Take a look at item no. 24.

A real gas lock wrench is nice though...
Taken from Tony Ben's Guide "Common tools to maintain and disassemble the M14/M1A"
1. Grease of choice. I prefer Lubriplate 130-A which can be purchased from Brownell’s. Other popular greases are Plastilube, Tetra gun grease, TW-25b and even wheel bearing grease
2. A small artist’s paint brush for application of grease (optional)
3. A Chamber maid flexible bore brush handle (optional). This item is not an absolute necessity but will make cleaning the chamber much easier than using a GI chamber brush and a patch. GG&G also makes their own version.
4. A GI multi-tool (optional)
5. A 3/8” boxed end wrench (optional)
6. A multi-bit handle (optional)
7. A cleaning rod bore-guide. I consider this a necessity to properly protect the barrel crown from damage during cleaning.
8. A chamber cleaning port. I think this one is made by Possum Hollow. You can find them at Sinclair's. (optional)
9. Multiple bits consisting of standard allen sizes and screwdriver tips for use with item number 6. (optional)
10.A cleaning rod section with a 45cal bore brush used to clean the flash suppressor (optional)
11. A gas cylinder/gas lock wrench. (can be substituted with Items 24 and 25) The one shown is a BAD-T4 tool that can be used with GI gas locks and Smith Enterprise gas locks which include dovetails for front sights or gas locks with permanently integrated front sights. Smith Enterprise and Sadlak also sell versions and there are also GI gas lock wrenches available.
12.A BAD-T1 tool (optional). This tool can be used to disassemble the M14 rifle and includes integrated gauges to measure muzzle wear, throat erosion and flash suppressor alignment. It also includes a storage pot for grease and can also be used with multi-bits (allen and screwdriver bits). It also has an adapter to measure throat erosion on M1 Garands. The tool is very expensive but is well worth the money if you are in the habit of measuring and monitoring throat erosion and muzzle wear as well as frequent self-gunsmithing.
13.A #15 long drill bit with handle. This is needed to clean inside the gas piston tail.
14.A letter “O” drill bit. This will be used to clean the inside of the gas plug.
15.A letter “P” drill bit. This will be used to clean the large opening in the gas piston.
16.A GI chamber brush. (Optional with suitable substitute)
17.A .30 caliber bore brush with brass shank.
18.A 45 caliber bore brush used to clean the chamber in place of a GI chamber brush (optional).
19.A 45 caliber bore mop (optional). This will make thorough removal of solvents much easier and quicker.
20. If using an eyelet attachment to clean the bore, use an eyelet with a 30 caliber cotton cleaning patch.
21. If using a cleaning jag, use a jag with a 22 caliber cotton cleaning patch or a 30 caliber cotton cleaning patch cut in half.
22.A nylon cleaning brush.
23.A set of castle nut pliers. The ones shown are home made but others can be purchased on gunbroker or Brownell’s.
24.A large crescent wrench as a substitute for a gas lock wrench (item number 11).
25.A strip of leather for use with item 24.
26.Solvent of choice.
27.Oil of choice.
28.A one piece cleaning rod. It doesn’t have to be an expensive cleaning rod. The expensive ones are nice but I used a $12 coated cleaning rod and it worked fine. When using a jag to clean the barrel instead of an eyelet, it will take more effort to push it through the barrel and you may bend it. The expensive ones won’t bend but as long as you are careful, a cheap one will do fine.
Tony.