Case Head Separation

[crystalgayleguy]

check the headspace

 

[Dr. Richard Gray]

I was doing some load development this morning with my T/C Encore 22-250AI and had my first case separation in over 35 years of reloading. Brass was twice fired Lapua 22-250 Rem. Load was 40.0 grains of a Varget which Nosler lists as their max load for a 52 grain bullet. I worked up to this load starting at 37.0 grains and saw no pressure signs. Speed was 3,983 from a 26" barrel. Brass was annealed and full length resized with .002 shoulder setback. I checked the remaining brass with a paper clip and felt nothing inside the case that would indicate this is anything other than an isolated instance. Interested in your thoughts. View attachment 203817

I just looked at your reload info and Nosler load-data is showing a max charge for 50-55 grain bullet as 36 gr. I use the load-data.nosler.com web site. You might want to recheck your information on your max charge. Putting that aside, I did have a separation with a 5.56 cartridge that was once fired. This was Winchester cartridges. I had to disassemble the rifle to get the cartridge out of the chamber. Did you have a problem with that? If so I used some WD 40 and sprayed it into the chamber and let it set for about 30 minutes. Then with another fired cartridge I first cut the cartridge in half, then got a drill bit that would fit tight inside the cartridge and not cut through the casing and gave it a couple of twist with a pair of pliers and pulled the cartridge out. What your showing in your photos is exactly what mine looked like. Mine was well within the specs, a couple of grains below max. My solution was simple. It cost as much or more to reload .223 or 5.56 (50-50gr ) than you can buy them on sale from MidwayUSA ($0.42/ round) when they have free shipping. The only time you can save on that cartridge is if it is one of the heavier loads (75-80 gr). My cost for a 55 gr reload is about $0.33/ round (less brass) if you include the cost of brass it is well over that. I understand that you sound a lot like me, reloading for 50 years, like to do it, work up special loads, etc. etc. But, at 71 years old I look more at the cost and savings now. I have a constructed spreadsheet for all of my calibers of rifles and pistols that will give me the exact cost at any time in history. The real savings in reloading come in your large calibers, like my Weatherby .340 and Ruger .375. When you get below the .243 caliber it is almost not worth reloading.

 

[antelopedundee]

It is obvious from the soot on the shoulder that the case never sealed in the chamber. The brass split well forward from where normal case head separation occurs but others have stated pretty much the same thing. My one additional comment is make sure you check the chamber where the separation occured with a bore scope. If the hot gases pitted the chamber or ringed it, you'll have to set the barrel back and rechamber to eliminate the future compromise of your brass. Future firings in a damaged chamber will cause the brass to flow into the pit or ring and eventually ruin any brass that did not split. I had a similiar problem with a 270 Win and while searching for a solution, ruined the chamber. It only took 3 additional test firings to ring the chamber! SO, be careful. My gun is back at the smiths to correct the problem. Good Luck!

He is shooting a T/C Encore and not a bolt action. I don't think it would be cost effective to fiddle with rechambering it. Maybe send it to some place like SSK.

 

[antelopedundee]

Here's one more vote in favor of the "false shoulder" fire-forming method. My reason why is that when just using the bullet jammed into the rifling, you are dependent on neck tension to hold everything tight against the breech face. Maybe that one ( and possibly others in the lot ) was a little loose. The false shoulder that all the other guys mentioned has worked very well for me with the 30-06 AI, but in a bolt gun. It might be a bit of a chore to close the breech on your gun multiple times with the crush fit you'll be getting with the secondary shoulder. Some rubber grip work gloves may be helpful. Good luck, and let us all know how it works out for you.

All well and good, but it's best if you neck size only until the cases won't chamber properly.

