Is it Necessary to cut off material from the chamber end on new blank?

Discussion in 'Advanced Gunsmithing & Engineering' started by GAnderson, Aug 19, 2017.

  1. GAnderson

    GAnderson Silver $$ Contributor

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    Was wondering if it is absolutely necessary to cut off 1/2" or so from the chamber/shank end of a new barrel blank before chambering...you are going to chamber that area anyway, so do you need to cut any off or do you just remove from the muzzle end only? My reason for asking is that I have a blank that is a remington varmint contour and the shank end seems awful short...by the time say 1/2" is removed and then you cut remington thread/tenon, there is only about 3/4" before it starts contouring down. Thanks

    Gene
     
  2. butchlambert

    butchlambert Site $$ Sponsor

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    Gene, remember that the lap starts and stops in the breech end. It is normally slightly larger and maybe not round. I understand that the chamber will cut that out, but will you get a good indication in that area?
    Sounds like a hunting rifle, probably wouldn't matter.
     
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  3. Cloudrepair

    Cloudrepair

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    I'm interested in seeing what these guys have to say.
    They know more about the manufacturing of the barrels.
    I dial in the projected throat with a long reach indicator and drill prebore then double check my dialed in section with a different tenth indicator that has the body that fits in my prebored section then chamber.
    I don't cut any off the breach only the muzzle.
     
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  4. hammerjack

    hammerjack Silver $$ Contributor

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    I would cut around a 1/4 off or less and put up in case you need to send the barrel back.
    Kreiger just replaced a barrel I sent back ; they are stand up people.
     
  5. Cloudrepair

    Cloudrepair

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    I guess what I believe is it doesn't matter as long as you understand what Butch has pointed out and a way to overcome it.
     
  6. GAnderson

    GAnderson Silver $$ Contributor

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    Thanks for the replies guys.
    Butch, yes that was my concern about the lapping "bell" that is created and not getting the chamber started correctly. I think I may have to send this blank back. By the time I have some taken off the breech end and then the threaded tenon for a Remington is done, there just isn't going to be enough of the 1.220 shank diameter left before it starts contouring down...it just isn't going to look right. I have no idea why the shank was cut so short to begin with. What I normally see is at least a 3" length of the shank before it starts into the contour and this barrel for some reason only has roughly a 2" shank. I have been in contact with the barrel manufacturer and they said to send it back. Was just trying to determine any possible way to go ahead and use it but it just won't look right with so little to work with. Thank you all again.

    Gene
     
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  7. Preacher

    Preacher Silver $$ Contributor

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    I usually will cut a 1/4" off the chamber end and keep that along with the numbers of that build....
    No other reason....
     
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  8. skeetlee

    skeetlee Lee Gardner Precision Silver $$ Contributor

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    if you indicate up in front of the lap turn around, there is no need to cut any off the breach. I drill and pre-bore so any enlargement of the bore is machined out.
    A lot of stocks, mostly factory stocks dont have but about 1" of full diameter before the stock starts to taper. It is very common in my shop that my customers request only about one inch of full diameter " 1.200 to 1.250 barrel in front of their action. Lee
     
  9. butchlambert

    butchlambert Site $$ Sponsor

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    Lee, you might watch a barrel maker lap a barrel and then have him show you what is really there.
     
  10. Cloudrepair

    Cloudrepair

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    Butch if I can indicate ahead of the lapping bell is there any reason to cut any off?
    Other then to save a disc with the numbers on it
    ( Somthing I'm going to start doing because it is good to have that)
     
  11. butchlambert

    butchlambert Site $$ Sponsor

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    Need to chamber the dreaded 6.5 Creedmoor. I pinned it first and it was .2562. I cut 3/4" off of it and it measures .2561. Not enough to worry about.
     
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  12. Cloudrepair

    Cloudrepair

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    Thanks
     
  13. spclark

    spclark Gold $$ Contributor

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    Agreed but as I'd rather trust my 'smith to do what they prefer ("Parting tool? You're kidding, right?") I take a picture of those blank breech ends for my records.

    Used to take a rubbing (paper, pencil) but the cameras in these new fangled phone things're amazing!
     
  14. Cloudrepair

    Cloudrepair

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    Parting toolo_O?
     
  15. spclark

    spclark Gold $$ Contributor

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  16. Cloudrepair

    Cloudrepair

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    Oh I understand what a parting tool is and how they are used I just don't understand were you got the reference from. I made no reference to a parting tool or parting off a section.
    Just wondering why you mentioned "(Parting tool? your kidding right?)"
     
  17. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    I much prefer to cut some off the breach. I indicate the first 3" of bore that I am working on and you definitely measure out of round as well as belling. If I cant cut any off I will indicate in about .5", that usually gets you into good bore. I order blanks a little long so I can remove 1" off the breach end.
     
  18. Preacher

    Preacher Silver $$ Contributor

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    No parting tool for me, I use my band saw on both ends..
     
  19. GAnderson

    GAnderson Silver $$ Contributor

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    Here is an update on the barrel...before sending it back to the manufacturer I thought about it a lot and decided to take it to gunsmith and see what he thought. He looked at it and decided that it was "workable", so I called the barrel manufacturer and told them that I was going to go ahead and give it a shot...they were agreeable and said to let them know how things work out. I am pleased to say that it turned out perfect...the gunsmith didn't remove anything from the chamber end...only removed 1" from the muzzle to make the barrel 24". The cartridge is the 20 Blitz and it absolutely shoots lights out. The barrel cleaned up copper free after about 6-8 rounds and I got serious the other day and shot some very very good groups. In the end it all worked out for the best. I have pics but they are too large and I am not smart enough to figure out how to downsize them yet.

    Gene
     
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  20. hpshooter

    hpshooter

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    Thanks for the follow up! Nice to see a logical approach taken and yield positive results.
     

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