Help with 6.8mm ammo issue on the range

[Nik H]

Hello all,

I will open this conversation by admitting that I am totally new to the 6.8mm world. I got into the 6.8mm world because I wanted something with similar ballistic characteristics to 5.56 but with better terminal effects. I did some research regarding ballistics, suitability for hunting and availability of factory ammunition and determined that the 6.8mm SPC cartridge was an optimal choice.

About 2 months ago I purchased an LWRC M6A1 rifle chambered in 6.8mm. The rifle has been owned by him for 3 years and was never removed from the original packaging. The rifle came with a 14.7" barrel with a pinned and welded flash suppressor to bring it into compliance. Along with the rifle came 1,600 rounds of Silver State Armory 115g OTM ammunition. The ammunition box is marked with the SSA logo and also 6.8 SPC, 115gr OTM, Enhanced fragmentation.

I finally got some free time and went to the range to zero the rifle and optics. After it was zeroed, I fired the remainder of the 20 rounds in the box. No FTF or FTE events occurred. After I gathered the brass, I noticed that 10 of the 20 rounds exhibited cracking in the shoulder area. I enclose a picture to illustrate the problem.

http://i40.photobucket.com/albums/e233/NikH3/Cracked68mmSPCcartridge_zps65b81e6a.jpg

Can anyone give me a little guidance? I understand that different manufacturers use barrels with different chamber specifications (SAAMI vs. SPC II); however, I am in the dark relative to what these mean in practice. Is this round too hot? Is it not suitable for use in an SPC II chamber?

I thank you all in advance for your help.

Nik H

 

[pawprint2]

Have you tried another brand of brass? SSA, has had some problems in their mfg process(s) as of late. It is quite possible their annealing process, was not up to the quality you expect. I suspect you'll not have the problem with any of the Remington offerings.

 

[Nik H]

I did some research and called SSA who is now owned by Nosler. They were very helpful.

It turns out that the ammo in question is a "special" load developed for the military. It is not meant for civilian use. It is loaded hotter and produces much higher pressure than the civilian 115gr OTM round that they sell. It is not designed to be reloaded either. I sent photos of the case heads and primer areas as well. There was no evidence of primer flattening or cratering.

It is fortunate that the LWRC uses an SPCII chamber with a longer freebore area which helps handle the higher pressure.

He suggested that the cracks were "normal" and a consequence of many variables. He did suggest not using this ammo again until it was tested for pressure. They could not comment on how this was loaded as it was manufactured before Nosler took over. He also sent an elaborate report that was done independently. The report showed that this particular load produced a pressure of ~57,000 psi when used in an SPCII chambered 16" barrel.

BR,

 

[EXTREMEPREJUDICE]

So an SSA rep indicated that the cracks were "normal" but suggested not using it until it was checked for "pressure?" I'm sure that doublespeak lets you feel great about the 1600 rounds of ammo you have. I run SSA 6.8 SPC in my Noveske and have never seen that happen. The SPCII chamber is designed for higher pressures and ammo produced for the old/original SPC that has lower pressure can be used with no ill effects (similar to 5.56 and .223.) SAAMI pressure for the 6.8 SPCII is 55K and factory ammo often runs upward to 60K. Not sure about what you're being fed................obviously you won't be reusing that brass.

 

[Nik H]

I hear you....He was a Nosler employee since SSA is no more. I think the "normal" comment and the not fire comment is a CYA.

However, they were at least nice enough to offer to test some samples I have for free along with looking at the spent brass (cracked and non-cracked). I will send some to them.

There are 3 different date codes. I've only tried one. May try firing samples from each of the others to see what happens. If I had seen any damage to the head or primer area, I wouldn't.

BR,