Carbon on case necks

[hunter24605]

Been getting carbon on the outside of case necks in two different Grendel rifles from different barrel makers. It’s not soot, you really have to scrub to remove it. I know light charges will cause it, but they’re running right at max. I’ve measured fired cases from both rifles and they vary slightly from each other. Both loads use Leverevolution and the same batch of Hornady brass. Has anyone seen this with lever before? Maybe this brass is work hardened and not expanding enough? Might anneal first and see it that works. if not then try different powder..

 

[sako2]

Annealing will help. Are your cases shorter than max length? I get it with other powders when the pressure is low. How close to the lands are you? You might not be at max charge for your gun.

 

[wvbuckbuster]

I don't have this issue with LVR in my 35 rems no matter which brand of brass I've used. Do as you say anneal first and see if that helps. Then try different brass. Hope you get it sorted out. Dan.

 

[hunter24605]

Annealing will help. Are your cases shorter than max length? I get it with other powders when the pressure is low. How close to the lands are you? You might not be at max charge for your gun.

Cases are right at max. I don’t know how far off the lands they are , just set to mag length in AR’s, but consistent with book OAL, so probably a pretty good jump.

 

[sako2]

Have you chronoed the load? My 6.5 prc loads where low on velocity and my necks were dirty. I went a .5gn over max and lengthened the col. The dirt went away.

 

[hunter24605]

Have you chronoed the load? My 6.5 prc loads where low on velocity and my necks were dirty. I went a .5gn over max and lengthened the col. The dirt went away.

Yes, the 123 SST with 31.3 Gr of Lever is running 2526 in the 18" barrel and about 30 fps faster in the 20". So they are stepping along pretty good. I'm working off QL and GRT that was calibrated with my case volume and real world chrono data and both say it's right up against max. There is probably some room on the table, but I've read that gas guns can "mask" early pressure signs. Don't know if there's any truth to that, or not.

 

[RL338]

Maybe this brass is work hardened and not expanding enough? Might anneal first and see it that works.

Here’s where I would start. Have you measured the neck diameter of 1x brass versus brass with multiple firings?

 

[sako2]

Anneal a couple cases and see if it helps.

 

[hunter24605]

Here’s where I would start. Have you measured the neck diameter of 1x brass versus brass with multiple firings?

No, they all have multiple firings and never thought to measure one early on.

 

[sako2]

 

[hunter24605]

Thanks, I like the way this guy breaks things down. I meant to get back to this sooner, but after annealing the Hornady brass they look much better. It was pouring the snow and 10* so I didn’t really see if accuracy changed , just fired off 3 to see if annealing helped. These are once fired post annealing.

 

[sako2]

Looks much better

 

[RL338]

Necks are clean now.