reloading ?- brass difference



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  • reloading ?- brass difference

    My 300 win seems to love 75 grains of H4831sc with 180 Horn. BTSP in win cases with CCI mag primers. It routinely (not every now and then) groups them into less than an inch at 100 yards. Awhile ago I threw away my brass. It had been loaded five or six times and since I full length size them, I thought it might be time for some new ones. I loaded up 50 of the same load in once-fired Federal brass. I didnít change anything in the load except the brass. I didnít adjust the dies at all. I used the same powder from the same canister. (New box of bullets though, but the same bullet.)
    Yesterday I went shooting with a friend. My first group went over three inches. Iíd given the rifle an extra thorough cleaning, so I thought maybe I just needed to foul the barrel. (Even though Iíd fire-lapped the barrel years ago with that Tubbís kit from Cabelas and the gun usually puts them in the group from a clean barrel.) I let the gun cool and shot another group. Another horrible group. (Plus three.) I then shoot some of the old reloads, with everything the same except the brass. The group was .7. Shoot another group with the new reloads. 2.7. I cleaned the rifle again and tried some of the old loads again. .9. I checked my action screws. All fine. I checked the scope bases. All fine. I shot 25 of the new reloads, and they all grouped horribly.
    When I shot the Federal factory loads awhile ago to get the brass, they all grouped about 1.5. I came home and weighed the Fed brass. It averaged 254.5 grains. The Win. Brass was 249. Thatís like 2%, I canít see how that would make that much difference. Besides getting good groups with my old loads, I got great groups with my friends .338 and 270, so I donít think it is my form.
    I apologize for being so long winded, but Iím stumped. Do any of you have with more reloading experience have any ideas about what Iím overlooking? I canít see the brass making that big of difference, but donít know what else it could be. My rifle has the BOSS on it. I tried several different settings, and it didnít seem to help. All of the groups with the new loads were really bad. I only have a few of my old loads left, so any help would be greatly appreciated! Thanks.

  • #2

    I don't know but the first thing I would check if indeed EVERYTHING else is the same including seating depth is check out the vel of the loads in the new brass. Also....same powder lot #"s?


    • #3
      Heavier brass means you have less powder room, and hence slightly higher pressures. Perhaps more important different brands of brass will have different neck tension on the bullets. Those are some possible causes of the difference in accuracy.

      Asside from that, some guns will shoot almost any load well, while others seem to need the planets to align to get a good group. Perhaps your 300 is a finicky gun.

      As has been said before and wisely so, whenever you change any componet, ie brass, powder, bullet or primer, you will have to work up the loads again. Different brass and a different lot of bullets is changing two things. Sometimes that has no effect, sometimes as you have seen, the effects are dramatic.

      I would recomend measuring the neck dia of loaded rounds from the old brass vs new, as well as measuring neck thickness. If the older brass had a thicker neck, that will provide a bit more neck tension, as well as providing better alignment of the case in the chamber.
      Those that are successful in Alaska are those who are flexible, and allow the reality of life in Alaska to shape their dreams, vs. trying to force their dreams on the reality of Alaska.

      If you have a tenuous grasp of reality, Alaska is not for you.


      • #4
        Changing anything on a load, to include the primeer or brass, may effect the accuracy of your load. Go back to Winchester brass.
        I changed my "pet" 7mm Rem Mag load and was shocked and the difference the different components made.


        • #5

          When you changed brass, you didn't mention if you checked the new case length against the old ones. Any time I change brass, brand for brand or otherwise, I check the length of the new case and trim them a set length I've used for 30 years. I then take one of the empty cases (no primer or powder) and start a bullet in it and I finish seating it in the action. I do seat it a tad more, just enough where it isn't tight against the lands. I don't crimp my bullets but alway keep an eye out for any that might get bumped. There have only been a couple over the years, but they seat pretty tightly. I usually load 20 rounds, go fire them and then repeat the above process.

          Over the years, I have used this exact same method, powder, primers and bullets with no change in grouping, yet, I have used a couple different case manufactures.

