rifle is not designed to have ferrule contact other than stated above. It is not a match conditioning step to correct how the ferrule sits. MOST norinco wood stock, usgi wood stocks and usgi fiberglass stocks have correct ferrule gap and in correct position and probably can skip this entire thread if you have one on your rifle ;) BUT if you have one of them new chinese plastic stocks that came on the last big import......your rifle will beneffit from reading this thread.
reaming out the U shape to further gap the barrel IS a match conditioning step, but it is a little more than 3 minutes with a dremel and maybe 5 or 6 minutes with a good 3/8" rat tail file. Generally i tell folks this is an extra step and not essential to perform.

but the 15 thou optimal gap between the end of your stock and the gas band is important to the accuracy of your rifle.... especially after the barrel starts to heat up
 
Grouping told me I needed it...

M14Doctor said:
especially after the barrel starts to heat up
Click to expand...

:D That's the Known concern for me!! :D

I have a 2009 Poly that once I scrubbed it clean and did a lot of the mods suggested by Hungary, M14 Doctor and those fine peoples I found one problem: More shots meant more barrel heat, and that meant worse groups!

The first thing I thought of was the ferrule stressing the gas assembly... so here I am trying to understand how to fix it. I figured if I didn't quite get it than someone else could use the pics to understand it too! :cool:
 
the plastic poly stocks are a bit of a bugger to get the ferrule off. essentially a small flat blade instrument and yes, pry her off. may require some fine tuning with pliers to straighten any kinks out that may form during removal.

then with a file, carefully remove material from the forstock from both the ferrule lip face, the part it goes on, and the main body of the stock. This is to allow for the ferrule to be seated farther back on the stock.

once the modifications are done, put the ferrule back on without epoxy and assemble to rifle, observing the VERTICAL gap between the front 90 degree face of the ferrule and the gas assembly band.

if you want to be technical and by the book... this vertical gap should be 15thou optimally but for the layman...... as long as you see light through it and have at least a milimeter of space between the vertical face of the ferrule and the gas band.... yer good to go. use a reliable 2 part epoxy paste and reseat the ferrule, ensuring the face is 90 degrees to the top plain of the stock.

those with fiberglass and wood stocks (chinese ones included) most likely can skip this whole thread as the problem we are discussing primarily affects the plastic stocks..... every single one i've seen as a matter of fact. We are talking about fixing a problem that is inherent to the plastic stocks, this ferrule "re seating" is not an NM modification.... it is a correction.

now..... as for actual NM modifiations of the stock and ferrule....... this is a DIFFERENT procedure and applies to all stocks and pertains to clearancing the ferrule around the gas cylinder to relieve any contact points between stock and action. This can be done with a rat tail file or careful application of a dremmel with a cylindrical grinding stone. Essentially, looking at the nose end of the stock with ferrule in place.... it appears as a "U" shape...... and you want to make it look more like a circle with the top missing ;) . So, remove only enough material from the side wals and bottom of the "U" of the ferrule until you see a visible gap all around the cylinder.

Now the only part of the stock that should be in contact with the gas cylinder is the bottom outside of the ferrule, where it engages the lip on the gas band..... a location where NO MODIFICATIONS should take place.
 
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carbonrod said:
That is the thinking in match conditioning these.

But to be honest, I would just go and shoot it if I were you. Some accuracy improvements have a big improvement on some rifles, some not so much. If you start shooting it, and find that it does not meet what you want, you can do all the mods, or have a guy like M14doc above do them.

Often, you are taking a rifle that is a 3MOA rifle out of the box, and making it a rifle that is 1-2MOA though.
Click to expand...

Exactly what M14Doctor recommends is great advice. Carbonrod has it right... go out and shoot it lots. Group it and have fun. Worry about accurizing if it really and truly needs it. That issue about the gap(s) is not as important as say ' handloading match bullets' for accuracy. There are other cheaper and more important tweaks. :)

Cheers and Merry Chrismukkah!

Barney :agree:
 
Hey, I got my polytech ferrule off and modified as recommended. I used JB weld to put er back on. I was worried that it was epoxied on in the first place - but it was just a press fit so I got it off without destroying it. I then took a ruler and drew a line 2mm around the ferrule flange and stock - used an angle grinder to do the majority of grinding and then a file to finish it off.

I find I have quite a lot of variability between a hot barrel group and a cold one (-20C here) so hopefully this helps. If I see a coyote I'd like to be able to shoot it with my barrel cold ;-).
 
Can we sticky this thread for all the plastic stock users?

M14Doctor said:
the plastic poly stocks are a bit of a bugger to get the ferrule off. essentially a small flat blade instrument and yes, pry her off. may require some fine tuning with pliers to straighten any kinks out that may form during removal.

then with a file, carefully remove material from the forstock from both the ferrule lip face, the part it goes on, and the main body of the stock. This is to allow for the ferrule to be seated farther back on the stock.

once the modifications are done, put the ferrule back on without epoxy and assemble to rifle, observing the VERTICAL gap between the front 90 degree face of the ferrule and the gas assembly band.

if you want to be technical and by the book... this vertical gap should be 15thou optimally but for the layman...... as long as you see light through it and have at least a milimeter of space between the vertical face of the ferrule and the gas band.... yer good to go. use a reliable 2 part epoxy paste and reseat the ferrule, ensuring the face is 90 degrees to the top plain of the stock.

those with fiberglass and wood stocks (chinese ones included) most likely can skip this whole thread as the problem we are discussing primarily affects the plastic stocks..... every single one i've seen as a matter of fact. We are talking about fixing a problem that is inherent to the plastic stocks, this ferrule "re seating" is not an NM modification.... it is a correction.

now..... as for actual NM modifiations of the stock and ferrule....... this is a DIFFERENT procedure and applies to all stocks and pertains to clearancing the ferrule around the gas cylinder to relieve any contact points between stock and action. This can be done with a rat tail file or careful application of a dremmel with a cylindrical grinding stone. Essentially, looking at the nose end of the stock with ferrule in place.... it appears as a "U" shape...... and you want to make it look more like a circle with the top missing ;) . So, remove only enough material from the side wals and bottom of the "U" of the ferrule until you see a visible gap all around the cylinder.

Now the only part of the stock that should be in contact with the gas cylinder is the bottom outside of the ferrule, where it engages the lip on the gas band..... a location where NO MODIFICATIONS should take place.
Click to expand...
 
If I recall, I had posted pics at one point of how to correct the Norinco plastic stock ferrule spacing. No idea where that thread is now, it should have been stickied I guess?
 
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