RN vs RNFP

[Donny1]

I have been loading extreme copper plated in 9mm.

extreme 124gn RN
CFE Pistol 5gr
OAL 1.125

fps avg is 1125 and functions perfectly over 500 rounds.

I ran out and grabbed a box and didn't realize they are 124gr RNFP (Flat Point). edit: they are just labeled Flat Point, not rnfp

The first round seated much further, 1.060 before I even finished the stroke. Now I need to rethink my OAL but I have no data for these. My RN loads were based on a general consensus of what others were loading, starting on the low end but I can't find anyone loading these.

Any help appreciated.

[croue]

RNFP should seat to a shorter OAL than normal RN.
Does your manual(s) list a length?
Put one of the RNFP bullets next to a RN bullet and measure the length difference.

That may account for all/most of your cartridge length difference right there.


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[croue]

[JagerDog]

1) Compare your remaining case volume to your normal load. (bullet delta vs cartridge OAL delta)

2) Plunk test

3) Test for feeding

[Donny1]

I found one of the old rounds and pulled the bullet, these are .060 shorter. Loading some now minus the difference and they look good, seating depth the same. I'll try them in my new SP101 9mm, shouldn't be a problem it's pretty beefy.

[croue]

[sofbak]

Not sure what you mean by "seating depth the same."

Plunk test one in your barrel before you load a bunch.

[croue]

Seat depth in the case. If the base of the bullet sits at the same position in the case the volume for the powder is unchanged. Pressures should be quite comparable then.


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[sofbak]

^^^Yeah... I tried that once switching fron a rn 230 gr bullet to a truncated cone 225 grain bulletin a match grade 1911. Truncated bullet wouldn't chamber. Hadvto reduce COAL by .015...

Plenty of free volume in OP's cases- plunk test it to be sure

[croue]

I can see how that could happen with those two bullet shapes in 45.


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[pennstater]

OP, how do you like that SP101 in 9mm? Seems like a very nice rig.