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  • Bad factory crown

    I was tacking off the factory muzzle break on my Remington 700 338 Lapua. And after getting the break off I looked at the crown. This is a good factory crown? I hate to see a bad one. I tried to polish just the bevel so it would show up in the picture.

    And the opposite side hard to say how much off center they left the crown.

  • #2
    Most factory crowns can be improved. A few get through that are just plain terrible. I had one that I really wish that I had kept a picture of.
    Byron Boucher
    Burnet, TX

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    • #3
      How does it shoot?
      Jim H.

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      • #4
        Improving Accuracy

        A good crown is allways going to shoot better than a bad or questional one. You get more improvement for less effort than any other accurasing task. Fixing the crown and the bedding on a factory rifle provide the most payback for your effort.
        Byron Boucher
        Burnet, TX

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        • #5
          I fully understand the effects of a good crown. I also understand the deleterious effects of haphazard fixes applied without first determining the problem.

          The photo "looks" bad. However, the proof is in the pudding. What group sizes does the gun produce, and how do they compare to expectations for this rifle/caliber combination? A "poor" crown can still produce consistant groups.
          Jim H.

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          • #6
            To tell you the truth I haven't put a single round threw the gun. I am still waiting on the scope. I made a new break for it and was installing it. Along with some modifications for a future suppressor. I want this to be a 1000 yd gun.

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            • #7
              Remington (and other gun companies) has had a history of not using piloted tooling and floating reamer holders. If they run their crowing cutters based on holding the o.d. of a barrel, and the bore is not perfectly on center, you'll see an off-center crown. Extreme case in point happened about ten years ago, if my memory is accurate, when some Remington shotgun barrels were reamed and threaded for choke tubes, with the reamed hole offset to the bore by about .010" or so. The result was blown out barrels where the shot charge caught the skirt of the tube which was protruding into the bore.

              David
              David Kaiser
              “You can have peace. Or you can have freedom. Don't ever count on having both at once.”
              ― Robert A. Heinlein

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              • #8
                Jeremy,
                While you're at it, might as well pull the barrel and rechamber to a .338 Norma. Yes, I'm digging on you a little, but once you shoot out that Lapua, send me a PM. I'll help you out.

                1smalljohnson

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                • #9
                  Pardon the n00b question, but I'm stupefied by the OD threads on that piece... Having the last inch screwed in and subsequently rifled seems crazy to me. What am i missing?

                  Thx.

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                  • #10
                    Quote, " A "poor" crown can still produce consistant groups." True but....the derspersation will be larger than from a good crown. If it is good enough then it is not worth investing more time and effort. Some will wear out barrels to get the statistics to make a determation about the validity of a mute point. I came into the HSM arena to facilitate my desire to improve the accuracy of my guns. Along the way the means to the end became the end, and I now am more interested in learning the in and out of machining. What I have learned along the way is that correcting the crown and bedding produce substantial improvement. I also lap lugs and true actions but have become convinced that it is better to invest resources in good custom actions than in trying to correct something that was not done satisfactorily to begin with. Thirty five years in the waterwell drilling business taught me that it is much easier to drill a straight hole than to straighten a crooked one. The shooting games have different requirements. When I shot smallbore prone, If you droped a point you might as well pack up and go home. A perfect score was just the entry point into the X-Count race to determine the winner. Now shooting prarie dogs if I miss, I just reload and sling another one at him. I do believe that confidence in your gun helps one to shoot better with it.
                    __________________
                    Byron Boucher
                    Burnet, TX

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                    • #11
                      If it shoots good I see no point in re-crowning unless I am getting paid for it.

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                      • #12
                        Crowning improvements

                        The functional purpose of the barrell crown is to allow the bullet to exit the barrell and the confined gases to excape without imparting an upsetting or unbalanced force to the bullet. If this is accomplished then it matters not what the configuration of the crown is. There are flat crowns, round crowns, recessed crowns, 11° crowns, and on and on.....
                        What I have found to be the easiest to construct and has additional benefits is the flat recessed version with a slight 60° chamfer produced by a piloted center drill. I start by facing the end of the barrell with it being held in the steady either directly or with a trued bushing if it is a finished barrell as shown.


                        Next a 0.050 recess is cut with a very sharp HSS facing/crowning tool. The final cut is made with a sharp piloted centerdrill to a diameter just slightly larger than groove diameter. This recesses the release point slightly more and provides a guide for the cleaning rod re entering the bore.

                        The crown on Jeremy's gun could have been recut by hand with a piloted centerdrill without even removing it from the stock..
                        Byron Boucher
                        Burnet, TX

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                        • #13
                          What is a 1000 rifle?

                          What is good enough? Most centerfires will shoot a 1000 yards. If memory serves me correctly, some will shoot under 4" groups at that range. I doubt that those are based on Remington actions. I am not knocking Remingtons. I have killed several prarie dogs over 600 yds. with one. If you are serious about competeting at that range, start with a better custom action.
                          Byron Boucher
                          Burnet, TX

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                          • #14
                            This is the Remington police sniper MLR (medium long range riffle). I don’t like to look like the next guy on any firing line. The way I see it; it only cost me time and maybe a side of a carbide insert if I broke one. This gun will have a new paint job and maybe a new stock before it’s all over with. This will be a hunting rifle not deer but more for hogs, parried dogs and coyotes. This will not be a coveted master piece that you can look at but not touch.
                            adatesman- I cut the entire factory thread off. Rethreaded and crowned dead on center. I plan on using a suppressor with this gun and the factory threads wear out of round with the bore.

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                            • #15
                              There are as many theories and opinions as to what constitutes a proper crown and the reasons for crowns as there are theories and opinions regarding the proper way oil in machining. I won't get into discussing them as that is not my point.

                              When attempting to improve the accuracy of a firearm, you must start with some baseline to gauge the effects of your efforts. With a new rifle, you should first try it with a variety of loads and ammunition manufacturers to determine what it will handle the best, otherwise you could end up chasing your tail with a load that will never perform accurately in that gun.

                              The crown in the OP may or may not have an effect on the rifle's accuracy. It could cause the groups to disperse or merely displace them somewhat. Without having a definite starting point, you have no means to judge the effects of your improvements.

                              If the work is being performed in the home shop by the owner, there is little lost except time, but if the work is being performed by a paid gunsmith, much money can be spent with no real gain to be had.
                              Jim H.

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