338 Spectre Cracked Body

[Valornor]

About eight months ago I went on a tour of Southern Ballistic Research (SBR) and discovered a little round called 338 Spectre. I've since gotten a 16" barrel and finally finished the AR build. For those who don't know, this cartridge is based on the 10mm Mag necked down to .338 cal. Similar to 300 AAC Blackout, it was design specifically for launching 300gr SMK's at subsonic velocities. Starline makes the 10mm Mag brass and I use CH4D dies to neck the brass down to .338 cal.

I am still very new to this caliber. I just began working up loads last weekend in three different bullets. I've had some excitement with that (stuck a 285gr Barnes TSX bullet halfway down the bore), despite an obvious squib load, I have not seen obvious signs of over pressure pressure. I.E flattened primers, loose primers, excessive case length growth or ejector marks on the head of the case. QuickLOAD lists the max pressure of 37500 PSI.

As I was cleaning some of the brass I had used to work up these loads I had three cases out of about 30 that had pretty substantial longitudinal cracks on the case body. I've seen small cracks on other cases, usually at the neck or just in front of the head but never anything like this. I can think of maybe one cause, but would like to get input.

My thought is either the chamber is too large and the brass may be too small. Resulting in over expansion of the case and cracks on the body of the case. If this is the case I likely have a chamber that is over sized, and I need to contact SBR. If the brass is to small then fire forming the brass and just doing neck sizing from here on out should prevent the case from expanding more. Unfortunately I do not know what loads produced the cracks in the body, but I will be looking for it in future loads.


These were the first time these shells were loaded after forming.

[Preacher Jim]

Starting at base mic the cases every little bit and record it will tell you die or chamber
Compare to fresh sized case read your results and know

[Dutchninja]

same issue, any additional thoughts? Almost all my cases are splitting. brand new starline brass adjusted sizing die till the bolt closes

[AggieEE]

Looks like defective brass. Almost like the brass was too hard and with the expansion of the first firing it split. That or a weak section of brass. The fracture is so straight it was almost like it was scored. Can you measure the wall thickness around the case, I'm thinking a thin section.

[john.k]

A bit of annealing might help.....Starline brass is said to be left unannealed and hard,to keep prices low.Anneal before neck forming.

[Dutchninja]

Took a look at things last night and got out the hornady comparator just to look at the shoulder of the fired rounds vs what i sized them too. Fired rounds were .963 .965 (ave). originally sized down to .960. Readjusted the sizing die and found they start to stick in the chamber around .971. sized to around .966 and they chambered / extracted in the rifle fine. However, some of the brass if using straight lanolin alcohol mix made sizing ridiculously tough. switched to imperial wax and there was still significant chatter. I had checked the 6.8 forum before getting into any of this and they reported the same problem forming them.

However after looking at some of the cases I sized with the mix the cases formed with a crack in the same location. It was very faint on the out side but you can see a line in the new brass on the inside.

I tore apart the die and there is nothing i can see visually that indicates why it would be doing that. There are hydraulic marks from excessive lube and it did it even with the expander ball taken out. The inside of the die was not rough by any means but i polished up the expander ball and the inside of the die in hoping it would help sizing but still tough as hell.

I'm thinking like John.K, might have to anneal. Even their formed 458 socom is hard to initially size.

Other thoughts?

[upnorthwis]

I would do a chamber cast. If you don't have cerrosafe, you can use candle wax.

[Dutchninja]

Upnorthwis - I don't think it's a chamber issue......yet. not ruling it out. its Tearing the cases before their even shot once.

[Skipper]

I'd contact Starline and see what they have to say about it

Toll Free: 800-280-6660
660-827-6640
info@starlinebrass.com

[DDriller]

All my brass was formed from 6.8 cases and haven't had any issues. My barrel was one of the last few that Marty did before turning it over to SBR. I do have a 1000 with 338 Spectre head stamp from Starline but have never opened the box.

[EDG]

Starline cheaps out by not annealing finished cases.

I think that Starline does not have a good supply of annealing equipment. Starline has only recently began manufacturing bottleneck cases. To easily produce bottleneck brass you need to be able to anneal during the process. Apparently Starline has limited in process annealing capability. The .40-65 Win cases sold by Starline have a fairly high defect rate of 1 to 2 bad cases per 20. This case has a lot of taper and needs in process annealing.

[gwpercle]

Two thoughts:
1.) Anneal the cases before forming.
2.) Use case forming die, not a resizing die, to form the cases with.
This might be a help.
Gary

[popper]

I've had case 40sw split when expanding but it starts at the mouth. I did have some 30/30 with splits at the shoulder and not neck but that was really purchased (won't buy any there again) junk. They also got radial splits around the shoulder. Annealing didn't help. From the pics, you can't anneal that far down safely. If you have 10mm set, try sizing and expanding a few and see if they split?

[P Flados]

If I were in your situation, I would be considering a "base protected by water" anneal.

Take a few cases, set them in a pan with water flush with the solid portion of the base.

Take a torch to the cases and get a good anneal of everything above the waterline. This will be more than a normal anneal, but it should be a one time thing.

Try them and see if it works.