M14 / M1A / M305 Gas System Accurization & Durability / Self Cleaning Modifications
Before I begin, let me state that I've learned a tremendous amount from this community and its members - if I've learned anything it's how much I still don't know about firearms and marksmanship - and I'm continuing to learn as much as I can. I'd like to give back to the community, and this is my first effort to do so, so if you have any feedback, corrections, or other contributions please don't hesitate to submit them here.
Gas System Accuracy Modifications
Many threads on this forum have been dedicated to accurizing the M14 platform; while the gas system is often mentioned (by way of unitization and shimming of the gas lock), the significance of the gas system on the accuracy of the rifle still doesn't seem to be widely understood. Somewhat counter intuitively, disabling the gas system on these rifles by way of the spindle valve tends to have a negative effect on accuracy, making it difficult to isolate gas system issues.
What seems more common knowledge south of our border, and much less so in Canada, is that the simple act of switching out gas pistons has been proven to reduce group sizes considerably (from 4 - 5 inches at 100 yards to under 2 inches in many rifles with all other variables kept consistent).
The type of piston seems unrelated to the effect on accuracy: while a premium piston such as a Sadlak typically typically offers some improvement in most rifles, in some rifles a well worn piston provided better results.
With most of us owning a Chinese variant of this platform we're unable to interchange gas pistons easily with aftermarket offerings due to the variance in geometry between American gas cylinders and pistons and their Chinese counterparts, leaving us with either the option of replacing the entire gas system with the exception of the gas lock (which needs to remain on a Chinese barrel due to difference in the threading) or switching out Chinese pistons until a good match for the rifle is found.
I would like to propose gas piston exchanges, where several members from the same area get together to swap pistons in an attempt to improve the accuracy of all rifles present. I'm not sure if Barney does this at his clinics as I have yet to attend one (we've met, though), but that certainly would be an excellent place to start if that's not currently the case.
Durability / Self Cleaning Modification
Once a good piston is found for a rifle, keeping that piston and cylinder combination in top condition should be the next priority.
Though the M14 gas system was designed as self cleaning, those of us who have fired more than a box or two of rounds through our rifles know that's not exactly the case: carbon and silica deposits still accumulate on the piston and the tube, and will eventually cause significant wear on both parts. This is largely due to the gas system's self cleaning action only functioning in one direction of the piston's stroke.
There exists a remarkably simple modification that can be made to the gas system tube which allows the piston to self clean in both directions of the piston's stroke, effectively eliminating gas piston wear - member T44E4 on m14br.com details the modification below:
The details of the modification follow:
If a vendor on this forum would adapt the measurements given to Chinese gas systems and start offering this service for a reasonable cost it would be of great benefit to anyone with an accurate M14 pattern rifle.
Before I begin, let me state that I've learned a tremendous amount from this community and its members - if I've learned anything it's how much I still don't know about firearms and marksmanship - and I'm continuing to learn as much as I can. I'd like to give back to the community, and this is my first effort to do so, so if you have any feedback, corrections, or other contributions please don't hesitate to submit them here.
Gas System Accuracy Modifications
Many threads on this forum have been dedicated to accurizing the M14 platform; while the gas system is often mentioned (by way of unitization and shimming of the gas lock), the significance of the gas system on the accuracy of the rifle still doesn't seem to be widely understood. Somewhat counter intuitively, disabling the gas system on these rifles by way of the spindle valve tends to have a negative effect on accuracy, making it difficult to isolate gas system issues.
What seems more common knowledge south of our border, and much less so in Canada, is that the simple act of switching out gas pistons has been proven to reduce group sizes considerably (from 4 - 5 inches at 100 yards to under 2 inches in many rifles with all other variables kept consistent).
The type of piston seems unrelated to the effect on accuracy: while a premium piston such as a Sadlak typically typically offers some improvement in most rifles, in some rifles a well worn piston provided better results.
With most of us owning a Chinese variant of this platform we're unable to interchange gas pistons easily with aftermarket offerings due to the variance in geometry between American gas cylinders and pistons and their Chinese counterparts, leaving us with either the option of replacing the entire gas system with the exception of the gas lock (which needs to remain on a Chinese barrel due to difference in the threading) or switching out Chinese pistons until a good match for the rifle is found.
I would like to propose gas piston exchanges, where several members from the same area get together to swap pistons in an attempt to improve the accuracy of all rifles present. I'm not sure if Barney does this at his clinics as I have yet to attend one (we've met, though), but that certainly would be an excellent place to start if that's not currently the case.
Durability / Self Cleaning Modification
Once a good piston is found for a rifle, keeping that piston and cylinder combination in top condition should be the next priority.
Though the M14 gas system was designed as self cleaning, those of us who have fired more than a box or two of rounds through our rifles know that's not exactly the case: carbon and silica deposits still accumulate on the piston and the tube, and will eventually cause significant wear on both parts. This is largely due to the gas system's self cleaning action only functioning in one direction of the piston's stroke.
There exists a remarkably simple modification that can be made to the gas system tube which allows the piston to self clean in both directions of the piston's stroke, effectively eliminating gas piston wear - member T44E4 on m14br.com details the modification below:
http://www.m14br.com/showthread.php?14474-Added-a-third
It is a .0625" hole at 6 o'clock in the trepan groove.
The purpose of the hole is to allow the silica deposits from the blow-by gasses to be vented, thus preventing a buildup of said deposits. The piston acts as an air pump to force out the residue.
Those deposits will ruin any coating on a piston by attacking the substrate.
If you look at any piston that has at least a hundred rounds on it, you will see the scoring, it is right at the end of the large diameter at 6 o'clock (at the back). The scoring gets worse as the buildup increases and can cause permanent damage to both piston and cylinder.
The details of the modification follow:
If a vendor on this forum would adapt the measurements given to Chinese gas systems and start offering this service for a reasonable cost it would be of great benefit to anyone with an accurate M14 pattern rifle.
