WECSOG: Wax-Pellet Headspace Test

[W.E.G.]

(This test will allow you to obtain a reasonable estimate of headspace of your receiver/barrel combo by merely tightening the barrel to "hand-tight" - i.e. not fully indexed)

"The WECSOG Wax-Pellet Headspace Test"

1. Hand-tighten the barrel to wherever it stops.

2. Calculate as best you can, how many degrees off TDC you are. You said 10:30, so thats about 45 degrees. If you are exactly 45 degrees off TDC, then tightening-down the barrel to TDC will take up 0.007812" slack in the headspace. Explanation follows.

3. Multiply the number of degrees short of TDC you are by a constant of 0.00017 inches. Make a note of that number, as it is the the value you will subtract from the hand-tight headspace measurement measurement to be obtained in Step 13.
(In case anybody is checking my math...Uncle Buck?..., here goes:
The thread pitch of the barrel is 16 TPI.
There are 360 degrees in a revolution.
One revolution of the barrel changes headspace 0.0625 inches.
0.0625 inches divided by 360 degrees equals 0.0001736 inches change in headspace per degree of barrel rotation.
Sombody slap me if I got this wrong.)

4. Insert a pin gage of reasonable dimension in the locking shoulder recess. I suggest something in the range of 0.258" to 0.262".

5. Insert a "go" gage (1.630") in the clean chamber of the hand-tight barrel.

6. Obtain a ball of stiff wax about the size of a BB, perhaps a bit larger. The idea is that you are going to mash it into a wafer between the boltface and the headspace gage. You don't want it oozing out beyond the boltface. But neither do you want just a mere fleck.

7. Coat the ass-end of the headspace gage, and the face of the <u>stripped</u> bolt with some sort of release agent...like oil.

8. Slide your stripped bolt/carrier assembly into the receiver rails, and push it forward to the vicinity of the breech face.

9. Using three hands or however many toes, place the wax ball between the face of the bolt and the ass-end of the headspace gage.

10. Gently push the bolt/carrier assembly forward so as to compress the wax ball between the gage and the bolt face, and allowing the carrier to move into the full-forward position. The bolt should drop "into battery" during this operation.

11. Gently retract the bolt/carrier assembly, and retrieve the compressed wax ball.

12. Measure the thickness of the wax ball. (Yes, I know wax is elastic, and this measurement will not be an absolute measurement of the space between the gage and the bolt. But, its close enough for WECSOG.)

13. Now, calculate the sum of 1.630 and the thickness of the compressed wax ball. Hopefully the number will be something close to 1.640"

14. Next, subtract the value you obtained in Step 2 from the value obtained in Step 13. Voila! This number is what your headspace would be if you could tighten-down that perfectly good barrel on that P.O.S.-Hesse receiver.

Everybody agree?

[kotengu]

Wow - you have waaaaaaaaaay too much time on your hands Gary! Good explanation, though -

[flashx]

Good one Gary!! Instead of wax you could use Playdough it works great when checking clearances in car engines(piston to valve clearance in a race engine) and may already be in the house if you have kids

[av8tor]

"plastic gauge" would seem to be ideal also
comes in various sizes, available at any auto parts, and wouldnt require a caliper or depth gauge to measure, a "width" reference scale comes on the package

Av

[ September 09, 2001: Message edited by: av8tor ]

[Flipper]

I am new here and have to agree with Flashx, we use playdough on several different gun parts to check things. It is a easy cleanup and there isn't that much elasticity to it, some but not that much.

Flipper

[olephart]

I guess you are assuming that you have something that can measure a ball of wax to .000 with out mashing it, but you don't have something that would measure depth on steel parts to the same accuracy. Otherwise you could just take depth measurements from the actual gun parts and do the math.

The overall proceedure would work, I guess except for #2. Just because you press the front end in .007 does not mean the back end pokes out .007. Most bolt guns close the headspace distance .002-.003 max when the barrel is tightened through 30-45 degrees. I haven't mesured it on a FAL yet, but see no reason for it to be any different - well, maybe if you use 200+ torque and really crush the face of the receiver, you may get more. Ya gotta remember that you are starting with 2 pieces of steel that are in contact and not subject to further movement without some deformity.

Some of the movement is "absorbed" by thread stretch and metal deformity on the barrel that does not promote any closure in headspace. I'll try to remember to measure it next time.

[rwwje]

You should use "Plastigage" from the auto parts store, not wax.:rolleyes: