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Is powder residue on should & neck a safety issue?

 
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  #8  
Old 05-16-2011, 11:17 PM
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Re: Is powder residue on should & neck a safety issue?

do you remove oil from the chamber and bolt face before shooting your rifle?
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  #9  
Old 05-17-2011, 12:01 AM
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Re: Is powder residue on should & neck a safety issue?

Quote:
a picture of the whole case, for three pieces
I just wanted to see if the cases had signs of case head separation, since the shoulders looked so worked.

This is what I was looking for, (something I don't see on your cases.)



The dark band in the light area is the point where the separation is taking place on this 30-06 case. I used a bent paper clip to feel the inside of the case to confirm the condition.

Quote:
Has anybody had a similar experience where the measured head space didn't seem to change, even as the dies were adjusted down more and more?
Seems bizarre to me. Maybe the dies are designed to go only so far, to stay within SAAMI specs?
I have never used those measuring devices; but I do think the adjustments made had shortened the case to below your chamber's specs.
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  #10  
Old 05-17-2011, 12:56 AM
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Re: Is powder residue on should & neck a safety issue?

Quote:
Originally Posted by SakoShooterSD View Post
Has anybody had a similar experience where the measured head space didn't seem to change, even as the dies were adjusted down more and more?
This can be an issue(among many) with FL sizing, depending on your cartridge design, chamber, die match, and load. As the die works down the case body and sizes the lower body(more than anywhere else), it's squishing brass upward(toward least resistance), back into the shoulders & neck, defeating any bump. You might also notice the brass growning in OAL, donuts forming, and frequent need for trimming.
IMO, this is a point where you've gone too far for THAT die & YOUR chamber formed brass.
You shouldn't have to work brass hard for a standard bump.
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  #11  
Old 05-17-2011, 11:23 AM
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Re: Is powder residue on should & neck a safety issue?

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Originally Posted by str8shoot View Post
I bet it is the powder. A faster powder will expand that case faster (before the burning powder comes up the case neck). I think that load actually needs a little more pressure.
Retumbo is a pretty slow powder for the 7 mag. It works well for the heavy bullets. I prefer h-1000 to retumbo and I shoot mostly 160-180s in my 7mags. If I were gonna try some 150s I'd use H-4831, it seems to work pretty well with most weights.
Hodgdon lists a max load of 72.5 gr Retumbo with a 150 partition. I really think you are under pressure with that load, have you tried higher charges of Retumbo? Do you haven't any other powders on hand to try?

As far as bumping the shoulder, I actually had to grind down the bottom of my die to be able to bump my shoulder just .002. I removed enough material that my shell holder wouldn't touch the die when it is set up correctly.
Hope any of this helps.

Str8shoot, I think you may be correct!
Of course, the powder is just part of the question in this "multi-variate" problem.

Yes, i think 68.9 gr is below the max recommended charge for Retumbo (though it is not listed specifically for 150 gr bullets in my Barnes manual), . . . but seems to produce very good velocities, very consistently at 2964 fps (+/- 9). As such, it is a very efficient load, but . . . may be part of the reason I'm seeing the powder fouling on the shoulder and neck . . . especially if these cases have been overworked by 3 cycles of FL resizing with .008" of shoulder movement. I like the Retumbo because it seems to have a bigger sweet spot, in terms of consistent performance in the face of changing temperature.

I have tried higher charges of Retumbo, up to 70.5 gr with 150 gr bullets (and up to 73 gr with 140 gr bullets) . . . but I do not know whether the same shoulder fouling occurred. I will have to look at that again.

I also have IMR 4831 powder on hand, which has also been very good in this gun, and seems to produce higher pressures. So, I think I will try that again for comparison, though the recoil seems to go up while the velocity goes down. (Not as efficient a load.)

I have not tried the H1000. I was planning on trying some VIT N560, but everybody seems to be out of it at the moment. I think it would produce higher pressures, too.

If I can get this powder fouling to go away, I'd be happy to stick with the Retumbo,
so I'll try getting these dies set up to produce just 0.001" of shoulder bump, and I may try annealing some cases, too. I hope this "problem" will go away by getting my dies set up, and reducing the work hardening on the cases.

Naigi, I don't really care what the cases look like . . . so long as they look like they are still in one piece (as opposed to a short piece sitting on the shooting bench, and a longer piece wedged in my chamber). My original question still stands: Is powder residue on the shoulder & neck a safety issue?

