Dasher Split Necks (Please Help)

[Subsilent22]

Well I just got back from a 600 yard F-class match yesterday in which I shot my new 6 Dasher in. I have been playing with some fire forming loads here at the house using the false shoulder method, after adjusting the load I was consistently getting decent blow lengths and pretty good accuracy. Also every piece of brass came out well formed without any splits on the shoulders or necks. The brass I used here at home I annealed on my bench-source after creating my false shoulder. I have been waiting for this match to come up so that I could fire-form and compete at the same time thus giving me my new match brass. Well I loaded everything the same as before except I decided not to anneal the 70 rounds that went to the match with me. The ammo shot as good as I could have asked for: 594-24X with a brand new setup: from front rest to gun to rear bag, all first time out at a match. So I am happy with the results for now but when I got home I started to inspect my brass as usual and out of 69 pieces of new brass 50 have very very faint hairline cracks in the shoulder. The cracks are so small I had to pull out a magnifying glass to look at them and determine weather they were cracks or just scratches. After inspecting them I do believe they are cracks however I can not feel them on the inside with a dental pick nor can I get my fingernail or dental pick to catch on all of them on the outside. I wonder if they are just stress cracks that don't follow all the way threw to the inside? What are the chances if I annealed these and then fired them that they would seal up the crack? That may be a crazy question but dang Im pretty upset that it appears that I have wasted 50 brand new pieces of brass!! FYI I have spent more money and time trying to figure out the Dasher than I ever thought possible, Hence the name of the gun thats printed across my mirage shield (DAMN DASHER)

Thanks for all help in advance!

 

[Phil]

A gentleman here, that has been EXTREMELY helpful with my set up, has told me to anneal every piece of brass new or not especially when fire forming.

Seems to me that it is just a necessary step....

I quit having splits after I started annealing before fire forming, as you did....

The Dasher is awesome, you just have to learn it`s habits...

Good luck with your rifle..

 

[SDDasher]

James
What was your load to fire form and did you Jam your bullets? I have never seen Hairline cracks while fire forming Dasher brass. The split neck/shoulder is usually very easy to identify. Like Phil, I anneal before fire forming and loose one on a rare occasion. Before you pitch the brass have Alton or someone with equal expertise take a look at it and advise. That was some incredible shooting with new brass being fire formed.

 

[Subsilent22]

I had 31.5g of Varget, 450's and 105 Berger BT set 10 thou in the lands, false shoulder set with firing pin out and the bolt handle would drop about a quarter of the way down before I had to close it the rest of the way with medium resistance. I am going to take the brass to Alton tomorrow and let him take a look at it. In the mean time I wandered what everyone on here might have to say. Thank you Mr. Wes, those kind words mean a whole lot coming from a man with your talents!!

 

[dkhunt14]

I believe that's a lot of Varget to fireform with. Especially if you have a slow tight barrel. I have .155 freebore and form with 30 grains. Matt

 

[CaptainMal]

Without seeing it but listening to your description - carbon blow by???

Varget is dirty and deposits lots of carbon. During fireforming it might be more prone to allow some "blowback" during shoulder formation. That could end up as a hard deposit randomly "baked" into the shoulder.

Simple idea to see. Polish the shoulders where those marks are. Use CR4 carbon cleaner, Iosso or just plain buff/steel wool clean. Then you should see if they really are cracks or just discoloration/carbon.

I use 4895 and jamming to fireform.

 

[johara1]

I see from your statement that you get decent acc. while fire forming ……. That was a mistake, Anneal first, clean and dry the chamber with non chlorinated brake cleaner. I only use 30.2 gr. of Varget with a federal primer plus seat the bullets in .020.
What neck do you have? see if there is a crease inside the case before you load. If you let it get hot and dirty they will be short. I fire 5 and clean the chamber…….. PM me if you need more info……. jim

 

[Subsilent22]

I have polished the shoulders to see exactly what I had and there is something there. A line is my best decryption, i have tried taking pictures but it won't show up they are so small. I let my wife try to find them and it took about 5 min before she spotted it on one. The line as I will call it looks like a eyelash fell onto the case but is much smaller in width and length. They are in different locations on each case and different sizes, the longest is about .080 and the shortest is .030. Some run from about a 1/16 before the shoulder body junction to the junction and stop, some run from above the shoulder body junction to below the shoulder body junction and some run just in the middle of the shoulder. None run to the neck shoulder junction or even close to it, they are right above the new shoulder body junction. The reason I am using 31.5g of Varget is because I ran 30g-33.9 looking for a good blow length and I found that 31.5 gave me the best blow length with out hammering the cases too hard (or so I thought) Higher loads did the same length up until the real high loads they actually got shorter again. At first I was really concerned with blow length and maybe I shouldn't have been. My first impression of the lines were stress cracks, but after investigating Im really not sure now. You can get your fingernail to catch on some, you have to run you nail at the right angle and over it a few times though. But nothing can be detected from the inside. I think Im going to cut one open, polish the inside and see what I find.

Oh and the barrel is a Kreiger .236 7.5 twist

 

[Subsilent22]

Well Gents, I think we have it figured out. I took all the brass that I suspected had cracks to Alton Britt (owner of Dixie Precision) who I would consider a professional, after examining the brass a conclusion was reached. It appears that there are either chatter marks in my chamber from being reamed or like someone mentioned a bristle had been left in there from a brush. To verify that they are not cracks I took the worst 6 cases and full length sized them multiple times, intentionally over sizing them to see if the cracks opened up, they did not change. I also cut one up from a suggestion I received on here and put the piece in a vice, indicating the crack in the middle, screwed the vice together to crush the brass and see if the crack opened up or the brass folded in that spot, it did not. So it appears I'm in the clear. I just want to say thank you to all that replied and gave advice, I took all advice and used parts of everyone thoughts to reach the conclusion that I have reached. Thanks again and keep me in the X ring!