Extraction problems continue on my 6x284

[Ironworker]

Had a gunsmith do a chamber cast . Neck is .276 Earlier I couldn't insert a bullet into fired case. So I turned neck down to .273 fired the round and now I can insert a a bullet into fired case but its snug. Made sure I was turning necks all the way to end so as not to be creating a false shoulder. The loaded rounds chamber with zero resistance. Full length sized ,die is set correctly. Upon firing there is no resistance to when I begin to cam the bolt open. Its when bolt is fully camed open does the cartridge stick ?But firing same load in virgin brass there is ZERO problem ! On 2nd and 3rd firings of cases there are No shinny ejector marks on brass,no enlarged primer pockets and I'm getting well under 1/2 MOA groups buring 52grs of Retumbo behind a 105gr Berger Hybrid. Avg velocity out of 8 rounds was 3280 out of a 30" Brux bbl. This is 3rd bbl in this caliber on this rifle never had these problems with other bbls ? Gunsmith looked at Chamber cast and he said there nothing wrong ????

 

[jonbearman]

Did your smith look at the cam on the bolt to make sure it isn't worn? Sounds like primary extraction is little to zero. How hard is it to get it to open? Do you just tap it or do you have to pound on it?

 

[deadwooddick]

Tagged, since I have exactly the same issue w/ a BAT actioned, Bartlein barreled 6.5X55 Swede loaded w/ 140 SMKs in front of 45.5 gr. H4831SC and CCI200.

Synchronicity is alive and well.

 

[Raythemanroe]

I would guess not sizing fully or trimming maybe.. Using Federal brass? That stuff seems super soft.. Final guess would be timing.


Ray

 

[jonbearman]

With the lazer cartridges,I full length size all with no exception. Ray is right or the chamber reamer is at minimum clearance and if you don't full length size you will undoubtedly be in trouble. My friend competes with 6ppc and full length sizes them always and he won the nationals like that.

 

[Ironworker]

Did your smith look at the cam on the bolt to make sure it isn't worn? Sounds like primary extraction is little to zero. How hard is it to get it to open? Do you just tap it or do you have to pound on it?

Lifting the bolt after firing a round is easy. Its when its completely to top of cam that it sticks and times I had to hit it with a hammer. One light hit and its out. I'll try polishing a case or take a felt pin and mark it. Gun smith thinks I still have a maybe a thousand more rounds of life in the bbl .

 

[Ironworker]

Why is virgin Lapua brass the first firing problem free ?

 

[Ironworker]

I watched a Video on" You tube" about the formation and removal of the "Doughnut" . I ran a feeler gauge inside the neck and I think I feel it !

 

[Klong]

I would back off the load by say 3 grains and see if the problems remains.
it sound like a sizing issue though.

 

[rickiesrevenge]

Is there a click when the bolt gets to the very top of the stroke? Even if your full length sizing it doesn't mean your sizing die matches the reamer. Could be that the die isn't sizing the base enough. It would explain why new brass works fine and fired brass doesn't. The case head takes a couple firings to expand to the point where it could cause problems. If your not getting pressure problems all the time I seriously doubt that your cases are too long and need trimmed.

 

[CJ6]

Had a gunsmith do a chamber cast . Neck is .276 Earlier I couldn't insert a bullet into fired case. So I turned neck down to .273 fired the round and now I can insert a a bullet into fired case but its snug. Made sure I was turning necks all the way to end so as not to be creating a false shoulder. The loaded rounds chamber with zero resistance. Full length sized ,die is set correctly. Upon firing there is no resistance to when I begin to cam the bolt open. Its when bolt is fully camed open does the cartridge stick ?But firing same load in virgin brass there is ZERO problem ! On 2nd and 3rd firings of cases there are No shinny ejector marks on brass,no enlarged primer pockets and I'm getting well under 1/2 MOA groups buring 52grs of Retumbo behind a 105gr Berger Hybrid. Avg velocity out of 8 rounds was 3280 out of a 30" Brux bbl. This is 3rd bbl in this caliber on this rifle never had these problems with other bbls ? Gunsmith looked at Chamber cast and he said there nothing wrong ????