 

[just_jon]

Checked headspace using Mike Bellm's method and found the following:
Barrel to frame gap: 0.003"
Case head (FL sized) to firing pin bushing with extractor removed: 0.005"
Total headspace: 0.008"

Mike recommends total headspace of 0.001" to 0.003", so I ordered one of his shim kits. Next step Is to check the action on other barrels as I expect shimming of the firing pin bushing will require some compromise. I could potentially shim to 0.001" total headspace and does not cause lock up issues on other barrels. May have to pick up another action. I have been considering doing so for some time to have a lighter trigger on my varmint calibers.

I have a Redding 22-250AI neck sizing die, but everything I've read over the last 30 years recommends full length sizing the Encore and Contender to ensure a safe lock up. Now that I think of it, I neck sized my very first batch of R-P brass for this barrel and had no issues with lock up or case separation even when I was running 52 grain SMKs in excess of 4100 fps using N140. The only reason I stopped using that brass after 8 firings was because they had become severely corroded from being stored in a damp basement.

The front end of the case came out easily. I bore scoped the chamber and saw no damage. I will make a chamber cast to double check things and to establish a baseline for future load work.

 

[just_jon]

forgive the errant attachment.

 

[montana west]

P O ackley sholder is 40* your brass is 25* thus only the very front of the sholder is secure in the chamber. if the case is not very tight it will cause problems.. as you know.. again I feel you just need to adjust your dies and seat the bullet out to contact the rifles for the first firing, using the starting load of a faster powder and the heavest bullet you can get.. IN a way in the end you will like the chamber because you will always have a little less pressure and for sure it will be more accurate.

 

[Huntz]

Checked headspace using Mike Bellm's method and found the following:
Barrel to frame gap: 0.003"
Case head (FL sized) to firing pin bushing with extractor removed: 0.005"
Total headspace: 0.008"

Mike recommends total headspace of 0.001" to 0.003", so I ordered one of his shim kits. Next step Is to check the action on other barrels as I expect shimming of the firing pin bushing will require some compromise. I could potentially shim to 0.001" total headspace and does not cause lock up issues on other barrels. May have to pick up another action. I have been considering doing so for some time to have a lighter trigger on my varmint calibers.

I have a Redding 22-250AI neck sizing die, but everything I've read over the last 30 years recommends full length sizing the Encore and Contender to ensure a safe lock up. Now that I think of it, I neck sized my very first batch of R-P brass for this barrel and had no issues with lock up or case separation even when I was running 52 grain SMKs in excess of 4100 fps using N140. The only reason I stopped using that brass after 8 firings was because they had become severely corroded from being stored in a damp basement.

The front end of the case came out easily. I bore scoped the chamber and saw no damage. I will make a chamber cast to double check things and to establish a baseline for future load work.

Some thing else worth while doing is adding one of Mikes extra power Bolt lock springs and either an oversized hinge pin or and adjustable hinge pin from EA Brown.

 

[just_jon]

Some thing else worth while doing is adding one of Mikes extra power Bolt lock springs and either an oversized hinge pin or and adjustable hinge pin from EA Brown.

Currently running a oversize (1X) hinge pin. I just checked out the HD bolt lock spring on Mike's website and placed an order for each of my barrels. He makes a compelling argument that the upgrading the spring when using an oversized hinge pin. Thanks for the tip.

 

[Just ken]

In addition, looks like your fireform load was too hot, should be using a light load for standard 22-250, not 22-250AI

 

[antelopedundee]

I was advised to use stout loads with the bullet jammed when fire forming AI cases. Has not failed me yet.

OMMV!

 

[just_jon]

In addition, looks like your fireform load was too hot, should be using a light load for standard 22-250, not 22-250AI

Agree 100%. FUBAR from the start. This experience has me second guessing myself at the bench. Not necessarily a bad thing. I found my notes from the first batch of brass I fire formed for this rifle In 1993. I used 12.3 grains of Green Dot and a 52 gain SMK seated well short of the lands at 2.35". Worked perfectly, so the plan this time around is to go with the same powder charge of Green Dot, but with 80 grain ELDM 2nds jammed into the lands for some extra insurance.