Radius the extractor. How much should be removed?

[jarv442]

Finally got to get out and play with my build. Once I got the whole thing together, while hand "charging", I found that the loaded ammo from Alexander Arms, 120g Nosler BT, were hanging up in the extractor, at first I figured I wasn't giving enough "bump" at the end of the cycle,by hand, since the ammo from Hornady, 123g SST, cycled fine by hand. Next I tried the Hornady 123g SST ammo that I had gotten from Precision Firearms only to find them hanging also but not as tightly as the AA. The AA and PF ammo uses Lapua brass and the Hornady is Hornady brass. The rim thickness is thicker on the Lapua brass, but not thicker than the opening on the mouth of the extractor. I started looking around online to find a solution and saw (http://www.ar15.com/archive/topic.html?b=3&f=121&t=575463) on arfcom and (http://blackholeweaponry.proboards.com/thread/1538/say-goodbye-extractor-separation-issues) here and decider to try to put a little radius on my extractor:




How much more can safely be ground off before the failure to extract comes into play?

While breaking in the barrel(I only got through 35 rounds of the recommended 60)the Hornady and Precision Firearms ammo performed flawlessly!! The AA got stuck in the extractor about every 4 rounds:


This was the first one that got stuck and I thought the empty brass bounced back in off the rest but I moved it so the next bunch wouldn't hit but it jammed again.

Most holes were touching when I wasn't changing settings on the scope. I was getting an average of 2530fps(Hornady),2500fps(AA) and 2440fps(PF) from my 20" barrel, mid length with a Kies adjustable gas block.

I was more concerned with getting the break in done and onto paper so I didn't play with the gas block beyond having it open the initial 1/2 turn. The recoil felt fine and it was throwing the Hornady fine, the PF a little shorter distance and the AA some were just falling out and getting stuck. Next outing I will open the gas block a half turn at a time and see if the AA gets thrown out a little better.

With the bolt out and a loaded round hung in the extractor they all slide in and hold fine, the Hornady falls free once the bolt is turned 180 degrees the PF falls out with a little shake and the AA needs a good shake to fall free. I have 2 extractors and I put a little radius on them both of them. I have 2 springs one with a black bushing(which I was using for the break in) and one with no bushing. Next outing I may try the spring without the bushing.

Before I take any more material off the extractor I want to try it without the bushing under the spring then open the gas block more if I still get the AA hanging up.


Any thoughts and help will be appreciated.

[GLSHOOTER]

At least you were smart enough to do the research!! Kudos!!

Shoot it without the buffer and see how it goes. If not start in and put the radius on there a bit heavier. I believe you won't have much trouble after that.

Greg

[45r]

You might want to try a heavy duty chrome silicon spring.They work a long time and don't usually need anything else like a bushing or little black or blue insert.I debur any possible burrs in the groove with a ruby stone.The inner part of the the extractor groove that pulls the brass should not be dulled by any modification but the back part of the groove  can be radiused.The ejecter can be rounded with a india stone by putting in a drill and spinning the corner against the IS till you get the bevel you want.I polish with a ceramic stone afterwards.I polish the face of the extractor with flits using a bob or felt wheel and everything else that was modified.The corners of the extractor look rounded pretty good.

[jarv442]

Finally got a chance to get back to this. I decided to put a little more radius on my extractors.

I took the sharp corners off on the back side of the two lugs on the bottom, on the carrier side and took the sharp edge off the ejector. 



I cut the sharp edge at the back of the extractor on the bolt and polished the bolt face and all that I had ground.
I put every thing back together without the buffer under the extractor spring, with the Lapua brass the extractor still wants to hold onto the brass, not as hard as before. It just takes a little squeeze on the extractor to let it fall free. The Hornady brass falls free once the bolt gets turned without squeezing at all. 


With everything all together hand cycling, none of the rounds stick at all. I am hoping this is all I need to do to the extractor because I am afraid if I put more of a radius on the extractor I will start to have trouble with the Hornady brass. I hope to get it to run properly with everything but if I have to only use the Hornady brass I'll just stick with that and I may have some Lapus brass to get rid of. 
Here is a shot of it together, I'll get some better pics if I have time when I get to the range.  

[jarv442]

I got out to the range with this to finish breaking in the barrel and test out one of the extractors without the buffer on the spring and it worked flawlessly. I just wish I had thought to change the extractor out and try the other one that I had put a little more radius on, but I was having so much fun I didn't even think about doing that till I got home. I guess I'll have to make another trip to the range. Put around 20 rounds down the tube the first time then finished the procedure this time,the only deviation from the recommended procedure was I cleaned after 1 round, 2 rounds, 3 rounds twice then after 5 till around 60 down the tube then I cleaned after every 10 till I was done. One patch with solvent and two dry and it was squeaky clean every time from beginning to the end I don't think it even needed a break in. I inspected the patches after every time and didn't see any indication of burrs or any metal flakes on them at all. Got it all sighted in. Our Deer season starts this Wednesday, I don't have enough time to work up my own loads for this season but I should have them dialed in for next season or for Yotes after Deer. Lets keep our fingers crossed.
I have a Kies adjustable gas block and have it adjusted out 2.5 turns out from fully closed, up to 2 turns the brass seemed to just fall out, the next half turn did the trick.
I didn't even stop to take better pictures, hopefully I will get some pics with it balanced on some antlers soon.
I want to thank you all for your help on this especially GLSHOOTER, I owe you a beer.

[oldman2]

great info sounds like you have a good answer to the problem..
I wonder how the steel cases will extract , when Wolf finally produces the cheap ammo..

[GLSHOOTER]

Nov 19, 2013 7:04:32 GMT -8 oldman2 said:

great info sounds like you have a good answer to the problem..
I wonder how the steel cases will extract , when Wolf finally produces the cheap ammo..

It would proabably extract fine. I'm pretty sure that I would be foregoing steel and run brass handloads though. Maybe I am too old school but I worry about my chambers getting scored and the expansion/adhesion differential bewteen brass and steel. Of course being a price snob doesn't help either. I like having those newly fired cases to recycle for my next laodins.

greg