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Posted: 4/27/2015 4:28:26 PM EDT
Hi all, I'm new to the forum but was an armorer in the Army 30 years ago so I'm not new to the AR platform. Does anyone have the drawings or dimensions for go and no-go headspace gauges for 300 BLK? I'd like to make my own and save $70. I posted this already in the Basics Forum but only learned that I don't need to check it. I already know that I probably don't need to but would like to none the less.
Link Posted: 4/27/2015 4:59:46 PM EDT
Go to the SAAMI homepage and look around. I'm sure they have all that listed there.

Greg
Link Posted: 4/27/2015 5:29:30 PM EDT
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Originally Posted By GLShooter:
Go to the SAAMI homepage and look around. I'm sure they have all that listed there.

Greg
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No, just case and chamber dimensions. I asked the same question on the 300 BlkTalk forum but haven't heard anything yet.
Link Posted: 4/27/2015 7:38:08 PM EDT
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Originally Posted By roostonu:

No, just case and chamber dimensions. I asked the same question on the 300 BlkTalk forum but haven't heard anything yet.
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Originally Posted By roostonu:
Originally Posted By GLShooter:
Go to the SAAMI homepage and look around. I'm sure they have all that listed there.

Greg

No, just case and chamber dimensions. I asked the same question on the 300 BlkTalk forum but haven't heard anything yet.



Here you go. Straight from SAAMI's site. I just did a quick search. I've got a new BHW barrel ordered so will be looking at it more in the future just so I can be familiar with it.

http://www.saami.org/pubresources/cc_drawings/Rifle/300%20AAC%20Blackout.pdf

Greg
Link Posted: 4/27/2015 9:36:19 PM EDT
Those are case and chamber dimensions. I need gauge dimensions.
Link Posted: 4/27/2015 11:10:27 PM EDT
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Originally Posted By roostonu:
Those are case and chamber dimensions. I need gauge dimensions.
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From the case dimensions, you should be able to make a set of GO and NOGO gauges.

Here is a comparison of gauges and case for .308:


Link Posted: 4/27/2015 11:18:59 PM EDT
My thoughts exactly.

Greg
Link Posted: 4/28/2015 8:09:16 PM EDT
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Originally Posted By lysanderxiii:

From the case dimensions, you should be able to make a set of GO and NOGO gauges.

Here is a comparison of gauges and case for .308:

http://media10.dropshots.com/photos/493614/20120802/205420.jpg
http://i1052.photobucket.com/albums/s442/f67stang2/b_194151_zpsee88b8a7.jpg
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Originally Posted By lysanderxiii:
Originally Posted By roostonu:
Those are case and chamber dimensions. I need gauge dimensions.

From the case dimensions, you should be able to make a set of GO and NOGO gauges.

Here is a comparison of gauges and case for .308:

http://media10.dropshots.com/photos/493614/20120802/205420.jpg
http://i1052.photobucket.com/albums/s442/f67stang2/b_194151_zpsee88b8a7.jpg


Thanks for the help. The tolerances are much tighter on the gauge than the chamber and cartridge, which I wasn't expecting. I'm back to purchasing them if I must have them. They should be ground instead of turned for the diameter tolerances of +/- .000I with a taper. If there wasn't a taper I could turn them here at work.
Link Posted: 4/28/2015 8:53:16 PM EDT
Headspace gauges are basically "tool and die" parts with really tight tolerances. I got my PT&G 300 Blackout gauges from Midway - they have the NO GO gauge in stock, but the GO gauge is backordered...
Link Posted: 4/28/2015 10:49:10 PM EDT
Even if you had the capability to grind to a ten thousandths, could you make one for less than $40 - $50?

A fun project but I doubt cost effective.
Link Posted: 4/29/2015 9:20:02 PM EDT
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Originally Posted By lysanderxiii:
Even if you had the capability to grind to a ten thousandths, could you make one for less than $40 - $50?

A fun project but I doubt cost effective.
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Free unless you count the time involved.
Link Posted: 4/30/2015 7:25:05 PM EDT
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Originally Posted By roostonu:

Free unless you count the time involved.
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Originally Posted By roostonu:
Originally Posted By lysanderxiii:
Even if you had the capability to grind to a ten thousandths, could you make one for less than $40 - $50?

A fun project but I doubt cost effective.

Free unless you count the time involved.

If you're not used to holding 1/10,000 tolerances, you could be talking about a LOT of time.
Link Posted: 5/1/2015 7:54:00 PM EDT
[Last Edit: 5/8/2015 5:38:13 PM EDT by roostonu]
I'm a dimensional inspector at a 30k Sq ft aerospace machine shop. AS9100 and ISO 9001 certified and FFL licensed manufacture. I can measure just about anything with repeatability of .00004 or 40 millionths/1 micron. If we were set up for grinding, which we're not, I would have a friend do the machine work. We trade my reverse engineering for their machining capabilities. I do a little machining but not that tight.
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