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Page AR-15 » Troubleshooting
AR Sponsor: bravocompany
Posted: 4/29/2016 1:44:26 PM EDT
I think it's time to get some numbered bits for sizing.   I'll never use them as intended (drilling), is there an alternative?   High quality gauges that can accurately measure small thicknesses?  They have to be kinda long, so I don't know if feeler guages will be narrow enough and / or long enough.  

Recommendations?  If bits are the way to go, I'll do it.   Lot of the cheaper sets are junk though.
Link Posted: 4/29/2016 2:59:34 PM EDT
[#1]
Quoted:
I think it's time to get some numbered bits for sizing.   I'll never use them as intended (drilling), is there an alternative?   High quality gauges that can accurately measure small thicknesses?  They have to be kinda long, so I don't know if feeler guages will be narrow enough and / or long enough.  

Recommendations?  If bits are the way to go, I'll do it.   Lot of the cheaper sets are junk though.
View Quote

What kind of accuracy are you aiming for, +/-.002" or +/-.0002"?

Drills can be used as GO-NOGO gauges to a certain degree, for example in a #47 drill goes in, and a #46 drill does not, you know the hole is bigger than .0785" but smaller than .081", you have a range of .0025"
Link Posted: 4/29/2016 6:11:27 PM EDT
[#2]
Mainly for timing the bolt with a lightning link and registered receiver.   On the smaller end.
Link Posted: 4/29/2016 6:28:15 PM EDT
[#3]
Gage pin set.
Link Posted: 4/29/2016 7:09:51 PM EDT
[#4]
If you're trying to measure to accurately determine size, you'll need a very finely graduated set of precision pin gauges.  That is not what you'll be doing when measuring the timing for your link.

If (as for your application) you're just trying to determine a fairly small range with reasonable accuracy, then drill bits will work fine - more than fine.  Use calipers to determine actual shank size for each, as it can vary somewhat from the listed size depending on the quality of the drill bit set - that gets you an accurate range, regardless of the accuracy of the shank size.
Link Posted: 4/29/2016 8:53:06 PM EDT
[#5]
OP, Dano523 posted up a spec on hammer release a while back: #45 drill bit between bolt carrier and barrel extension - no hammer fall; #43 - hammer fall. You might want to confirm with him, but it sounded like an inexpensive numbered drill set would be good enough to get you running.
Link Posted: 4/29/2016 9:45:28 PM EDT
[#6]
Can someone give me a "for dummies" rundown of what you are doing with drill bits in here?

I have built 7 ARs and have never heard of this.

I am not criticizing at all, just genuinely curious about what you guys are doing here.
Link Posted: 4/29/2016 9:47:49 PM EDT
[#7]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Can someone give me a "for dummies" rundown of what you are doing with drill bits in here?

I have built 7 ARs and have never heard of this.

I am not criticizing at all, just genuinely curious about what you guys are doing here.
View Quote

It's for full auto timing - semis need not apply.

ETA specifically, measuring (so as to be able to shim or otherwise adjust) the bolt carrier gap at the point of sear release.
Link Posted: 4/30/2016 3:48:38 AM EDT
[#8]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
OP, Dano523 posted up a spec on hammer release a while back: #45 drill bit between bolt carrier and barrel extension - no hammer fall; #43 - hammer fall. You might want to confirm with him, but it sounded like an inexpensive numbered drill set would be good enough to get you running.
View Quote


Thanks.  This is the only purpose I'll need it for.  I'll look for a set that contains that range.
Link Posted: 4/30/2016 2:20:31 PM EDT
[#9]
Page AR-15 » Troubleshooting
AR Sponsor: bravocompany
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