I always shoot 115gr at 25 yds and consider to switch to 124gr. Recently bought 2K X-treme 124gr plated bullets to start reloading. Checking the ballistics, I notice 124gr may go thru the transonic at or before 25 yds. For example, American Eagle 124gr shows 1120fps at muzzle and 1078 at 20 yds while speed of sound is also in that range depends on temperature and altitude. Should I avoid shooting 124gr at 25 yds? or I should load light at starting load to keep fps subsonic. Still cycle semi-auto? Now I wonder this may be why my group of 115gr at 50 yds is much worse!
9mm 124gr accuracy at 25 yd?
- Thread starter HankC
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Armed 24/7
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I don't think that it will make one bit of difference. 99.98% of people can't hold the gun still enough to notice.
LiveLife
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I think there are factors that affect flight stability other than transonic bullet wobble. I shoot my 9mm 115/124 gr loads at 25/50+ yards and see round holes on target instead of elongated holes.HankC said:
Hank, since you are reloading consider these variables. 124 gr RN bullets tend to produce greater accuracy than 115 gr RN bullet for these reasons:
- 115 gr RN bullet has shorter base than 124 gr RN to engage the rifling to stabilize the bullet in flight.
- 115 gr RN bullet even when seated deeper around 1.135" has less neck tension than 124 gr RN bullet to require high-to-near max load data to reliably cycle the slides of my Glocks, especially compact/subcompact with stiffer recoil springs.
- 115 gr RN bullet often requires near max load data to produce optimal accuracy with most powders I have used using .355"-.356" groove diameter barrels.
- Many factory barrels have longer leade/freebore and/or larger than .356" groove diameter which allows more leakage of gas that causes chamber pressure drop which results in less consistent muzzle velocities and further aggravates accuracy issues with the 115 gr RN bullet. But loading 115 gr RN bullet longer at 1.160" to reduce gas leakage reduces neck tension that affects initial chamber pressure build, particularly when using less than near max load data.
- 124 gr RN bullet has longer base to engage the rifling and better center-of-gravity for greater rotational stability in flight.
- 124 gr RN bullet can be loaded longer around 1.160" to reduce gas leakage but maintain better neck tension to reliably cycle the slides with mid-to-high range load data while producing accuracy (see 25 yard shot groups with 124 gr bullets below - some elongation of holes are due to indoor range ventilation pushing on the cardboard backing and not bullet wobble as shown on other targets) - http://www.thehighroad.org/showthread.php?p=9924922#post9924922
- To further improve your loads, consider using hollow base bullets with longer base to engage the rifling like Berry's 115/124 gr HBRN thick plated bullets/Winchester 115 gr HB FMJ bullets or larger sized bullets like RMR 115 gr HM RN sized .356" (instead of typical .355") to reduce gas leakage and improve accuracy.
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rodregier
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125g Hornady HAP 9mm projectile when you care to send the very best 
http://www.hornady.com/store/9mm-.356-125-GR-HAP/
http://www.hornady.com/store/9mm-.356-125-GR-HAP/
Sort of depends on how tight a group you can hold and which pistol your shooting (and how tight it will hold)HankC said:
I know a very good shooter who can hold, off a bench/bag, just over an inch at 50 yards with a SIG X-five, but the best after market barrel (Apex Grade) in a M&P9 will only do that at 25 yards...these are both with 124gr bullets
ArchAngelCD
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I think that right there is a good answer. Load the 124/125gr bullet and enjoy...
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