MG4 and 32 ammo

[jbshooter]

I have been shooting Lapua 98gr from my new MG4. The ejected cases come out covered with slightly oily soot. Does anyone have an explanation for this? Doesn't seem to happen with reloads. The reloads are 1.4 gr 310 and are definitely softer than the lapua factory rounds.

[deadeyedick]

Probably the type of powder used by Lapua that is causing the sooty look, especially if not present with reloads using VV n310.
Factory ammo also uses considerably more powder than 1.4...probably in the region of 1.7 or even a little more.

[Spencer]

...The ejected cases come out covered with slightly oily soot...

Fairly typical of most .32SWL semi-autos: low case pressure and a 'simple' blow-back action gives a fair amount of gas blowing back along the case.
It cleans off easily: I only need to tumble my .32SWL casings in the plastic beads used to sandblast aluminium sheeting.

[morten]

The factory lapua 98gr 32 S&W long ammo, has a velocity of about 240 m/s.
Your 1,4 gr of 310 on the same bullet, gives about 233 m/s according to Lapua's reloading data. So they should be abit softer.

I use 1,5 gr 310, on a 98gr bullet in my MG4, and they feel the same as Lapua factory load. and the accuracy is great.

Still more soot from the MG4 compared to my Hammerli 280 32S&W

[jbshooter]

My thought was that the chamber might be really large, maybe oversize. Or it may have somehting to do with the 150mm barrel.

[deadeyedick]

Some chambers are larger than others for various design requirements and this does result in more blow by, however some powders are dirtier than others compounding the problem. As Spencer mentioned, a quick dose of tumbler solves it until the next time.