actual neck diameters and reamer prints???

C

crappie

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Im hoping one of you gunsmiths can answer some tech questions. Im trying to figure about actual finished neck diameters and reamers. I have been looking at a few prints for necks at .250" and noted on the print it says tolerance for this dimension is +.0004 on one of pacifics prints. So my question is will this reamer, ream a neck that is .250 + up to .0004 larger plus say .0001 or 2 slop because of the bushing? Or will it definitely be .2504 plus any slop?
Im really after a .251 neck for 222 lapua brass in a savage prefit barrel, haven decided yet whether to get a custom reamer or neck turn.
 
The only thing you can do is decide what neck diameter you want and hope your reamer will cut it exactly. I have 6PPC reamers from 4 major grinders and none of them will cut a chamber neck to within +/- 0.0001" of what I specified. Hitting to the exact tenth requires some luck as well as the grinders skill and measuring equipment. On a new reamer I always hope the reamer will be on the large size by a tenth or so then I can hone it down.

Probably most folks doing chambering do not bother to check a new reamers results. I do. On the first couple of chambers I spend a lot of time with 3 different designs of small hole gages to see if adjustment is needed.

All that being said, at different times I shoot 3 different sizes of necks. Some lots of brass I will make to have 0.0015" clearance, some 0.002" and some 0.003" clearance. Why? I'm still trying to see which is really best overall, and if a particular condition likes a certain clearance.
 
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Nothing to it, unless you want to use the full length of the straight breech end of your barrel it’s all quite simple, really. Buy the reamer, chuck up your barrel blank, dial it in, and cut the chamber as you would normally do except plan to stop at just past the shoulder. This will give you a full throat, neck and the shoulder. Lop it off, clean it up, plug the bore and make a cast of it. Now you can measure the neck, the throat diameter and have a bump and depth gauge to boot.
Individual results may vary,
Nic
 
Crappie,...opinions... methods are varied.....depends on how you wanna resize....my take on a savage...222 ..would be to spec. a std.SAAMI chamber reamer.... then to obtain consistant neck tension and concentricity...a real lite neck turn.
Now if you wanna compete with a .222 in benchrest you`re talking a different ballgame....
OMHO.... worth just what you paid for it.....
bill larson
 
Thanks all. I have measured a few chamber necks with my mitutoyo holtest mics/intrimik but never a custom neck to see how close they cut to spec.
 
JerrySharrett said:
The only thing you can do is decide what neck diameter you want and hope your reamer will cut it exactly. I have 6PPC reamers from 4 major grinders and none of them will cut a chamber neck to within +/- 0.0001" of what I specified. Hitting to the exact tenth requires some luck as well as the grinders skill and measuring equipment. On a new reamer I always hope the reamer will be on the large size by a tenth or so then I can hone it down.

Probably most folks doing chambering do not bother to check a new reamers results. I do. On the first couple of chambers I send a lot of time with 3 different designs of small hole gages to see if adjustment is needed.

All that being said, at different times I shoot 3 different sizes of necks. Some lots of brass I will make to have 0.0015" clearance, some 0.002" and some 0.003" clearance. Why? I'm still trying to see which is really best overall, and if a particular condition likes a certain clearance.
Click to expand...

Jerry,
Can you measure in .0000 increments with a small hole gauge?
 
gauges

chino69 said:
Jerry,
Can you measure in .0000 increments with a small hole gauge?
Click to expand...

my holtests/intrimiks measure in .0002 and ive seen some that do .0001 but its hard to find any that go down to .250, i think most start at .275. I also have another small hole dial bore gauge that measures at .250 and the range is only .007-8 but the grads are .0001. so there are tools out there.

what do you use jerry?
 
chino69 said:
Jerry,
Can you measure in .0000 increments with a small hole gauge?
Click to expand...

Measure in 0.0000", no, but I can most times measure to +/-0.0001", depending. You have to figure part of bore diameter measuring is surface finish Dependant. That is why these old cantankerous tool makers, like Ferris Pindell was and Mike Swartz is (sorry Mike), insist on making gage pins to measure small diameter bores instead of hole gages. I'm not that gifted nor am I that particular!!!
 
crappie said:
my holtests/intrimiks measure in .0002 and ive seen some that do .0001 but its hard to find any that go down to .250, i think most start at .275. I also have another small hole dial bore gauge that measures at .250 and the range is only .007-8 but the grads are .0001. so there are tools out there.

what do you use jerry?
Click to expand...

Something like Starrett #829, 830 and 831.




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