6.5x55 sooty cases.

[deadcenter]

I know this has been beaten to death all over the web, but I'm having an odd problem with my 6.5x55.

Rifle is a Tikka M695 varmint, 24 inch barrel. 

My loads started with new Lapua brass, 139gr Scenars and Vhit N160, Fed 210 primers.

Started around 39gr and worked up to seemed like maximum for this gun - 44.5gr, started to get stiff bolt lift and flat primers. This is around the max in the vhit Skan load data also.

Thing is after 42gr the cases started sooting along their length right up to the max I tried.

41.5gr hit an accuracy node, less than 1 moa, which I'm ok with, but only chrono'd at around 2300fps which seemed slow.

Didn't chrono the max load so don't know what it went to (Doh!)

I found it odd for the cases to soot as the load increased.

I need more velocity than this for 1000 yards at bisley and wondered how to cure the sooting or if I should even be worrying about it?

Want to stick with N160 if I can as I have a fair bit of it.

Open to suggestions.

[Popsbengo]

Your MV is low for the charge weight and the sooting is indicative of a failure to effectively obturate.  This suggests to me that you're starting pressure is too low and failing to get a complete burn. 

Poor obturation means high pressure gas is coming back down the chamber and that's not something you want to ignore.

N160 seems a tad slow for a 139.

I’ve run your load through Quickload and 44 gr N160 is right on the limit at 2726fps.  Your 41.5gr load is calculated as OK with 2589fps.  I’ve used standard SAAMI data for dimensions and a 24” barrel

N555 45gr is close to max pressure but gives 2698 fps

N150 is too fast according to QL

[deadcenter]

It is possible the magnetospeed is acting up. Waiting gor a new unit for it.

Just a bit confused as to why the soot starts as the powder weight increases.

Thanks for running that though quick load. It's more the velocity I was expecting to be honest.