          Every gun is a little different and so are case lengths. Sounds like your old cases were pretty good, so measure one and go from there.



          • #6
            Brass bugaboos


            With everything else but brass the same I would say you woes are likly to be the brass neck thickness and specifically non uniform thickness. Honestly, this is common with Federal brass. The Win brass has thinner and much more uniform thickness in the neck.

            When you full length resize the case, the cartridge head spaces on the belt and the Federal brass is likely a little loose in this regard. This allows the cartridge to lay down in the bottom of the chamber and is mis-aligned with the bore. Appearantly the Win brass was a much better alignment. When you full length size cases they typically do not align with the chamber because the body and shoulder don't touch the of the chamber wall. Partial resizing will be better, don't push back the shoulder. These things plus the variation in the neck wall thickness will kill accuracy.

            Kurt also brought out a good point about the case length, possibly too long. This can cause pressure as well as accuracy problems. Did you by chance chronograph these new loads to compare velocities? That could be an indicator of the pressure.

            The brass is the most important component as for accuracy and should not be taken for granted. I would say 95% of accuracy problems are the fault of the brass. Of course this includes what we do to it or don't do as needed. Correct sizing, and trimming and it must be absolutely uniform throughout. I have never had good luck with the Federal brass and in the belted mags, if I can't get Lapua or Norma I definately want Winchester. It's not such a problem child in the standard cases, just belted.

            Another note here, I just noticed Paul's comment about neck tension and that's true. The Federal is thicker and will be tighter after sizing and that will add to the problem. Just toss the brass and go back to Winchester and just size down the the start of the shoulder, don't bump it back.

            Good shootin'.

            Is there nothing so sacred on this earth that you aren't willing to kill or die for?


            • #7

              Good points on the cases. I've pretty much stuck with Winchester, and some R-P brass. Can't tell much difference between those two. I don't care for the Federal so never use it.

              I use 175 gr. Speer Mag tips and they seat about 1/8 in short of the crimp ring by the action seating method. There have been pro's and cons on that approach with some seating the bullet tight against the lands, some backing off a bit, and some won't do it at all. Seems to work in my old Ruger and I haven't seen any signs of over-pressure.

              always interested



              • #8
                If you are looking for accuracy, don't full-length resize your brass until you are having a hard time chambering it. Neck sizing does not work your brass, thus does not contribute to early case separation as doesfull-length resizing every loading.

                Neck sizing also preserves the expansion to chamber fit, which means your getting optimum bullet alignment with your barrel. You might also try only sizing half of the neck, another aid to centering bullet to barrel.

                If you are really trying to develop accuracy loads, you might want to investigate Lapua or Norma brass. Kind of spendy in .300 Win Mag but it is "the best". I've used Lapua in .308 Win and Federal Match brass in .300 Win Mag; the Lapua is perfect, the Federal was okay.

                Might also try annealing your case necks. I've never done it, but I don't shoot one lot of brass a whole lot. Annealing will restore some elasticity to case necks when they get brittle. Years back I bought some Speer-DWM cases, they were annealed as were Norma's (I think).

                Might also try using loads in the mid-range of velocity for longer case life and (maybe) better accuracy.


                • #9
                  accuracy problems

                  That is weird. My old 7mm is tempermental likes a specific load of retumbo. But my brass is half federal and half winchester half remington and they all shoot the same. I understand your full length sizing the 300 as my 7mm and my new 300wsm both make chambering difficult without substantial resizing after only one use. And you dont want those problems in the field. It sucks to realize that you are hunting with a gun and the cartridge doesnt fit. At least you have the option of going back to only Winchester brass to hope that solves the problem. Good luck.
                  ďI come home with an honestly earned feeling that something good has taken place. It makes no difference whether I got anything, it has to do with how the day was spent. ď Fred Bear


                  • #10
                    Brass and Sizing


                    You and many others have said that their brass doesn't fit if it isn't full length resized. I really don't understand this. If brass was fired in your rifle it should go back in easily, it came out easily right?

