Recrown Barrel / Brownells Chamfering Cutter?

Discussion in 'Gunsmithing' started by FiftyYardZero, Aug 6, 2014.

  1. FiftyYardZero

    FiftyYardZero New Member

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    Hello long range hunters!

    I need some advice about the crown on my new rifle and would welcome any input you may wish to offer.

    To make a short story long...

    This is a Browning BAR Longtrac in 300 Win Mag that I got a few months ago. The gun has had less than 50 rounds fired through it - just enough to break it in, sight in the scope, and go on a quick hog hunt. When I gave it it's first good cleaning, I noticed that there is a small nick right on the edge of the crown which you can see in the photo below. (Please ignore all the lint.) Anyway, I haven't had time to do anything about this since I put the gun away after its maiden voyage, and now it's time to start thinking about the upcoming season... So, would you rework the crown on this barrel?


    [​IMG]


    If so, what are your thoughts on using a Brownells 45 degree chamfering cutter to chamfer the edge of the bore just enough to take out the nick? The cutter has a caliber specific brass pilot to maintain concentricity to the bore and looks like it should do the job without having to send the gun to a gunsmith for a spin on the lathe.


    [​IMG]


    Has anyone used one of these? What was your experience? Is this a good DIY solution, or is it likely to do more harm than good?

    I appreciate any input and thanks in advance!
     
  2. .30US

    .30US Well-Known Member

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    How does it shoot now? At a recent gunsmithing course, the instructor was talking about a study written up by another gunsmith in which he intentionally damaged the crowns. He started with small nicks in minor locations and continued to major gouges. In the end, his conclusion was it doesn't matter unless you see accuracy drop off; no specific damage produced an expected drop off in accuraccy. I'd keep hunting until it has enough damage to show on paper, then look at doing something about it. If you do decide to recrown, I would recommend against a single angle on the crown. I like to have a transition angle of a few thousandths thickness from the lands and grooves to the actual crown.
     

  3. jfseaman

    jfseaman Well-Known Member

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    As was said. If it shoots, IMO don't mess with it.

    But if it don't...

    I would get the Manson kit (well, I did) or have a GS clean it up.
     
  4. J E Custom

    J E Custom Well-Known Member

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    The hand crowing tools , If used properly/carefully will do a decent job. but in my opinion, the "Best way is with a Lathe and I recommend the 11o crown.

    The short pilot crowning tools like the Brownells can chatter and are not as precise aslonger piloted tools.

    Just my opinion

    J E CUSTOM
     
  5. jfseaman

    jfseaman Well-Known Member

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    Practice practice practice.
     
  6. Barrelnut

    Barrelnut Well-Known Member

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  7. FEENIX

    FEENIX Well-Known Member

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    I agree ... and really like the one sentence conclusion. :D
     
  8. emn83

    emn83 Well-Known Member

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    It really ties things up nicely
     
  9. FiftyYardZero

    FiftyYardZero New Member

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    Thanks, everyone, for the replies and the linked article! Based on the responses, I think I'm going to leave well enough alone until I have a significant reason to recrown the barrel. If it ain't broke...

    As for how the gun shoots now, the truth is that I haven't been able to spend enough quality time at the range with it to really know what it can do. My old rifle decided it was time to retire in the middle of the season last year and I had to rush to get this gun and get it set up in time for a rapidly approaching hog hunt. So, basically, I was only able to get the scope on it and make sure it was "good enough". -- If I remember correctly, it was shooting somewhere around a 2" group at 100 yards with some 165gr Sierra GameKing handloads that my Dad was shooting at the time.

    I'm going to start working up a load specifically for this gun in a couple of weeks, so I'll be able to see how it really performs then. I just wanted to get some input on the crown before I get started in case the consensus opinion was that it needed to be fixed.

    I'll post a better assessment of how it shoots after I get a load worked up in case anyone is interested.


    Thanks again!
     
