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looks like gases leaking past shoulder?

 
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  #1  
Old 12-07-2013, 01:17 AM
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looks like gases leaking past shoulder?

Folks, I think I got a problem here, and need some input. Got my builder back from smith, mounted stock and scope, headed out to break in barrel. First round, bolt closed real hard. Actually sheared/smeared some brass off the head. Touched it off, and the bolt lifted ok. Re chambered ok, and closed again ok. Came out looking clean, no signs of gases anywhere on outside of case. 2nd round closed a little easier, ejected ok, also clean. 3 rd , hard to close, although no brass smearing on head, and powder residu around case mouth. 4th and 5th about the same. 6th round, more residue , farther down the case, and a shiny mark at just above the top shoulder radius, but only half way around. Round 7, hard to close, stiff bolt lift, and more residue. 8th (and last ) round, sounded kinda strange, like tik-bang, lots more bolt lift, shinier half moon around neck, and powder fouling in the rim area. The pictures are of the last shot, I'm just turning the case a little. These are not hot loads, new brass full length sized and trimmed to length hand loads. 338 378 Weatherby. I'm stumped, discouraged, and I'm hoping somebody out there can shed some light on this. Thanks.looks like gases leaking past shoulder?-20131206_182840.jpg

looks like gases leaking past shoulder?-20131206_182943.jpg

looks like gases leaking past shoulder?-20131206_183043.jpg
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  #2  
Old 12-07-2013, 01:27 AM
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Re: looks like gases leaking past shoulder?

Were you cleaning between shots? If so, you may not have gotten all the bore cleaner out of the chamber. Which doesnt allow the case to stick to the chamber walls and may cause what you are seeing.
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Old 12-07-2013, 02:06 AM
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Re: looks like gases leaking past shoulder?

Wow, could it really be that simple? Yes, I was cleaning between shots. So maybe dry it up and try a couple more ? Got some aerosol Rem Clean, would that work? How would it act if the chamber/barrel is not square ?
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Old 12-07-2013, 02:41 PM
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Re: looks like gases leaking past shoulder?

A wet chamber will cause all sorts of havoc. It will make it act like you have massive pressure when indeed none is present. Gas leaks, dents and flattened primers are the big ones. If the bore is wet it can cause damage in the bore. Dry it with some dry patches. No spray.

A crooked chamber will not show anything on the brass. It can only be seen with a borescope or the best way is taking it apart and dialing the barrel in a good lathe. Then it can only be checked if the same technique is used as the guy that built it. If you check it with a different technique it will show way off.
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Old 12-07-2013, 02:52 PM
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Re: looks like gases leaking past shoulder?

I'm with Riley, you have a wet hole.

The soot/swirl marks on the case are real indicative of a wet chamber.

Far as hard bolt closing, you say you FL resized the brass but did you check the shoulder datum against a previously fired round?

I typically bump the shoulders back 0.001-0.002. Keep in mind that all bottleneck cases loacate/headspace on the shoulder datum, even your round shouldered Weatherby caliber.

Contrary to popular opinions, you can bump shoulders with an ordinary FL non bushing die, I do it all the time.
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Old 12-07-2013, 03:09 PM
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Re: looks like gases leaking past shoulder?

How would you bump a shoulder without a fl die?

A problem with current head space concerns is some smiths are pushing past zero headspace and actually going negative. This can cause a problem where the FL die is not short enough. The only fix is to shorten the die or the shell holder a bit.
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Old 12-07-2013, 05:56 PM
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Re: looks like gases leaking past shoulder?

Ok, thanks, that gives me something to chew on. Its fresh from the smith, new barrel and bolt head, so I dont have any previously shot brass. However, I believe that negative headspace thing is in play here. The eight spent cases from yesterday chamber very easily, but the live rounds dont. Takes a bit of work to close the bolt. Last night, I noticed a couple of burrs on the back of the lugs, I could hang my finger nail on them, so I disassembled the bolt head, and carefully filed the burrs off. I figured it couldn't hurt, as long as I did not change the lug length or engagement area. Its a little smoother, but still hard to close on a live round. Think I'll pull a bullet to get an empty, and start fiddling with the shell holder, try and bump the shoulder down. Sidecar Flip, would you explain shoulder datum for me, please? I'm dont know what that means. Thanks to everyone for their time.
Gregg
PS Do Savages benefit from bolt lapping? If my chamber is real short, would carefully lapping the lugs help?
Gregg
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