So is .273 dia. with bullet seated ? It sounds to me like the neck is still too thick. If the bullet is SNUG in a fired case the neck is TOO thick..

 

[Raythemanroe]

excessive head space?





Ray

 

[savagedasher]

Is there a click when the bolt gets to the very top of the stroke? Even if your full length sizing it doesn't mean your sizing die matches the reamer. Could be that the die isn't sizing the base enough. It would explain why new brass works fine and fired brass doesn't. The case head takes a couple firings to expand to the point where it could cause problems. If your not getting pressure problems all the time I seriously doubt that your cases are too long and need trimmed.

The best way to check what he is saying .Take a case that is tight with a black black marker blacken the whole case.includeing the head, close the bolt and remove the case. Where the shine spot is will be where the case is tight, Larry

 

[Ironworker]

Is there a click when the bolt gets to the very top of the stroke? Even if your full length sizing it doesn't mean your sizing die matches the reamer. Could be that the die isn't sizing the base enough. It would explain why new brass works fine and fired brass doesn't. The case head takes a couple firings to expand to the point where it could cause problems. If your not getting pressure problems all the time I seriously doubt that your cases are too long and need trimmed.

The best way to check what he is saying .Take a case that is tight with a black black marker blacken the whole case.includeing the head, close the bolt and remove the case. Where the shine spot is will be where the case is tight, Larry

Ok I blackened a case completely as advised . Inserted it in chamber. From closing the bolt some of the black on case head was scratched off,on case body a thin line about 3/32 wide was also scratched off that ran from case head to half the case body . That's all ? So I ran a feeler gauge inside case neck and I feel a "Doughnut" This forum has a very informative article about neck turning and getting rid of that Doughnut along with problems it can cause. Plus every thing you ever want to see is on You Tube about neck turning and cleaning up this "Doughnut". So I ordered a inside Wilson neck reamer from Sinclair and I'm going to turn another 1/1000th from the neck so a bullet fits loosely in fired case.

 

[savagedasher]

Is there a click when the bolt gets to the very top of the stroke? Even if your full length sizing it doesn't mean your sizing die matches the reamer. Could be that the die isn't sizing the base enough. It would explain why new brass works fine and fired brass doesn't. The case head takes a couple firings to expand to the point where it could cause problems. If your not getting pressure problems all the time I seriously doubt that your cases are too long and need trimmed.

The best way to check what he is saying .Take a case that is tight with a black black marker blacken the whole case.includeing the head, close the bolt and remove the case. Where the shine spot is will be where the case is tight, Larry

Ok I blackened a case completely as advised . Inserted it in chamber. From closing the bolt some of the black on case head was scratched off,on case body a thin line about 3/32 wide was also scratched off that ran from case head to half the case body . That's all ? So I ran a feeler gauge inside case neck and I feel a "Doughnut" This forum has a very informative article about neck turning and getting rid of that Doughnut along with problems it can cause. Plus every thing you ever want to see is on You Tube about neck turning and cleaning up this "Doughnut". So I ordered a inside Wilson neck reamer from Sinclair and I'm going to turn another 1/1000th from the neck so a bullet fits loosely in fired case.

Do me a favor the case that was tight and use 320 paper or 600 rotate the bottom half includeing the head take 1/2 to one thousand off. .I will bet the problem will be found.. The chamber could be cut on the tight side. Larry

 

[rcw3]

Why is virgin Lapua brass the first firing problem free ?

Ironworker

A big issue with a lot of the 6x284, 6.5x284 and 284 chambers is they run only around .500"- .501" at .200" forward of the bolt face and Lapua brass runs right around .499" at the web and .001"- .002" is just not enough clearance in those dimensions (i.e. the web helps the brass just forward of it spring back from re-sizing and get "fat" there and after a firing or two, even if you re-size you get a sticky bolt on extraction). This is a common issue and that's why you don't see it with new brass but with fired and re-sized brass it becomes and issue. There are solutions I can elaborate on if desired.


Robert

 

[mikecr]

Other than possible action timing issue, it could be a combination not enough barrel steel around the chamber, clearances that are too large(like 2thou at webs), and hot loads.

The answer is not always LARGER clearances, or MORE sizing.
Usually, the answer is a better plan to begin.