  10. J E Custom

    J E Custom Well-Known Member

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    I have seen and been involved in this debate many times and like many have an opinion and no real proof that a perfect crown is a must.

    So these are my thoughts on this subject based on over 50 years of shooting.

    The first though would be "Why Not Have a good/perfect crown". A really accurate rifle is the
    culmination of all parts and workmanship being as good as possible.

    None of the test performed are conclusive in my opinion because they depend on the conditions
    to be the same and the shooter being perfect every shot. I have shot untold numbers of groups
    and have never exactly duplicated the same group even with the same rifle and load. Bench rest
    shooters are the most likely to do this because they shoot slow and have very little contact with
    the rifle, eliminating much of the shooter error. And you will never see a bad crown on one of there rifles.

    In this game we expect our rifles to shoot 1/4 moa or less in order to be consistently accurate at great distances. We know and deal with our skills and rely on the rifle to bail us out if we don't
    perform perfectly every time so we go to great lengths to have the best rifle, ammo, conditions
    and practice as much as possible in order to feel confident we have done everything possible.

    Poor workmanship or defects do not instill confidence in most of us and even though some things
    may not matter that much if you know they could be better, they may cause doubt and lower performance/end results.

    So, is a good crown that important ? In My Opinion, Everything is important and should be as good as possible, and as we all know the crown is the last thing the bullet is influenced by so why not have a good one and not take a chance and loose any accuracy and have doubts.

    To me, It is not a question of whether or not it is important, but a question of how much effect it has on the overall accuracy potential. So why not eliminate as many doubts as possible and have a good crown on your rifle.

    If you order a custom rifle built and the rifle came in with a bad crown, would you just say or except the gunsmiths answer
    "It doesn't matter how the crown looks, it will shoot fine" I DON"T THINK SO.

    Why settle for less.

    J E CUSTOM
     
  11. jfseaman

    jfseaman Well-Known Member

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    On the effect of crown imperfections and accuracy, I'm with JE on this.

    Regardless of what someone wrote in an article, physics is physics. Per Sir Isac Newton if you disturb the projectile it will deviate. After that, what is accuracy? Per the article accuracy went from 1/2 to 3/4 and the writer considered it trivial. Math will show us that is a 50% decrease in accuracy. NOT TRIVIAL.

    I think the article was written by someone who was very bad at keeping their rifles in good shape and needed social support for their guilt.

    Where I disagree with JE is on hand tools vs. machine tools. Yes if you have a lathe setup to turn barrels and you do it all day, every day. The lathe is the tool you would use. However, if that is not the case then hand tools if of high quality IMO are a viable option but...

    Understanding at least a little about machining is IMO important.

    Digression, JE, I crowned a muzzle last night the chip from chamfering the outside of the barrel reached 4 inches before the breaking. It's about speeds and feeds, even with hand tools. When neck turning brass I often reach 2 inch brass chips.

    This is my opinion based in experience and some knowledge.

    Now regarding Brownell's tools. Me no like. The design puts a moving surface inside the barrel, contacting rifling. Constant change of angles.

    I like Manson's tools. The rod becomes rigid in the barrel. I know there is no way you can get a long, consistent chip unless the tool is stable. I would not use the hand crank version. Variable speed drivers are now standard on anyone's work bench, so use the driver adapter. To me, the hand crank version will pull the cutter off center.
     
  12. stenger

    stenger Well-Known Member

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    Lathe with a carbide tool turned really fast makes a crown look like a mirror
     
  13. jfseaman

    jfseaman Well-Known Member

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    Well yes, of course. Speeds and feeds. Anyone who believes they can get a better finish with hand tools is, well, you know.

    The original poster wanted to know if the Brownells tool could do the job. No, I don't think it can. Get the Manson tool.

    I prefer to do as much of my own work as I can and do a little for friends for the fun of it. For others there is the cost and logistics of getting the rifle to a gun smith.