Machinning a LW .25 cal barrel blank questions…..
Guys I just received my blank barrel from LW and would like to start cutting metal as soon as I resolve some issues with it.
First: I meassured my .22 cal factory barrel’s OD at the the end where the breach slides over the barrel. The OD is 0.309″ which gives me a wall thickness of about 0.0445″. If I machine the .25 cal barrel to that aproximate OD I will end up with a wall thickness of about 0.0295″, Is that enough wall thickness for the barrel? or do I need to machine it at a larger OD? Off course, the idea is to have interchangeble barrels.
Second: Is there a good (and simple) way to keep the ID of the barrel centered while machining?
Third: What type of crown do you guys recomend? 11° crown?; Recessed crown?; etc.
Any tips would be greatly appreciated ❗ ❗ 😀 😀
Thanks for all the help 😛 😛
All Replies
Or get one of these puppy’s.
Just make diferant cal’ mandrels and it takes less than a minute to get a perfect 11deg’ crown.
r.h. twist
Shadoh,
Nope – and its hard to tell by looking at them which end is which – I called to confirm after pushing a pellet down. Cant remember how you tell, but one end is stamped with the cal so a phonecall will solve it.
LOL, to slow Wok, he just said that 10 mins before you ). But thanks guys, that makes sense.
Even the LW barrels that already have a choke? I would have thought those are crowned already?
To center the bore of a barrel USE A 4 JAW CHUCK and indicator.
Problem solved.
Thanks Mark!!!!!
Shadoh: If you plan to purchase a “Blank” barrel, you’re going to need to crown it.
This is what I found in another forum:
“In the meantime, I want to share a technique which might help withwork of this nature. I made this brass tool to help center the bore of a badly made MkII Ruger that I wanted to thread for a CAC22. It is very easy to center the OD of a barrel in a lathe, but what do you do when the bore itself is grossly runout? When I indicated the OD of the Ruger bbl to zero, I could see the bore wobbling badly. The bore’s runout was probably > 0.025″. It was gross.
You cannot apply an indicator stem inside a rifled bore, so I turned this brass tool with precision. It has a long .22 cal stem which is a wringing fit into a .22 bore. The OD of the tool is concentric with the stem, thus if I indicate the OD of the tool, I can center the bore.”
Found the pic!!!
Thanks Mark. Eventually Im going to get a .25 barrel that I will need to cut down. I dont think I will need to mess with the crown end at all but that was a question thats been in the back of my mind.
Shadoh
Yes you are right. The bore may not be concentric to the OD.
I cut a recessed, flat crown, to solve this problem.
In my thinking, a flat crown is less sensitive to being out of round.??
I am no expert on crowning, so i didnt address that part of the question.
After cutting the flat crown, I clean up the burr by turning the barrel in the lathe and using an abrasive rubber, dremmel bit. I run the dremmel by hand. I run the lathe forward for half of the time and in reverse half of the time while useing the dremmel tool.
Again, I am no expert at this, but I get reasonabe accuracy. Is there a better way?
Mark
Ok, here is another question. I understand why you put it between centers and not clamp it down with your chuck. The bore of the barrel may not be concentric to the outside of the barrel. Knowing that, how do you put a good crown on when you are done? If you use the chuck wont the crown be off?
Picudo
I can tell you what NOT to do:
1 Do not take heavy cuts, use a SHARP cutting tool
2 Do not let heat build up, the barrel may warp.
3 Do not hold the barrel tightly between centers
If it is held tightly between centers and it warms up and expands
it WILL WARP and BEND.
I put the barrel between centers, with the tail stock LIGHTLY clamped down. If the barrel expands due to heat, it just pushes the tailstock down the ways.
The biggest problem with long thin barrels is chatter – lack of rigidity in the center of the barrel. The follow rest helps with this, if you are turning down the whole barrel.
After putting a center into the barrel, you must crown to clean up the damage from the center.
I Cool the barrel, by dripping water on it. Do not let heat build up! This is very important! Again —> Do not let heat build up, I ruined one barrel that way.
If you are just doing one end, chuck up the the barrel, if it will go through your headstock hole, use the center on the other end, and you will not need the follow rest.
Yes, cutting a .25 barrel to .312 leaves enough wall thickness.
I have done .several 25 barrels that way, as have many others here.
Also, there are two ends to your barrel. You gotta get the right end to cut down. LW marked the ends on the barrels i got (it was in german! ). Push a pellet down the bore and feel for the extra resistance of the choked end. Even if the barrel has no choke, there is still a muzzel end and a breach end, it has something to do with the direction they pull the cutters through the barrel when they cut the rifleing (one way the pellet goes with the roughness generated by rifling and the other way is against the roughness.)
leave your last cut .001 or .002 large, you will loose this when you polish out the cutting marks.
Watch out for taper on your cut, measure in several places along the length of the cut, for the last few cuts. I have a lathe with square ways, and it will cut tapered if I dont watch out.
Congradulations on your new barrel, your gonna love .25!!!
Hope this helps,
Mark
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If its RH one end.. its RH the other end too.