Sooty Fired Cases

[dave from mesa]

Went yesterday and shot my .45 acp Mech-Tech. Noticed that all the cases has quite a bit of soot on them after they were shot.
Not sure why.
Not enough powder? Not enough crimp? Not enough?????
Load is 200gr 200 Grain RNFP coated Missouri Bullet.
4.4gr WST
2.19 oal
WLP primers
Frame is a Para so they are shorter than my 1911 to fit the mag.
any ideas?

thanks

dave

 

[Shaq]

Sometimes caused by a chamber that is out of spec - too large. Brass expands on firing to seal the chamber but if the chamber is too large, it allows blow by (gas & carbon).

 

[scythefwd]

I'd say youre not building enough pressure to seal the chamber correctly. Either a slight bump in charge (keep it reasonable and within published loads.. I dont know your powder or that caliber), or tighten the crimp down a little more. The tighter the crimp, the higher that initial pressure spike due to the slightly delayed release of the bullet, or so I think.

 

[rsrocket1]

Slightly low on the pressure side, but the bottom of the case is not sooty so you are probably sealing off the gases. Did you get a lot of blowback of gas into your face?

If not, you are good to go with that load. You're going to clean the cases anyway so who cares. The Hodgdon site says your load is on the low side of recommeded so if you like it great. If you think it needs more oompf, you have some margin to increase the load.

 

[dave from mesa]

This load is shy of my major PF ipsc loads in my 1911. Thought since they were shorter I would drop the charge down a bit.
No blowback that I noticed.
Will bump the charge up a bit and tighten the crimp a bit and see how that works.

thanks

 

[Blue68f100]

I'm shooting lighter that that on my BE loads, but I have a tight chamber. I would not worry about it if they are accurate and the guns works reliably. May try seating the bullet a little lower will also build up the pressure. Your short of the lube/crimp grove.

 

[LiveLife]

+1.

If you look at the comparison picture of 200 gr SWC and RNFP, RNFP bullet has shorter bullet base length. Using start charge for SWC at similar OAL/COL will result in shallower seated bullet base that will develop less chamber pressure and less efficient powder burn which will result in poor case mouth seal with the chamber and blow by of sooty gas - http://www.hodgdonreloading.com/data/pistol

200 gr LSWC WST COL 1.225" Start 4.4 gr (830 fps) 15,400 PSI - Max 5.1 gr (910 fps) 19,900 PSI

I suggest seating the bullet deeper and/or using more powder. BTW, I use shorter 1.195" OAL with MBC 200 gr RNFP with lower powder charge target loads.

As to taper crimp, more taper crimp does not result in greater neck tension and too much taper crimp can actually decrease neck tension.

If the finished rounds drop in the chamber freely, I would hold off on using more taper crimp as you want the case mouth closer to the chamber to seal high pressure gas/reduce gas blow by. With plated and coated lead bullets, I prefer not to use too much taper crimp which can cut through the plating/coating and expose lead. For .451" diameter bullet, try .473" taper crimp.

.451" (bullet diameter) + .011" (case wall thickness) + .011" = .473" (taper crimp)

 

[Walkalong]

The Mech-Tech is a blow back action. The cases are going to be sooty. Some loads worse than others (Follow advice above.), but all will be at least somewhat sooty.