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RCBS 10mm-200-SWC Jammed a P320 .40 S&W
I was pretty surprised to see a 3-point jam in a Sig P320 (4.7 barrel, .40 S&W). The jam happened when I hand racked the slide to load the first round with a RCBS 10mm-200-SWC boolit (50:50 COWW:SOWW +1%Sn + 0.3%Cu). The brass case was deformed when the slide crashed into it. I measured the COAL after the fact and this one was 1.140 (book calls for 1.135). I had 10 rounds in the 14 round magazine, and the next 9 rounds all fed flawlessly. Brass was fired once before, in this same barrel. My next rounds will be 1.130-1.135 OACL, which I hope will fix this problem and meet the front driving band from touching the feed ramp. I cant afford to give up much on the OACL before I run out of case volume with this huge boolit.
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Ill give an update later as I figure out if this boolit will feed reliably or not. Max book velocity is 1,032 fps, so I really want this to work. 15 rounds in .40 S&W that matches .45 ACP energy & momentum is pretty attractive. My velocity at starting charge was 945 fps (True Blue).
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This picture shows where the tip off the boolit and the front driving band hit the feed ramp.
Attachment 315698
This picture shows the damaged brass and boolit, where the slide crashed.
Attachment 315699
3 Attachment(s)
RCBS #10mm-200-SWC vs Saeco 047
My 3rd batch will consist of these two options:
1) RCBS #10mm-200-SWC
a) 1.125” OAL
b) Cast boolit length is 0.717” as-cast (50:50 COWW:SOWW + 1% Sn).
c) 5.7 grains True Blue
Note: GRT says 5.7 grains @ 1.125” gives similar pressure to 5.8 grains @ 1.135”.
2) Saeco 047 200 grain TCBB
a) 1.135” OAL
b) Cast boolit length is 0.702” and weighs right at 200 grains as-cast (COWW + 1% Sn).
c) 6.0 grains True Blue
Note: GRT says the Saeco boolit at 6.0 grains gives similar pressure to the RCBS boolit at 5.8 grains.
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The two reasons for the Saeco boolit are:
1) Smaller meplat, which is good for feeding.
2) TC instead of SWC, so no shoulder to snag on anything while feeding.
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RCBS (1) on left.
Saeco (2) on right.
Attachment 316419
Attachment 316420
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Here is a picture of the 2nd jam, which was not as severe as the first. It does not appear that the ejector claw is grabbing the case rim soon enough. I have had no jamming issues with a 175 grain Lyman #401638 boolit (1.100” OAL), nor 155 grain & 200 grain Hornady XTP (both 1.135” OAL).
Attachment 316421