Help with very difficult extraction

[rfurman24]

Just got my 20br together and finally had a chance to shoot it. It is very difficult to extract fired cases. Even at 28.5gr Varget under a 55gr Berger it is more difficult than I have ever felt. Todd Kindler told me this is a very very weak load so it should not be a pressure issue. Sized cases cycle fine. The only measurement I see a difference between sized and fired cases is about .002-.003 shoulder bump and the neck goes from .233 to .235 in a .236 chamber. I am at a loss.

[sinman]

is the chamber dirty or ruff?

[rfurman24]

Not that I can tell. I tried cleaning it just in case. I did just discover that I can not easily slide a bullet into a spent case. Could this be a result of or a clue to my problem?

[pdog06]

Make sure the front action screw isnt too long.

I had this happen with my 6br. The action screw was too long and when a round was chambered the bolthead would ride up on the long action screw(basically pushing the case to the top of the chamber). Once it was fired the bolt did not wanna lift because the brass fireformed to the chamber that way . An unfired case would go in just fine, but a neck sized formed case wouldnt chamber cause the first firing deformed the brass(ruined 15 pcs of Lapua brass before I figured it out).

May not be your problem, but thought I'd mention it so you dont have to find out the hard way like I did. Only had to take a smidgen off the bolt too. Just next round you fire try to loosen the screw and see if it frees up the bolt.

[rfurman24]

Not that I can tell. I tried cleaning it just in case. I did just discover that I can not easily slide a bullet into a spent case. Could this be a result of or a clue to my problem?


There seems to be mixed opinions on this on 6mmbr.com

[rfurman24]

Make sure the front action screw isnt too long.

I had this happen with my 6br. The action screw was too long and when a round was chambered the bolthead would ride up on the long action screw(basically pushing the case to the top of the chamber). Once it was fired the bolt did not wanna lift because the brass fireformed to the chamber that way . An unfired case would go in just fine, but a neck sized formed case wouldnt chamber cause the first firing deformed the brass(ruined 15 pcs of Lapua brass before I figured it out).

May not be your problem, but thought I'd mention it so you dont have to find out the hard way like I did. Only had to take a smidgen off the bolt too. Just next round you fire try to loosen the screw and see if it frees up the bolt.


Thanks. I had already checked that. It cycles like a dream until I fire it or try to cycle spent cases. Cycles sized case perfect.

[BillPa]

Thanks. I had already checked that. It cycles like a dream until I fire it or try to cycle spent cases. Cycles sized case perfect.


Is the hard extraction lifting the bolt or after the it rotates all the way, but won't move back to extract a case? I assume if you re-chamber a fired case ( not resized) it also extracts hard?

One other thing. Take a look at the casehead(s) of the fired brass and see if there are any rub marks about 25% around midway between the primer pocket and rim, usually right on the headstamp.

I'm just fish'n and trying to eliminate some possibilities. Let me know.

Bill

[rfurman24]

Bolt lift is more difficult than I think it should be but my main concern is actually pulling the bolt back. I do not see anything wrong with the brass maybe slightly more shiny around the primer area.

[dcloco]

Post a picture of some fired brass.

Chamber probably just needs polished.

[BillPa]

Bolt lift is more difficult than I think it should be but my main concern is actually pulling the bolt back. I do not see anything wrong with the brass maybe slightly more shiny around the primer area.


Ok, some more fishing. Using one of the hard extracting pieces of brass place a shim, maybe .005-.010" between the rear baffle and the receiver then try it. Two-three pieces of paper, something on the order of printer paper will work.

What happens then?

[dcloco]

Bolt lift is more difficult than I think it should be but my main concern is actually pulling the bolt back. I do not see anything wrong with the brass maybe slightly more shiny around the primer area.


Ok, some more fishing. Using one of the hard extracting pieces of brass place a shim, maybe .005-.010" between the rear baffle and the receiver then try it. Two-three pieces of paper, something on the order of printer paper will work.

What happens then?




Two or three pieces of scotch tape will work as well.

[rfurman24]

The paper trick did not help. The rear baffle does not even touch the receiver on primary extraction. The brass looks like crap I will have to post pics tomorrow.

[BillPa]

The rear baffle does not even touch the receiver on primary extraction.


Then you have problems!

When the bolt is opened the lug on the bolt handle must contact the cam on the rear baffle otherwise you have zero PE. The baffle may be loose when the bolt is closed, but when its rotated to the open position the lug on the handle will contact the cam, push the baffle forward till it contacts the bridge, the handle contacts the cam and the bolt is forced rearward.

Two conditions can exist, too little of too much PE. Too little means the cartridge will not be pulled free of the chamber, the start of the extraction process making extraction hard. The other, too much and the will lugs will still be engaged while the PE cam is trying to force the bolt back, they're fighting each other.

Actually, there is a third condition, it correct and you have .060-.070" PE

If in fact the baffle isn't contacting the bridge when the bolt is opened there is a problem.

Bill

[rfurman24]

Sorry, Bill, It does make contact will extracting a shell. The tape still does not help.

[Blue Avenger]

any swelling about a 1/2" up from the base?
Found out my 6mm redding die was to large down there. and I have to run my brass through my 7mm rcbs die to size that area until I get a different 6 mm die.

[rfurman24]

I have tried sizing with my 20br and 22br dies. Same problem.

[BillPa]

Sorry, Bill, It does make contact will extracting a shell. The tape still does not help.


Ah.. OK, but another question. You say the bolt rotates all the way open without undue effort, but it tough pulling it back. If thats correct how do you get it open, a bump on the bolt handle, a good sharp smack or a BFH?

Bill

[rfurman24]

Bill, it is more difficult than I feel it should be lifting the bolt at the top but my concern is the difficulty pulling the bolt back. I have to pull very hard to get it back after firing.

[Kawabuggy]

Okay, I have an idea.. Try a different powder with a different load and see if the same condition exists. Post back with your results.

[BillPa]

Bill, it is more difficult than I feel it should be lifting the bolt at the top but my concern is the difficulty pulling the bolt back. I have to pull very hard to get it back after firing.


Well, I dunno. This is what I hate about long distance gunsmith'n. If I had it "in hand" I guess it would take a only few minutes and a beer ( or two) to figure it out. I still think its light on the PE, but without rip'm the barrel off and measuring its only a guess.

Anything else done to that action other than the new pipe?