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pirate357
07-28-2011, 7:02 PM
Hey everyone. I have a newbie question. I'm just starting to reload and was looking through some loading tables, specifically 9mm. Most of the minimum oal were about 1.125. I was wondering how important is it to make sure each round I reload matches these numbers. Is there an acceptable range I can use or should I do my best to match the tables. Thanks.

sequoia_nomad
07-28-2011, 7:28 PM
Keep it over min and you should be fine. 9mm varies quite a bit. I would recommend setting up your seating die with a factory round with the same bullet weight and profile, and start with low charges.

XDRoX
07-28-2011, 7:35 PM
For newbs it's always best to load long as possible. Never load to minimums.

huckberry668
07-28-2011, 9:14 PM
Seating bullets short can cause feeding problems. I found that out the hard way during a match. Load them too short could also cause over-pressure on longer/heavier bullets if you load them hot. Buy a reloading manual and load according to the specified OAL.

waho
07-30-2011, 10:16 AM
Anybody have new edition of the Hornady load book that would be willing to look up the specs for the 124gr bullets? My old version lists a col of 1.050 for an FMJ-FP. That seems really short, not only that, they use the same data for FMJ's and Lead. Does Hornady have a website that gives data? This is for 9mm.

Bill Steele
07-30-2011, 10:22 AM
Anybody have new edition of the Hornady load book that would be willing to look up the specs for the 124gr bullets? My old version lists a col of 1.050 for an FMJ-FP. That seems really short, not only that, they use the same data for FMJ's and Lead. Does Hornady have a website that gives data? This is for 9mm.

Hornaday doesn't have their data online, but many of the powder manufacturers do. What powder are you using?

mkga14
07-30-2011, 10:32 AM
Anybody have new edition of the Hornady load book that would be willing to look up the specs for the 124gr bullets? My old version lists a col of 1.050 for an FMJ-FP. That seems really short, not only that, they use the same data for FMJ's and Lead. Does Hornady have a website that gives data? This is for 9mm.

From the Hornady reloading handbook 8th edition...

#35567 FMJ-FP COL = 1.050"

waho
07-30-2011, 2:45 PM
Yeah, that's still the same. Thanks

Whiterabbit
07-30-2011, 5:55 PM
Fundamentals:

Seating deeper raises pressure. Therefore, it's OK to develop a load seating @ minimum then make some rounds seating longer, but not vice versa.

No max OAL. Just the limits of your magazines, chamber, cycle, etc.

On the same powder charge, seating deeper may or may not change the free-space inside the cartridge. This may or may not be a problem. Consul manual for info if you are thinking about this.

Many resources claim that seating depth is the #2 thing that affects cartridge performance uniformity. If true, then developing a load at min OAL then later seating a longer bullet may change accuracy, POI, or uniformity.

I think that's it for rules-of-thumb?

rsrocket1
07-31-2011, 9:00 AM
What's most important in seating bullets with respect to pressures/velocities is the not OAL, but how much of the bullet is below the case mouth (seat depth). A 124g flat or hollow point will have a shorter OAL than a round nose with the same seating depth. Seating these rounds to the same OAL can result in more than 6,000 psi difference in max pressures (rough QL estimate).

Whiterabbit
07-31-2011, 4:14 PM
I'll take this one step further. I have two loads, they use the same powder, same powder quantity, same bullet weight, same primer, same EVERYTHING, except bullet A is a lead jacketed bullet and bullet B is an all-copper bullet. Both flat bottom spitzer.

I seat both so that the BOTTOM of the bullet is in the same place (as per post #10). pressure should be the same, yes? But POI and group size both (can) dramatically change.

rsrocket1
07-31-2011, 6:52 PM
No, the pressure is not the same. if one bullet is jacketed, the jacket may be of the same density as the all copper bullet, but unless you are very lucky, the over all projectile length will not be the same. Why? The "all copper" bullet is most likely longer then the jacketed bullet because the jacketed bullet has lead in the middle and is more dense. More dense with same weight means shorter projectile length and a smaller length of bullet to engage the rifling. This would mean more pressure needed to push the bullet out and probably different muzzle velocity due to the bullet dragging along the muzzle.

The biggest changes would probably be seen in a rifle where the barrel harmonics change drastically with bullet "time in barrel". I sometimes get groups centered as much as a foot away from a different load @ 100 yards with my .308 and you can not account for that foot by simply saying a different load changes the bullet drop by a foot.

You probably won't see that much of a change with a pistol round. I hardly notice any change in impact point at 10 yards with 45 ACP loads anywhere from 600 fps to 950 fps.

To the OP, I want to emphasize that what you really need to beware of is that you don't overpressure your loads. Getting that extra 50 fps is not worth a blown up gun and an injured hand/face.

Whiterabbit
07-31-2011, 8:10 PM
Funny, there is a MAJOR change to point of impact with the same bullet in my pistol traveling 700 fps vs 1400 fps at LESS than 10 yards.

noylj
07-31-2011, 8:45 PM
I find it is best to learn how to determine the best COL for your gun and each bullet.
The numbers in reloading manuals are either the SAAMI max COL for the industry (so all load to the same or worse requirements) or the minimum they recommend for the bullet.
A reloader should not even need this information, as whenever your start to load a new bullet, you should make up a couple of inert dummy rounds to check functioning.
My very first gun was a Browning HiPower in the mid-70's. I have never had a gun so temperamental in terms of COL. It would feed anything, provided I determine the proper COL. At that time, few manuals even discussed COL as the assumption was that it was a requirement of the reloaded.
I always start out long and work down until feeding and chambering are flawless.
I see too many people today loading to the COL of the manual and, for their action pistol shooting, using bullets too heavy for the cartridge and powder that is too fast. As we all know, there are a goodly number of KBs
nowadays that never happened back when IPSC and the .45 Auto ruled.
A reloader should always find the longest COL and verify no bullet set-back and then work up a load.
Sometimes, I even find that my loads are near the COL in the manuals, but that is the longest COL that works. However, I had already tried longer for that gun.
If there was any "general" rule of COL I would say that 1.260" is a good place to start for .45 Autos, 1.080" for 9x19, 1.250" for .38 Super, and
1.215" for .40S&W. You may need to work down slightly for guns with short chambers. However, everything depends on your gun and the bullet profile.