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Posted: 7/1/2006 11:59:49 AM EDT
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What does this gain one? I'm not sure what one really could look like. My M1A loaded shoots .5 to .75" in groups at 100 yds now with out even trying very hard. Thanks, Bill |
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Bill, The M-14 barrel requires downward tension to make the barrel happy/sing (all the crap hanging off it). Unifying the front band (the tension point to the stock) to the gas cyclinder keeps the tension at a constant, than if the band was to move and change the tension. If your rifle will hold groups, does not have flyers, and POI stays the same through out the stings, then it you will not see any benifits from the mod. |
Here's a unitized gas system put together by M14 gunsmith Ted Brown. It uses the Army "screwed and glued" method: The U. S. Marine Corps used soldering to unitize the M14 gas system. For newbies, there's more involved with unitizing the gas system than "mating" the front band to the gas cylinder. |
You should go to Camp Perry. With match ammo and a little effort, you could put them all in the same hole. |
+1  If he shoots that good with surplus, who needs match ammo? 
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Gee, I'm almost afraid to ask questions as a M14 newb. I'm a dick too and thick skinned, so I'll be able to take it. I have seen the gas system unitized using three tig welds. It seems to me that tig would be more secure than screws. What are the differences between the different unitizing methods? |
Usually it all boils down to the individual gun plumber as to which method they prefer. There is screwed and glued, welded and a mixture. One of the problems now is that most of the true M14 armorers are getting old and getting out of the business. Just about every armorer prefers their own method and says it is the best. One thing is for sure, just about any and all of them can fail. Constant monitoring is needed to keep that from happening, but with time and all the recoil, movement, etc. it can and will happen. |
Very true on what was said above. I personally prefer the USMC method of soldering/welding the front band to the gas cylinder as this does not require a screw through the gas shut off valve. This allows you to still retain the use of the shut off for cleaning, or disabling the gas system if needed. |
Thanks for the input guys! Good call on the screw and glue method. It makes sense not to eliminate the valve. |
warbird and Ted Brown report the following experiences with Springfield Armory, Inc. M1A gas systems. The spindle valve hole in gas cylinder is larger than the USGI drawing dimension. The spindle valve diameter is smaller than the USGI drawing dimension. The departures from USGI drawings are causing undesireable gas bleeding. The spindle valve is too hard to drill with a cobalt bit. If you anneal the spindle valve, it will sometimes crack. The gas cylinder is too hard. Wayne Machine, Inc. (Taipei, Taiwan) makes the gas cylinder for Springfield Armory, Inc. I don't know who makes the spindle valve for them. I have questions too. 
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Here's a good description of what is involved with modifying the M14 type rifle gas system. This is what hueygunner (across the street) does in the "screw and glue" M14 NM modification: 1. Annealing the spindle valve 2. Annealing the front band and tangs and reaming out both holes .020 inch oversize. 3. Drilling and tapping of the spindle valve. 4. Drilling and countersinking of the gas cylinder flat and the front band. 5. Bending the front band upper hand guard tangs up to the correct angle. This is checked with a new hand guard for positive fit. 6. Reparkerizing the front band with original dark black grey mil-spec parkerizing solution. 7. Epoxying the items and screwing together with 6-32 blackened stainless screws which are also staked. 8. Drying of a completed assembly on a brand new SAK NM barrel 9. Checking gas hole alignment 10. Fitting piston to bore. This is done utilizing a brand new TiN coated Sadlak NM gas piston. 11. Complete cleaning out of gas cylinder bore and inspection of all tolerances. 12. Complete Tech Inspection on gas cylinder and prompt notification of any problems found. |
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Downsides of the TiG method: -when it cracks, you're done shooting accurately for the day -there will be some amount of distortion of the gas cyl depending on the skill of the guy doing the work. Not an issue if it's well done. Downside of the glue and screw method: -Screws might shoot loose (probably not going to happen if they're staked in place as the photo above shows). You can tighten the screws if they do. -Spindle valve inoperable (I've never had a use for it anyways) I'd go with whatever the armorer recommends. Some of them have a preference one way or the other, some don't. |
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When unitized, the barrel and gas cylinder holes in the band are enlarged to prevent contact tension. With just shimming alone, the stock is going to pull the band all the way down, and since the band can in fact move, and may be tensioned by the gas cylinder having direct contact with the band, the rifle will take time to settle in the band to the lowest tension point caused by the barrel tension, yet still have slight movement in the band through cylinder r barrel expansion. Furthermore, if you pull the cylinder, you will have to wait again for the band to resettle. Note: Tension when tightening the lock on the shimmed cylinder is the lock hand snug at the 4:00, and wrenched to the 6:00. If you apply more torque than this, then you have middle tensioned the barrel between the lock and the barrel shoulder (read a bad thing, and not enough tension to hold the front cap solid/stationary). |
As Dano said, pinching the band doesn't mean it's not going to move (especially when the stock is pulling downward on it). If you want a rifle that shoots better, then shimming might be a good option. If you need to it shoot consistantly well, then the unitized gas system is the way to go. Ty |
| Shimming is more effective than unitizing. Simple reason is that the cylinder is supported at both ends (shoulder at back and lock up front) instead of just at the front by the lock. You'll get less vibrations through the cylinder. Personally, I have both unitizied and shimmed. If shimmed correctly, the lock stops at about 4:30, then with a bit of muscle on a wrench, it can be set at 6:00. The band wont shift at all. As long as it has been aligned off the barrel without contact, it should have the same effect as unitizing plus, its mor stable. |
I guess... I'm not sure why you'd bother unitizing if you weren't going to fit the gas cyl to the barrel so that it has to be driven on with a mallet and finish the job properly by choosing a gas cyl lock that times appropriately. Ty |
If it's shimmed, you wont need a lock that times where you want, the shim you choose will control where it times. As far as banging the cylinder on, thats about "pinging" the splines on the barrel. That should be done, if needed. |
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