Could FMJ-FN vs FMJ-RN really cause all this?

SuperTrooper

SuperTrooper

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On one of my 4th of July sales I neglected to notice that the Winchester Target & Practice 9 mm 115gr FMJ rounds in the order weren't the usual RN that I usually order, but were instead FMJ-FN (flat nose). With them today I experienced malfunctions, many malfunctions. My stone reliable P320 AXG Legion today threw a dozen or more live round stovepipes, and my P365 X-Macro locked the slide open after each and every round. When I switched back to my usual RN 115gr FMJ they both returned to their regular flawless operation, as with my 127gr poly reloads. I do see these FN are significantly shorter OAL than all my other rounds. Could the difference in shape, or OAL really cause all this, or did I get 250 bad rounds? I've never seen these short Winchester 115gr FMJ-FN rounds before - what are they for?
 
MisterEd said:
Range practice, target shooting, plinking etc.

The flat nose cuts cleaner perforations in paper targets, making hits easier to see at a distance.

You didn't get 250 'bad rounds'. I'd say your guns simply do not 'like' the shorter, FN bullets.
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My chronograph shows over 600 fps in variations. 6 pistols, none would digest them, are they for a revolver?
 
SuperTrooper said:
are they for a revolver?
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Well, no 9mm ammo is specifically designated for a revolver so maybe it is just crappy ammo with a wide variation in powder charges. 600 FPS seems pretty excessive but I guess it's a possibility.

I haven't bought any commercial ammo in probably 15 years, and that was just one box of .30-30 to go shoot a Mod 94 I had just traded for.

I reload everything (and coming up soon on 50 years of doing so!) so I haven't ever had the experience of 'bad' ammo.
 
My reloads are usually within 10-15 fps, I hear you. I just got one of those radar chronograph deals that records everything, I'm still pooring through the session data, but it appears that the only thing that looks amiss are the 115gr FMJ-FP.... Many were under 1000fps, way under.
 
9mm ammo in general typically has a fairly narrow range of FPS (both factory and load data) from the upper 800's to low 1000s.

Anything slower and and it's not going to cycle properly or consistently. Most 'modern' 9mm guns are rated for + P loads and tend to like a little 'hotter' ammo.

There are low .45 ACP loads in the mid 700's but most quality 1911s can be 'tweaked' fairly easily to easily handle lower velocity loads.

Heck I have a bunch of .45 ACP I have reloaded in picked up aluminum cases for one time, let 'em fly plinker field loads I don't have to pick up. These are loaded with 200 grain LRN bullets with 3.5 grains of bullseye and they actually cycle in my Colt 1911 WITH an 18 LB recoil spring I recently installed! The cases barely roll out of the gun but they actually cycle.

And with regard to reloading aluminum cases. I have taken a LOT of chit from people about it (probably those who don't even reload) but loaded ONE time, with low velocity reloads for throw a ways it is just FINE. I've been doing it over 30 years (when I can find enough range pickup alum cases !)
 

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