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Using barrel centers

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rock_breaker

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#1
I have made brass centers for a 223 that won't go in with out some force. Need advice on what to do next. The pilot for the muzzle end is 0.223 dia and about 0.625 long. It starts into the barrel but gets tight about 0.25" into the barrel and I am sure it will go with some force from the tail stock. The same is true for chamber end only it is 0.377" in diameter and approximately 0.375" long
I intend to drill a 0.1875" hole in the chamber end pilot so that I can force the muzzle pilot out. I believe the chamber end will come out with a slight twisting motion. My Lyman Reloading Handbook says the straight portion of the chamber 0.20 long by 0.376 dia. I am confident the chamber pilot will come out easily once it is cut to 0.20 long.
Out of curiosity I mounted both pilots just snug enough to stay in the barrel then mounted it between centers, got 0.005" run out at the chamber end and failed to measure the muzzle end (lunch break). Will measure the muzzle end when ready to do the threading. With a 7/8 X 14 thread I am not sure what might be an acceptable run out if any. Would sure appreciate the advice of the experienced members of this website.
Have a good day
Ray
 

pontiac428

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#2
Rather than try to do anything with .005 of run out, I'd prefer to use the centers and re-cut the crown after you're done. If you're muzzle threading, you'll probably be doing that anyway. I haven't had very good results with center arbors because they compound eccentricity between the center spot, the arbor body, and the fit in the bore (but that's just me). I lose trust in the fixture system pretty quick if the dial starts hopping. You can also make a ring for the muzzle end to ride in the steady rest if you're trying to save the barrel's finish.
 

rgray

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#3
.223 is bullet size so that won't fit in the bore well. Trying to hit a size that fits snug will be almost impossible and will either be to tight
like you have (better than loose) or to loose and show up as differing readings on the indicator.
Groove diameter in a .223 is .218 usually.
My barrel rods have a taper and the small end is .217 with the larger end .224 over a length of 3.7 inches the rest of my rod is .287 dia for 4" so the rod is approx 8" long. I use one in each end of the barrel when setting it up.
The rods are hardened & ground it would be tricky to cut that taper on a lathe.

They sometimes are hard to remove by hand. I use the tailstock drill chuck and pull the muzzle end out that way. A cleaning rod will knock the other out so easy you'll wonder why you couldn't remove it by hand.

Try to get your runout down into the tenths....like .0002.... Floating chamber reamer....Do the last part by hand (or the entire chamber) the reamer is self piloting.
 
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Lordbeezer

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#4
223. 5.56 bullets are .224..older 22 hornets are 223.
 

Tozguy

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#5
Sounds like the barrel is a used one, is already chambered and bore has wear at the muzzle (from cleaning?).
Be aware that the OD of the barrel might not be concentric with the bore to start with.
Based on the limited information, I would consider using centres directly in the bore and chamber (as mentioned above) and then cut the threads.
Set up a steady rest on the new threads and recut the crown.
For best accuracy, the muzzle should be cut back 1/2 to 1'' to remove the worn rifling.
 

pdentrem

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#6
Remember that the groove diameter is different than the land diameter. I did my barrels on centers as well.
 

rock_breaker

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#7
Thanks guys! Tozguy has hit the data about the barrel pretty well, it is a used barrel with a flat counter sunk muzzle. The OD at the muzzle is 0.880" and the counter sink is about 1/16" deep by approximately 5/8 dia. The chamber end is as I recall 1.125" This project started when the neighbor brought the barrel and about 2 foot X 1.5" dia of "the strongest aluminum he could buy" . He has some machining experience and my impression is that all that was required was to mount it in a 4 jaw chuck and cut the threads. I do think there is cleaning rod wear in the muzzle so it should be cut off but should it be crowned, countersunk or left flat?
The barrel is shorter than the spindle on the Enco 13 X 36 lathe so the use of centers is almost a necessity. I can put a center in the chamber and use a center turned for use inside the left end of the spindle. I found some runout on my first attempt at the "internal center" so another one is required if I use the 4 jaw chuck. Not sure if I have enough room for a sleeve over the threads at the chamber end.
 

Tozguy

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#8
My suggestion is to cut a 90 deg crown with a 45 deg chamfer on the rifling. The chamfer should be shallow, only deep enough to do all the rifling and just take the edge off the bore. Finish the o.d. of the crown as it was before.
Re the steady rest, run it directly on the new threads, no sleeve, it sounds odd but it works!

The alternative to shortening an already short barrel (to remove the worn rifling) is to counterbore if you have the tools.
Note that this makes subsequent cleaning more of a chore since the counterbore accumulates a lot of crud from shooting.
 
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