I don't have a good feel for when one is getting close to case head separation, though I know a guy who lost a good gun (35-338 wildcat) to it. I don't want that to happen on my 7mm Rem Mag, which I just sunk over $3k into rebuilding.

Jinx . . . I do now! ;-)

Justgoto, thanks for the picture! Know I know a little more about what to look for.

Mikecr, thanks for the note. I think you're right, the brass was getting worked beyond what was necessary for minimum bump, though I need to go back and try to sort out which head space measurements came from which die adjustments. (I may need to just start over, and so am trying to get a press set up here at my house so I can try adjusting the die and making more measurements. I may need to go get more brass and start over, too . . . though everyone seems to be out of Nosler brass for 7mm Rem Mag. I would like to try to stick with the same brand of brass, just to eliminate one more variable, though I suppose I could try another.)

Thanks for all the input, guys!
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  #12  
Old 05-17-2011, 01:21 PM
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Re: Is powder residue on should & neck a safety issue?

I would also say that it is insufficient pressure or that the shoulders had been bumpted back too much. Look at the setup of your dies. Don't push the shoulder back more than 0.001-0.002".

Secondly, if you have a rifle with a long free bore and you seat the bullets too far out, it mean that the pressure is too low in the case to push forward the shoulders. By seating the bullet deaper it would take longer for the bullet to leave the case and thus pushing the shoulder forward before the bullet leave the case. If the bullet is seated too far out, the pressure is not enough to push the shoulders forward and therefor the gasses escape and burn up to the shoulder.

The grouping suggest that there is nothing else faulty with the load.

Last edited by Reloader222; 05-17-2011 at 01:33 PM.
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  #13  
Old 05-17-2011, 02:22 PM
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Re: Is powder residue on should & neck a safety issue?

Quote:
Originally Posted by Reloader222 View Post
I would also say that it is insufficient pressure or that the shoulders had been bumpted back too much. Look at the setup of your dies. Don't push the shoulder back more than 0.001-0.002".

Secondly, if you have a rifle with a long free bore and you seat the bullets too far out, it mean that the pressure is too low in the case to push forward the shoulders. By seating the bullet deaper it would take longer for the bullet to leave the case and thus pushing the shoulder forward before the bullet leave the case. If the bullet is seated too far out, the pressure is not enough to push the shoulders forward and therefor the gasses escape and burn up to the shoulder.

The grouping suggest that there is nothing else faulty with the load.
Reloader222, thanks.
I had not thought about the bullet seating depth, but it makes good sense. I have these bullets seated for maximum recommended COAL of about 3.290", which seemed to produce slightly better groups than 0.015 and 0.030" shorter COAL. I don't yet know how far off the lands that puts these TTSX bullets, but I'm working on measuring that now . . .

My bullet seating depth measurement tool (part of the the RCBS "precision mic" kit) tells me that my chamber measures 0.020". When I use the same setup to measure one of these loaded cartridges, I get 0.008", . . . so, looking at the difference between those two measurements, I would say these cartridges have the bullet seated 0.012" off the lands. I would like to keep it around 0.010 or under if I can. (I'm a bit superstitious about guns that shoot better when the bullet has to "jump the gap". That makes little sense to me . . . though I am a neophyte at this game.)

When I put a micrometer on a bullet, it measures approximately 1.43" long (including the plastic tip), . . . and I measure about 0.82" protruding beyond the neck of the case for these loads . . . so there is about 0.6" of bullet length seated. (Base of the bullet actually sitting almost 1/4" below the shoulder). That seems like it would be sufficient, but . . . who knows?
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  #14  
Old 05-17-2011, 07:28 PM
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Re: Is powder residue on should & neck a safety issue?

I have recently been hand loading for my 7mmRM. I always get powder burns/residue on the necks, but never on the shoulder like yours. I have been using H1000 exclusively. My load is 70.5g of powder pushing 168g SMKs. I use Winchester brass and Fed 215s. I am just learning specifics of reloading, but form what I have learned, it sounds like the gas is escaping around the neck (which I think is normal). The problem is the gas shouldn't make it down to the shoulder because the shoulder should expand and seal off those gases inside the chamber at the time of detonation. That may not be a whole lot of help only to say that my 7mag doesn't get the gas all the way down the shoulder. Good luck.
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