                    Any brass which does not chamber easily after just neck sizing has been fired too many times, was a high pressure load, came from another rifle or you have an odd shaped chamber which makes the brass lop sided when fired.

                    After only one firing, any and all brass should chamber with out effort when just neck sized. Now after several firings it will expand at the base enough to make a harder bolt closure and can be fixed with full sizing or a body sizing die. There is absolutely no advantage to making handloaded ammo if you set the shoulder back to a minimum SAAMI specs, must fit every chamber, type of round.

                    I see this comment from many folks here and it shouldn't be that way. I honestly think it was started by some sales clerk who had never fired a gun or reloaded a round. NECK SIZING is adequate for once fired brass for hunting loads. I have fired way too many rounds of handloaded ammunition to ever believe otherwise. I would only use once fired good quality brass for my hunting loads (always have) and make sure they were trimmed to even length and fully prepped and expect them to perform flawlessly. They always have.

                    If you refer to an Autoloader, pump or lever action rifle, then there are other reasons and techniques for sizing cases, but for a bolt gun, it will fit.

                    Good shootin'.

                    Is there nothing so sacred on this earth that you aren't willing to kill or die for?


                    • #11
                      Thanks all

                      Thanks for all the information. After reading the posts I checked the length. It was fine. I checked the neck thickness. It was a lot thicker. I guess with the heavier cases and the thicker necks, it ruined the harmonics of the load. I was just really suprised to see such a huge difference. Rather than borrowing a neck-turner and working on all the cases with what sounds like substandard cases, I'll just pick up 100 more Winchester cases when I go to Sportsmen's.
                      Also, thanks for the info on neck-sizing. I have read about it, but always thought for reliability I should full-length size. I'll give this a shot too. Thanks again.


                      • #12
                        Amen Murphy!


                        • #13

                          Man that sounds pretty bad. Murphy makes some very good points. If you are full length sizing your brass you are taking away one big advantage to reloading. The fireformed brass that comes out of your gun should only be neck sized. That fit that is made when the brass was first fired in your chamber is one of the greatest benefits in handloading. As it is related to accuracy anyway. If you say it wont fit, you should read up on neck sizing and the subtle technique of doing so. There is no way it wont chamber. Something is wrong here. I am certainly no expert, but I think this is impossible except for the most exacting custom chambers. Factory chambers are made to handle all kind of crappy ammo and have huge tolerances. Necksizing will get you better accuracy (by far) and the added benefit of extended case life. When you changed your brass, you changed the entire recipe. I would try to get a batch of say 500 winchester brass. Be sure it is from the same lot. Weigh each individual case on a digital scale and pair them in batches that are most similar. They will fluctuate. Seperate them. The difference in weight indicates a difference in volume, which affects pressure, which affects barrel harmonics, which affects accuracy. It is a big deal. Weigh the cases. If you wind up throwing away 10-20 % of the cases due to irregular weights it would not surprise me in the slightest. That is why you bought 500 in the first place. Pair the cases up in batches by weight (volume) then start your recipe making process over again. When you get that magic combination, you will have a few hundred brass cases to play with. And if you are neck sizing (I strongly suggest this) these cases will last a long, long, time. Sounds tedious I know but enough little things start working against you, before you know it you will be shooting 3" groups. Oh.. Yeah. You mentioned you had cleaned the gun recently. I dont know how involving a cleaning this was, but you may want to take a torque wrench to your trigger base plate. The front screw being too loose has needlessly sent many a rifle back to the manufacturer claiming the gun was a lemon. Those two screws have to be torqued to exact specifications or your barrel harmonics will be erratic. I would check these screws. Hope you get it figured out. We have all been there. The forementioned was a hard learned lesson by yours truly. Had a Weatherby Vanguard in 300 wby that couldnt hit a baseball at a 100 yards. 10 minutes with a friend who had seen this before and a little reloading and it has been shooting sub moa for 4 years. One of my favorite rifles and I would have sold it for half price just to get rid of it at one point. Good luck.
                          The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.


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