I"m getting ready to finish my 80% lower and have a question about reamer sizes.  I've read through the Ray Vin book and it lists reamer sizes as follows:

Take Down 0.251
Safety 0 .376
Trigger/Hammer 0.156

I've done a little looking around for these reamers, but haven't found any yet.  Does anyone have a source for them and are these the right sizes.

Thanks,
Bob

 

Why do you want to reem vs just drilling w/ the recommended sizes?

Search on eBay.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2055119.m570.l1313.TR2.TRC0.A0.H0.X5%2F32%22+reamer.TRS0&_nkw=5%2F32%22+reamer&_sacat=0

http://www.ebay.com/sch/i.html?_odkw=5%2F32%22+reamer&_from=R40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR2.TRC1.A0.H0.X3%2F8%22+reamer.TRS0&_nkw=3%2F8%22+reamer&_sacat=0

Have you ever used a reamer before?  If not, watch some videos and do some reading.  It's real easy to make an oversize or oblong/otherwise misshapen hole with a sharp reamer.  Otherwise, you'll be better off just using quality drill bits



5/32"

Agreed...............if you know how to use one.

If not, you'll more easily enlarge/deform the holes with a reamer than a twist drill.  Twist drills don't side cut anything like a reamer or end mill; they mostly flex.  I use reamers, but before ATF said no more, I had let some other guys finish 80% lowers with my equipment, including reamers.  More than one of them ended up with an oversize hole.

Therefore I maintain that someone with no machining experience is better off with a quality jobber length twist drill.  Finish won't be as pretty, but an ugly hole of the right size beats a pretty one that is out of spec.  Pins 0.020" too far apart is enough to cause disconnector malfuntions.

Sorry for my typo everyone.  I fixed my post to not confuse anyone later.

https://www.mscdirect.com/browse/tn/Holemaking/Reamers/Chucking-Reamers-Sets/Chucking-Reamers?navid=12106128
Under decimal sizes

Not splitting hairs - but AFAIK, mil spec hole size officially is 0.155.

ENCO sells reamers to that diameter.  But as has been stated - a reamer is different in usage.  You don't peck with it and you advance smoothly and stop once through.  If you mic your trigger pins, you will likely find 0.1545 as the diameter.   I think this discussion should apply to those with a mill.  Regardless a 5/32 should work fine.  Remember the J pin will capture the center of the hammer pin and the hammer springs will keep the trigger pin in place.  If any concerns, get anti-walk pins from KNS.

Holes are reamed to a certain size because of the anodizing process build up inside the hole. The finish should be also be considered when you select the diameter of the hole.