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I have been reloading 6mm Rem. shells for a long time and 4 different rifles. After only 3 or 4 loads on my cases I am always getting split necks. I think I should be getting more loads on these cases. Will a neck sizer die help the problem. Yes I do load hot but not that much that the primers are poping or anywhere near. And always necks come out looking black. So am I loading too hot or not. I use RCBS fl sizer dies. Can't think of any more info to give. Wo where do I go from here.
 

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You might want to recheck your FL dies to see if they are okay. They might just need a good cleaning. Also since you are shooting the same cases in four different rifles, this might also cause your neck spliting problem. All rifles have a slight difference in their chamber area. You might back off a couple of grains of powder too. What brand of brass are you using?:confused:
 

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Welcome to ShootersForum, kbbgood.

If you're consistently getting case neck splits after 3-4 firings, something is definitely not right. Davers pointed out the most likely problem, which is not keeping cases from each gun separated. (You have FOUR different 6mm Remington rifles? :) ) I have 2 30-'06 rifles and I keep the loads for them separate, which isn't hard because I load BT's in one of them. Even if they fired the exact same bullet, I would keep cases for each gun in different loading boxes and adjust the sizing die for each set of brass.

You do mention that your case necks always come out black; are you using a really slow powder for your handloads? Are you using the same exact recipe in all four rifles? The more you explain, the better we'll be able to help diagnose.
 

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The Hog Whisperer (Administrator)
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Maybe one of your chambers is oversized, or perhaps the sizing die is very undersized. Don't know.

You could anneal the necks but shouldn't be necessary quite that soon. Lots of guys anneal them at 5 loads but you aren't getting that far.

Run a case up in the die without the expander and see what the neck measures after that. Might shed some light on the issue.
 

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Are the cases all the same brand? I've had trouble in .45 ACP with Remington brass splitting necks in the past. The necks are thinner than Winchester and other brands, which never have given me that problem. Every maker has a slightly different geometry on the inside of cases for each chambering (SAAMI only specs the outside dimensions). This issue, as near as I can tell, is specific to particular chamberings and is not universal for the whole line.

Are you crimping your case necks? If so, how often to you trim your cases? Splits usually start at the case mouth, and trimming removes the weakened leading edge of the brass. That way it can stop a split before it starts. Crimped brass is worked more and is more prone to splitting.

The black neck means the case is not pressurized enough to obturate the chamber neck at the moment the bullet clears the case mouth. Powder that's really too slow for the bullet weight will do that, as Mike suggests. It's because the light bullet scoots out before the powder has built an adequate start pressure. If you have a chronograph you will usually also find such loads are characterized by a higher spread in muzzle velocity than a better powder choice will do. If you tell us your load we can get a better sense of that.

Try segregating your brass by gun, as Jason suggested. If there is a large chamber like Mike mentioned, segregating will diagnose the problem as the splits will all happen in the cases fired in that one gun.
 

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The Troll Whisperer (Moderator)
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Four different chambers with four different final finishes, plus 4 - 5 firings of hot loads = split necks and stretched cases which are most probably over max length.
 

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I seriously doubt there's anything wrong with your barrel. I've always found the 6mm to be hard on brass for some reason and I've been shooting them since 1969. I've got one that does the same identical thing using the RCBS full length die. I'm only shooting 44 grains of H-4350 with 85 grain Seirra HPBT Game Kings and it's done that from brand new. Until I quit full length sizing, Five - six reloads were max, sometimes only three or four. The die compresses the neck way more than it needs to be, you probably have to apply a good bit of pressure seating the bullet. Get you a Lee collet die (about $20) and work with adjusting it until you get a slight interference seating the bullet and aneal the brass regularly, every four loads. This rifle will shoot one hole groups at 100 yards all day long.

I find it works better if you throw Lee's directions in the trash. For setup, take the mandrel/primer punch out and screw the cap all the way back down. Start screwing the die down in the press with a case in it untll the handle lightly cams over. Using a bullet, check the neck size, it will probably still be way too loose. Start minutely screwing the die down and caming the press over with the case in it. Check bullet fit each time. When you get a snugg fit just and can just barely get the bullet to start in the case. Put the mandrel back in and try loading a couple and see how the bullet goes in. Should take very little pressure to seat the bullet. If it's too loose with the mandrel, try going down with the die a few thousanths. That, or just leave the mandrel out and make it a two step process. Deprime them with the mandrel in and then neck size with the mandrel out. The two step process is what I use when I'm wanting my most accurate loads.

Another option is a lot more expensive, but you can get you the Redding Bushing die and bushings to get your fit right. This can get a little aggravating and expensive if you don't neck turn you're brass

Might try taking a chamber mop and put some JB on it, put it in a drill and lightly polish the chamber, DON'T get carried away doing this. This will insure the bullet is seating firmly against the bolt face. I've had this to cause one to destroy brass quickly also.
 
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