Click on Extraction??

K

Keith Skjerdal

Member
I just got my hands on some new Norma 6XC brass. Necks measure very consistent as does the new empty case weight. I have found via smoking a case that the only area I have to size the Norma 6XC brass in is at the base. My chamber/case (6mm - 250, 30 degree shoulder) is based of the 250 Savage case as the parent with a .465" base and the 6XC has a .467" base (best I can measure with calipers).

I have a modified, cut-off 250 sizing die (only has the .320" of the very end of the original 250 die, just enough to go into the press with about 2 threads to hold it in place) that sizes 1/2 the case body down to the base. The new base diameter is .466" but a chambered empty 6XC sized with the above die makes a click sound when I extract it and I have to use a hair of leverage to extract the case, were it makes a "click" sound to get the bolt to open enough to move it rearward. I fells good going in, with just a hair of pressure needed to close the bolt with the firing pin removed.

Any Ideas what is making the case extraction go "click"?
 
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I think the web of the case is jamming in the chamber causing hard extraction to break it loose... the click is the bolt after it pops through the initial extraction cam... ?
 
Yes I think so too. Maybe I have to size the base down more, like .002" smaller than the reamer... maybe have to cut off a SB 308 die next :(
 
That's what happens when people insist on undersized chamber reamers. I got over that 20 years ago. Like many others, I ran into the same problem with 6BR chambers which were just a bit tight at the base. I decided there was little reason to chamber for a standard cartridge if I couldn't use common brass. Regards, Bill.
 
This is coming from a totally non qualified nontechnical perspective, so stay away from my soft bits.

Could you have the chamber polished out a tad?
 
John Kielly,


Yes, you could even polish it out yourself if you are equipped to remove the barrel. The reason for removing the barrel is that IMO you should do your polishing with the barrel turning or you WILL egg-shape the chamber. I've polished them out using a small drill-press laid on its side......now this is hokey but it works :)


I guess you could even clamp a hand drill to the table to drive the barel......


You lay the setup down on a table and build some sort of a cradle for the barrel, drive it with a flexible driver chucked into the drill (press) on low speed. By "flexible driver" I mean something like a section of hose or a shaft made of something (I've used an aluminum arrow shaft) that's simply taped to the end of the barrel. Once you've jerry-rigged a setup which turns the barrel you can run a sandpaper lap into it.....this is just a slotted wooden dowel with a flap of sandpaper in it...... and work the end of the chamber. Of course care must be taken that you don't round off the sharp edge of the chamber. For the final touch I'll use a fired case with Clover oil-based lapping compound on it.


It's messy


It's slow


But it will get the job done.


IMO the last step should be to go back to the dowel and using FRESH 320 grit sandpaper try to produce a crosshatched 320 finish inside the chamber. Getting the chamber too highly polished makes it stickier, again IN MY OPINION! :)


hth


al
 
Keith, you can also spin a case and polish the case head to bring its OD down to see if the KS click disappears. Start with a KS clicking case and polish it down in .0005 - .001 increments... just a thought.
 
In rereading my prior post I find it to be unclear :eek:

NOTE than when I mention running a lap or an abrasive-coated case into the rotating barrel, I also mean for the LAP to be turning!

In other words, BOTH the barrel and the lap must be driven, the barrel slowly and the lapping tool quickly.......... like the lap should probably be in a Dremel tool or similar.


The LAP does the work while the barrel is spinning only to even out the lapping effect.


al
 
Yesterday I cut off the end of a 308 SB die so I had about two threads to hold it in the press. Next I drilled out some of the upper end of this remaining piece of SB die. This "short die" sizes the *NEW* unfired Norma 6XC brass down enough in the base area (now down to .462") so there is no click now on primary extraction. Still have to polish it up some as it scratches the brass pretty good, but she chambers nice and extracts without any issue now, then size all of what I have for my 6-250 30 degree and go fire form it. Maybe I will wait until this barrel goes south before I fire forming these 400 pcs for Norma 6XC into my chamber. My barrel has approx 3000 rounds down her now and I want to get another 1000 or so thru her if she will hold under 1/2 moa, if not this existing barrel becomes the fire former barrel and I will screw a new one on.

Thanks guys.
 
Keith, you must have lots of time on your hands....I wish I did. Thankfully I have a 6mmxc reamer and brass. I couldn't imagine doing all of this.....

What brass did you start with? Norma ? Nosler?
 
You have temporarily fixed the problem... I would make sure the chamber is larger in the new barrel down the road...
As Bill did 20 years ago I also gave up on super tight body dimension reamers... they cause more problems that any benefit they may offer.
 
Dennis Sorensen said:
You have temporarily fixed the problem... I would make sure the chamber is larger in the new barrel down the road...
As Bill did 20 years ago I also gave up on super tight body dimension reamers... they cause more problems that any benefit they may offer.
Click to expand...

Dennis, what do you mean by super tight body dimension reamers? Do you use any min spec reamers? Regards
 
Joe Ponto said:
Dennis, what do you mean by super tight body dimension reamers? Do you use any min spec reamers? Regards
Click to expand...


Super tight = under minimum specs...

Today I use minimum specs as recommended by the reamer maker... and they won't recommend a diameter at the web that is too small... Years ago I had a custom 30-06 reamer made with a .266" diameter at the back to accommodate the small brass that was so commonly made that way... never again will I do that... I ended up re chambering because the odd correct size brass would jam tight...
 
I'm with Dennis. On my tight neck chambers that I'm going to build the resize dies myself, I go a minimum of .003" over the brass then the resize reamer .003 under the finish reamer. Sizing brass down smaller than the factory made it won't work well. There has to be a room for a range of motion for the brass to move in, That's expanding on firing with spring back away from the chamber walls and reducing the size during sizing with spring back. Too tight makes the phone ring. Too tight makes a click on top. Tight chambers don't make primer pockets last longer. Good brass and less pressure does. On hunting reamers I go with SAMMI specs on the body. Commercial sizing dies have to work.

Dave
 
Thanks Dennis.

You guys are brave.....smaller then min spec. I can just imagine the headache...geez where is the asperin...

Dave, how could someone think you can keep the primer pocket tight when the rim and groove of the case are not sized and a good portion of the pocket height resides in that area...
 
Here's the final product. Used my cut-off 308 SB die to size the base down (you can see the darker area of that is sized down, about 1/2 way down the case to the base and this eliminated the "click"), then a 260 mandrel to neck it, then thru a 6BR die to set the false shoulder. The last case is a formed 308 Lapua case also made into 6-250 since I have not fire formed any of the 6XC cases yet. Using the 6XC as a parent, there is a lot less work in making the 6-250 30 degree shoulder case. My case is a hair longer than the 6XC and has a smaller base size, otherwise, it is the same case.

6XCinto6-250IM005770-1.jpg
 
Joe

It's not just what's sized. It's what's supported to start with. There is roughly .155" of the case on a Remington that is hanging out the chamber. You could have an interference fit in the chamber and still losen primer pockets. Then if it's a belted case you have .220" unsupported and unsized. I bought into that idea when I first started. That's what customers wanted. I had reamers reground, now when I use them I polish out the back of the chambers a couple of thousandths. What pain the the butt.

Dave
 
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