Double clicking on extraction

[hendershot]

Hey guys.

So I'm still having problems with case extraction in my Panda. The problem is noticeable after about 10 to 12 firings. At the end of the weekend I can barely extract the case. Needless to say having to pull hard on the bolt handle really upsets a guys rhythm and the rifle in bags! Throughout a two day shoot I will adjust some shims to keep the case sized properly but eventually that doesn't help. I had this problem using a Redding SB die. I then sent a few fired cases to Harrell's and they sent me back a #2.5 die. Same problem. A sized case with the #2.5 die measures the same at the case head as does a fired case I recently realized. Not even .0005" difference from what I can see. Would a #4 Harrell's die be the answer or is that a little to tight?  Thanks, Dan H

[John VM]

 Dan, without having the measurements on the dies and the chamber it is hard to diagnose properly. It does sound like the chamber is to tight for the brass. It is a common misconception that the die sizes the brass all the way down, but it cannot size the part of the casing that is solid brass at the base. Under high pressure loads the base can slowly swell a few thou and if it swells to the point it is tight in the chamber you cannot fix this except to polish out the chamber area to get a little relief.
 When you have a tight piece of brass, measure the base before and after resizing and it does not change. If you measure just above the base before and after resizing, you will see a difference about 1 thou give or take a half thou.
 It is also a good idea to check the new brass when you get it in and check against your chamber dim., the chamber should be 2 -3 thou bigger or it is to tight for your new brass.

[Dwayne Cyr]

Dan

Page 114 of Tony,s "THE BOOK OF RIFLE ACCURACY" gives a good explanation of what is going on. I have 50 tired old cases from my last barrel that I use for practice. When a case starts to click, it gets thrown in the garbage. I hate the disruption of the gun in the bags when you try to lift the bolt.

Good Luck

Dwayne

[Bill Gammon]

When a "LITTLE" bit hard extraction, the brass "GOES"

[hendershot]

Thanks guys for the replies. I will bring my cases to the next match and hopefully be able to try a Harrell's #4 die and see if that helps.

[hendershot]

John...

The base of my new brass measures .0025" smaller than my chamber spec. My chamber specs show a base dia. of .4403, a stiff case measures .4400, after sizing .4400, a once fired case measures .4390. I measured in front of the base on a stiff case getting .4395 with no change after sizing. I did however lock my dial mic at the base of a fired case and after sizing the jaws slid off the end. So it would seem I'm getting a small amount of sizing but not enough? I do not shoot hot loads in my rifle. 28.8g of N133 is where my rifle likes to be which is 52.5 clicks on my Harrell's. I'm typically somewhere between 52.5 and 53.5 and rarely at 54 clicks.

[John VM]

Dan, What is the size of your base on new unfired brass? It is probably close to the once fired brass as it rarely swells much after first fire form. The swelling at the base usually happens slowly for the first 6-8 firings and the the brass work hardens and it settles in. Then it takes some pretty nasty loads to make them swell much after 10 - 12 firings, but nasty is very relevant in this sport as most loads used are over saami spec. Barrels are not always the same and can have significant pressure differences with the same load. 

[hendershot]

John. They measure about .4380 to .4385. About .0015 to .0020 less than my chamber which measures .4403. I re-measured so I'm not sure how I got the original .0025" less than spec as stated in my earlier post. Perhaps I wasn't exact in the placement of my mic.

[cyanchycki]

Dan I am not sure if I told you about my chamber.

I sent Harrel 3 pieces of 3X fired brass.  They sent me a 1.5 die.  Was great for about 5 firings then the click was starting.  Robert told me to call them and ask for a 3.  I thought that may have been to much so I asked for a 2.5.  I could not be happier the entire time I have used that die.

As Jeff mentioned a #4 may be the right die for that barrel if it was cut with Roberts current reamer.  I believe he told me he uses a 4.

Now depending whose reamer you use to cut your next barrels you may not need a 4 but could maybe get away with a 3.  Who evers reamer cuts your chamber find out what die they are using and get the same.

Hope this makes sense and helps.  I am not the book of knowledge like a lot of the shooters are.  I just follow.....

Calvin

 

[John VM]

Dan, I do not remember the exact dimensions that several gunsmiths use but I do know that the dimensions you have in your chamber match what I have in a few of my barrels. They gave me the same grief and other barrels that had been done with a larger reamer had none of these issues. I to did not like going to upper level loads unless i had to and preferred some slow burning 8208 powder, but that did not help with the click and tight brass, it was the chamber.

[hendershot]

Calvin...Acutally that helps a lot. My barrel is currently chambered with Robert's reamer. Strangely enough I ordered the same reamer from PTG as I didn't want to have to buy another die. That was before I was experiencing the problems I'm having now. This double clicking was an issue for me in France as well where I was using a Redding SB die but after Harrell's sent me the #2.5 and I got new brass the problem went away...so I thought. I tried a #4 in France but it didn't help. I'm sure that was because my brass was so hard by the end of the week they couldn't be saved.

I guess I have a few options. Try a #4 at the next match and see what happens, start with new brass and a #4 and see what happens, scrap my brass after 15 firings, or change my reamer order to a different spec to better match my current sizing die. Soon I will have to screw on the two new barrels I have waiting. Thankfully they have not been chambered yet.

[hendershot]

Well I just ordered a #4 die from Harrell's and I didn't even have to use Tom Dickson's name. Hopefully this will solve my problems.