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Sal Picante
07-30-2016, 05:45 PM
Sorry for the cross post, but this is the best guide: http://www.czfirearms.us/index.php?topic=34225.msg189131#msg189131

KG
07-30-2016, 10:08 PM
Thanks Les. Great information. What other factors do you consider if you decide to use a setback greater than .015"? Is .015 just a starting point and adjusted by trial and error?

I'm thinking specifically about 1.10 vs. a longer OAL with the 124 grain Precision Delta load in a Beretta.

Welder
07-30-2016, 11:50 PM
On the linked test, my concern with doing it the way suggested is that if the bullet is engaging the rifling enough to push it back in the case, it may also stick a little (or a lot) in the rifling when you try to pull it back out by the case. If the empty case drops freely in and out of the chamber, the better way to do it would be to install the bullet / case as suggested, then use a small wooden dowel through the bore to gently push the seated bullet/case back out of the chamber. This rifling bullet pull is probably the reason the author feels you need to do this test 10 times with different cases and bullets. If it were me, I would do it once just to get general info on whether I was going to need to be careful about OAL *at all* with this load, and then I would go from there. I'd check my cases with a caliper and choose one of the longest ones for the test, assuming you're going to force it to headspace on the case mouth with the barrel out of the gun vs allowing it to chamber using the slide which may entail headspacing off the breechface / extractor instead.

Anyway, I would be pretty surprised if bullet seating distance from the rifling made an iota's worth of difference in service pistol accuracy at standard game distances. Honestly I would expect more difference to be made by sorting cases by headstamp, or in the case of your Beretta, by slugging the bore and buying bullets that actually fit. I have a Ransom Rest around here somewhere and the OAL thing would make an interesting test at any rate.

Keith, you don't say what Beretta you're using, but I reload for 92's and PX4's. The 92's have a long throat and oversized bores, and you may run up against mag length limitations before you worry about getting into the rifling, especially with short bullets like that. I can load 165 gr Xtreme plated bullets to 1.155 with no issues on touching the rifling on either the 92's or the PX4's. The only reason I don't go longer is that for some reason the Xtremes are somewhat inconsistent in OAL with my setup, so I need to leave tolerance room where they'll still fit in the mags.

In the rotating-barrel PX4's, I have had issues with bullets of certain profiles being loaded too long. Shorten them up to a more 'standard' length and they function fine. The PX4 subcompact, which uses a tilting barrel, fed these same overly-long cartridges with no problem.

Finally, just a note on OAL. I used to load long, reasoning that since 9mm was a high-pressure cartridge, I'd be doing my pistols a favor by reducing internal pressure. I was in a class taught by an instructor that frequents this forum and he was looking at my ammo and commenting on how long it looked. I explained why, and he said he always loaded in the shorter end of the range because higher pressures meant more velocity from a given amount of powder, thus lower recoil due to less powder consumption. I tested this out with my chronograph when I got home and he was right. Bumping my already-loaded rounds down from 1.145" to 1.130" gained about 20 fps avg on the chrono. Not a ton, but significant if you're near PF at your given charge. Obviously this is not a license to Do Stupid Things.

LittleLebowski
07-31-2016, 08:00 AM
Solid discussion, thanks gents.

KG
08-01-2016, 08:22 PM
On the linked test, my concern with doing it the way suggested is that if the bullet is engaging the rifling enough to push it back in the case, it may also stick a little (or a lot) in the rifling when you try to pull it back out by the case. If the empty case drops freely in and out of the chamber, the better way to do it would be to install the bullet / case as suggested, then use a small wooden dowel through the bore to gently push the seated bullet/case back out of the chamber. This rifling bullet pull is probably the reason the author feels you need to do this test 10 times with different cases and bullets. If it were me, I would do it once just to get general info on whether I was going to need to be careful about OAL *at all* with this load, and then I would go from there. I'd check my cases with a caliper and choose one of the longest ones for the test, assuming you're going to force it to headspace on the case mouth with the barrel out of the gun vs allowing it to chamber using the slide which may entail headspacing off the breechface / extractor instead.

Anyway, I would be pretty surprised if bullet seating distance from the rifling made an iota's worth of difference in service pistol accuracy at standard game distances. Honestly I would expect more difference to be made by sorting cases by headstamp, or in the case of your Beretta, by slugging the bore and buying bullets that actually fit. I have a Ransom Rest around here somewhere and the OAL thing would make an interesting test at any rate.

Keith, you don't say what Beretta you're using, but I reload for 92's and PX4's. The 92's have a long throat and oversized bores, and you may run up against mag length limitations before you worry about getting into the rifling, especially with short bullets like that. I can load 165 gr Xtreme plated bullets to 1.155 with no issues on touching the rifling on either the 92's or the PX4's. The only reason I don't go longer is that for some reason the Xtremes are somewhat inconsistent in OAL with my setup, so I need to leave tolerance room where they'll still fit in the mags.

In the rotating-barrel PX4's, I have had issues with bullets of certain profiles being loaded too long. Shorten them up to a more 'standard' length and they function fine. The PX4 subcompact, which uses a tilting barrel, fed these same overly-long cartridges with no problem.

Finally, just a note on OAL. I used to load long, reasoning that since 9mm was a high-pressure cartridge, I'd be doing my pistols a favor by reducing internal pressure. I was in a class taught by an instructor that frequents this forum and he was looking at my ammo and commenting on how long it looked. I explained why, and he said he always loaded in the shorter end of the range because higher pressures meant more velocity from a given amount of powder, thus lower recoil due to less powder consumption. I tested this out with my chronograph when I got home and he was right. Bumping my already-loaded rounds down from 1.145" to 1.130" gained about 20 fps avg on the chrono. Not a ton, but significant if you're near PF at your given charge. Obviously this is not a license to Do Stupid Things.

Great information, thanks. I'm loading for both a 92 and PX4.

Sal Picante
08-02-2016, 11:35 AM
On the linked test, my concern with doing it the way suggested is that if the bullet is engaging the rifling enough to push it back in the case, it may also stick a little (or a lot) in the rifling when you try to pull it back out by the case. If the empty case drops freely in and out of the chamber, the better way to do it would be to install the bullet / case as suggested, then use a small wooden dowel through the bore to gently push the seated bullet/case back out of the chamber. This rifling bullet pull is probably the reason the author feels you need to do this test 10 times with different cases and bullets. If it were me, I would do it once just to get general info on whether I was going to need to be careful about OAL *at all* with this load, and then I would go from there. I'd check my cases with a caliper and choose one of the longest ones for the test, assuming you're going to force it to headspace on the case mouth with the barrel out of the gun vs allowing it to chamber using the slide which may entail headspacing off the breechface / extractor instead.


I use it as a rule of thumb - the test worked well on a CZ where the chamber is really short and the rifling "right there"...
The big take away, when shooting a gun that has a "short" chamber is that sensitive to OAL variation is that you want to establish a good working maximum, do not load longer than this number measurement.

There is some variation when loading mixes brass, so it is good to shorten things up by .02" or whatever.




Anyway, I would be pretty surprised if bullet seating distance from the rifling made an iota's worth of difference in service pistol accuracy at standard game distances. Honestly I would expect more difference to be made by sorting cases by headstamp, or in the case of your Beretta, by slugging the bore and buying bullets that actually fit. I have a Ransom Rest around here somewhere and the OAL thing would make an interesting test at any rate.


Other than velocity changes, which can have an impact on accuracy, I haven't noticed anything... E.g. "Assuming the same velocity, round loaded long vs short do not differ in accuracy"