View Full Version : Pin Gauge
07-07-2012, 09:34 PM
I have a Kotonics barrel I need to see if it's in spec. Could someone please provide me some information on where I can get a pin gauge to drop through my barrel? Company name, and size of gauge would be greatly appreciated.
07-07-2012, 09:43 PM
PM owenslee i know he knows where. There is a thread in here some where pertaining your concern. Did you also try a search.
07-07-2012, 09:54 PM
Thank you WASSMAN, I did indeed use the search feature with no success. If you have any suggestions on search parameters, I would greatly appreciate it.
07-07-2012, 10:01 PM
Here this might help. See owenslee posts. http://68forums.com/forums/showthread.php?29772-FS-18-quot-Kotinics-Barrel-and-Bolt&highlight=drop+test
07-08-2012, 12:33 AM
I would suggest initially buying two gauges to inspect your barrel:
One english unit .2700" Plus gauge ( should be marked: .2700ZP) This will have a nominal dimension of. .2700" -.0000 +.0002 tolerance
The second english gage should be a .2700" Minus gauge ( should be marked: .2700ZM and will have a nominal dimension of .2700" -.0002 +.0000 tolerance.
First... leave the barrel and pins at room temperature (70 deg) for a minimum of several hours to stabilize. Use brown Jersey gloves to handle the gauge pins to avoid your fingers warming the pin.
Make SURE you do NOT have a burr at the gas port in the bore...by brushing the bore several times with a nylon or bronze bore cleaning brush. If the barrel has already been fired, this step is not needed as any burr that was originally present will be gone.
Be sure the bore and gauges are clean and dry. Do NOT lubricate either bore or pins.
Use the .2700ZP gauge and carefully place in the muzzle with the chamber end down sitting on top of a shop towel. If the gauges passes unrestricted completely through the bore of it's own weight and drops out the chamber... your barrel's minor bore diameter is above minimum tolerance and is fine. If the gauge is a snug fit... but still passes easily with LIGHT pressure applied against it using a coated / brass / aluminum cleaning rod... you are still good to go. If you feel resistance...STOP. If resistance is ONLY felt in the area of the gas port, you may still have an unremoved burr.
If the .2700ZP gauge will not pass through the bore with LIGHT pressure, then remove the gauge using a coated cleaning rod applied from the chamber until the gauges slips out of the bore. Then substitute the .2700ZM gauge from the muzzle and repeat the test. If the .2700ZM gauge passes easily through the bore of it's own weight or with light pressure... the barrel is up to .0002" undersize...but still safe to shoot. (I have safely shot a barrel that was approximately .0003" undersize. )
If the .2700ZM gauge does NOT pass through the bore with light pressure, then the barrel is more than .0002" undersize and would be considered questionable to shoot without further measurement, requiring the purchase of additional gauges.
The gauges I would suggest are Meyer Gauges and they can be purchased here for only a few dollars each + shipping.
07-08-2012, 06:58 PM
Kerry, Thank you so very much! This is exactly what kind of help and information I was searching for. Your the best!
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