Ejector swipes

[yoteblaster]

I am loading for the 6.8 SPC and as I am sure you are aware no one published any 6.8 SPC Spec II data that allows you to take advantage of the ability to use hotter loads.

Well I have been reading on the 6.8 forums about loading and watching for pressure signs, one being the ejector swipe.I am not sure what it looks like and how it is created.

 

[Widow maker 223]

Left case at the top. That shiny spot is ejector swipe. This load is warm but not real hot, i dont get swipes on every case. Its caused from higher pressure. This load is a couple tenths above book max and shoots great!

 

[Plant.One]

here's a perfect example of extractor marks on the rim of your brass.

my lr308 is a carbine gas system so way over gassed, and has lock time issues with loads near max. This was actually factory ammo that i thought was a bad lot that hornady had me send back and test based on those photo's.

you can also see the cratering on the primers as well.

that gun is relatively hard on brass, i really do need to put an adjustable gas block on it eventually, or just get a rifle length gas barrel for it

 

[Rich in VA]

Originally Posted By: Plant.One

here's a perfect example of extractor ejector marks on the rim of your brass.

I know you didn't mean that, fixed for clarity.

 

[Squeeze]

One note to make on the 6.8 SPC, is the barrel twist rate, and the chamber specs. First, the re-packaged from 270 Win barrels, 6.8s, with a 1:10 twist barrel, even with the SPC II chamber build up signs of pressure before lets say a 1:11 twist barrel, with a Wyle style chamber(lengthened throat) in the 6.8 SPC. So load data has to be safe in the 1:10 twist barrels, with a any chamber specs.

So if you have a 1:11 or a 1:12 twist 6.8 barrel with a chamber that is friendly to higher power loads, then work up slowly, looking for ejector swips, primer cratering, or even pierced primers. FWIW, I am using RL-7 for 95 gr. Barnes TTSX bullets, and I am getting something north of 2800 fps, with sub-MOA accuracy. My barrel is a ARP 1:11.25 with a DMR chamber, IIRC. I load RL-10x for 90 gr. Sierra and Speer HPs, and 110 gr. VMAX, and 110 gr Sierra SPs, with good velocity and sub-MOA accuracy. If I had to recommend one powder for the 6.8, it would be RL-10x. I get good velocity and accuracy with just about any load combination I work, with RL-10x, in both of my 6.8s.

Squeeze

 

[Squeeze]

Originally Posted By: Plant.One

here's a perfect example of extractor marks on the rim of your brass.

my lr308 is a carbine gas system so way over gassed, and has lock time issues with loads near max. This was actually factory ammo that i thought was a bad lot that hornady had me send back and test based on those photo's.

you can also see the cratering on the primers as well.

that gun is relatively hard on brass, i really do need to put an adjustable gas block on it eventually, or just get a rifle length gas barrel for it

I have a LR-308, that is struggling to find an accurate load, but it isn't showing signs of pressure like yours!

It looks like there is some gas escaping around the primers, too.

For different reasons(mine are accuracy), I think a new barrel is the way I am going to go.

I usually assemble my own AR style rifles, but the price on this DPMS LR-308 was less than I could buy the parts for. So I went that route, and started swapping out stocks, fore ends, fire control groups, etc. to make it mine. After all of the upgrades, it still struggled to shoot consistent groups. So with the new barrel purchase, it will now go down as more expensive than buying the parts.

I trusted DPMS to have a decent barrel on their rifle...Back to buying parts from places that have earned my trust.

Squeeze

 

[Plant.One]

Originally Posted By: Rich in VAOriginally Posted By: Plant.One

here's a perfect example of extractor ejector marks on the rim of your brass.

I know you didn't mean that, fixed for clarity.

truly its both. if you look most of them have marks on both sides of the rim, the round side being the ejector mark and the other being from the extractor.

 

[Plant.One]

Originally Posted By: Squeeze

I have a LR-308, that is struggling to find an accurate load, but it isn't showing signs of pressure like yours!

It looks like there is some gas escaping around the primers, too.


Squeeze

those were factory loads, Hornady match. most of it is because the bolt is moving too early before the chamber pressure has fallen and the brass has shrunk back down again. At least thats what we were able to determine in talking with the nice folks over at hornady who tested the ammo they had me send back (everything i had with that lot number) and they all came in under pressure. After lots of other research i'm just simply over gassed to all [beeep]. So while i'm chasing a bughole load with this rifle - my biggest desire to upgrade the barrel is simply for wanting to make it easier to work around the gas issues inherent to the platform i'm working with at the moment. And i'm sure accuracy will improve as well with a higher grade barrel strapped into it.

like you i picked mine up because i couldn't build one for what i paid for it originally.

mine will shoot Sub-MOA with the factory barrel with handloads - i can get it down into the .6xx's and it runs FGGM with the 168 SMK's at MOA pretty consistently - at least if the idiot behind the trigger is doing his job properly

.

here's a group i shot at 565 yds with 168 amax match on the same gun a couple summers ago (we had corn on the big field last year so no joy on my long range.) even totally owning the flyer - i totally pulled the shot and called it at the time - it was still pretty decent for just dabbling in long range shooting. without the flyer its nothing short of spectacular though for a 16" carbine with only a trigger job & ff handguard.

w/ flyer measured in

throwing out the flyer