9mm 70 gr pellet vs. 7-ring Jerry Slug – same different ?
Therotically, if we went head to head with a 9mm 70 gr pellet vs. 25 caliber 7-ring 70.2 gr Jerry Slug what differences are we going to see, especailly since the barrel diameters are different ?
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It’s not that easy. You have to have a larger breech because of the larger bore of the barrel. .25 is almost to thin right now at the breech. You also need a larger valve if you want it to be more than an over sized .25. I have a big bore valve and it is massive compared to a condor valve. The tophat is .500 instead of .312. I just had my new .308 and .25 barrels crowned yesterday by Tim at Mac1. I’m ready to go bigbore as soon as I can machine the breech part of my barrel. I don’t trust my little lathe to do it so I will wait a couple more weeks. Need to order up some .308 slugs.
Very good points. Looks like with a 95 gram hammer and standard tank at 3000 psi, one might get only 3 or 4 decent shots with a 9mm barrel. Then again I wonder if even a heavier hammer would be needed. Sure would be nice to have a hog gun by just swapping barrels.
Jerry – you have a good point, I wonder what FPE difference there is. I know frontal area and wound channel account for a whole lot, but I doubt a 7-ring will go all the way through which does leave all the energy disipated inside and possibly a longer wound channel (more vitals hit).
We need a head to head shoot off.
Wait, that doesn’t sound right…
Here is the difference in volumes between a 24″ (610mm) long barrel in .25″ and 9mm
Volume of a cylinder is (pi)r^2xlength
25 caliber: diameter=6.35mm r=3.18mm
(pi)r^2=31.72mm^2 x 610mm= 19349mm^3
9mm caliber: diameter=9mm r=4.5mm
(pi)r^2=63.61mm^2 x 610mm= 38802mm^3
The volume of the 9mm barrel is nearly twice the volume of a 25 cal barrel. The air pressure is pushing against the cross sectional area of the tube at the base of the pellet. The cross sectional area for the 9mm is twice that of the 25cal… You need a lot more air to get the 9mm going and to stay going when compared to the 25 if the projectile weights were the same.
That’s good solid info. I’ll not bother to go 9mm.
Well of the top of my head if the velocity is the same:
Better trajectory with the 25.
Better penetration with the 25.
Better wind resistance with the 25.
More shock on smaller game with the 9mm due to increased frontal area.
Being as it is a sub veloctiy projectile, and the fact that projectile nose design does not influence exterior ballistics with subsonnic projectiles, the blunt nose of Jerry’s slugs vrs a poined 9mm is not an issue, per Dr Mann.
Regards,
Roachcreek
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i have a 9mm 201s and it doesnt shoot worth a shit at 100 yds my 25 will out shoot this POS anyday but i got some new 9mm bullets that might change that results soon to follow