School me on OAL

[dukeguy]

I'm a newcomer to reloading and have been reading everything, everywhere about various loads and combinations. One thing I can't figure out is how to determine the "best" OAL. One writer says to use the longest OAL possible, while another lists very short OAL's. Then there are those who say you just have to find the "best" OAL for your particular gun, while another said he called the bullet manufacturer to get their recommended OAL.

So....how do YOU go about determining the OAL for your loads? I'm currently using Precision Delta 124 FMJ's and Montana Gold 115 FMJ's. Powder is either Titegroup or 231.

[Red Ryder]

Good luck!

[mda]

I'm a newcomer to reloading and have been reading everything, everywhere about various loads and combinations. One thing I can't figure out is how to determine the "best" OAL. One writer says to use the longest OAL possible, while another lists very short OAL's. Then there are those who say you just have to find the "best" OAL for your particular gun, while another said he called the bullet manufacturer to get their recommended OAL.

So....how do YOU go about determining the OAL for your loads? I'm currently using Precision Delta 124 FMJ's and Montana Gold 115 FMJ's. Powder is either Titegroup or 231.

What cartridge? 9mm luger, 38 special, 9mm major, 38 super? What type of gun glock, STI/SVI, CZ?? There will generally be a range of OAL that will work in a particular gun make, but it is best to test a number of different OAL with in that range and see what is best for your gun.

MDA

[Alan550]

After I find a load that makes power factor with the preferred powder, I play with the OAL in increments of .005" starting long and working down to shorter lengths, checking for accuracy & velocity as I go. It's amazing how much difference just that .005" difference can make in group size, and velocity changes. You didn't mention caliber, so I won't specify the OAL I'm using. It's all trial & error until you find what works best for your purposes, whether you're after accuracy, velocity or a combination of the two.

Alan~^~

BTW, RR, that was a really helpful response!!

[Bike Effects]

It appears the gentleman is shooting a 9mm, or am I missing something?

[gng4life]

There are several ways people go about it but the best one, especially if you are new, is go by the reloading manual. Every load in every book I've ever seen had the OAL listed. The second best way is by word-of-mouth of the posters here on this forum and others. Most come here with tons of experience and that experience will help shorten your search for "the perfect load".

There is tons of info on the forum, here are a few that are easily searchable:

http://www.brianenos.com/forums/index.php?showtopic=115199&st=0&p=1306792&hl=+determine%20+oal%20&fromsearch=1entry1306792

http://www.brianenos.com/forums/index.php?showtopic=112185&st=0&p=1273635&hl=+determine%20+oal%20&fromsearch=1entry1273635

http://www.brianenos.com/forums/index.php?showtopic=102451&st=0&p=1166809&hl=+determine%20+oal%20&fromsearch=1entry1166809

http://www.brianenos.com/forums/index.php?showtopic=101345&st=0&p=1155948&hl=+determine%20+oal%20&fromsearch=1entry1155948

Good luck...

[superdude]

there are two basic considerations for oal length in semi-automatic pistols. 1) reliable feeding. 2) fit in magazine and chamber. these vary as a function of gun design and bullet nose design.

beyond that is accuracy. that is a bit harder to determine and requires trial and error. most people find that flat nose bullets tend to shoot more accurately than round nose bullets in handguns. this is often blamed on weight distribution. flat nose bullets tend to have a higher weight ratio in the bullet shank, as opposed to the bullet nose. some folks claim this gives the bullet better stability in flight.

a potentially useful source of information: http://www.38super.net/Pages/Bullet%20Design%20and%20Feeding%20Reliability.html

[dukeguy]

Thanks for the responses and suggested links. Unfortunately, I've read most if not all of them. Hence, my search for more info. I guess the thing that is puzzling me most is the discrepancy in the information. As I said, one says to load as long as possible, while another says load short. For example, the Lyman's Handbook lists a maximum length of 1.169 for a 9mm, yet suggested OAL for a 115 gr. is 1.090. For 124 gr. it is 1.075. Many of the loads I've copied from experienced reloaders seem to hang around the 1.135 mark. Is there any particular reason?

And yes, I am talking 9mm, primarily from a Glock 19.

Thanks again for the responses!

[Mark R]

When I load for my Para P16 in 40 cal...I load out to 1.180" OAL. The Para Ordnance and STi/SVi guns like the long OAL for reliability of feeding.

I can't load those rounds in a Glock magazine...they just won't fit in the mags. So when I load for Glock in .40 cal which requires a shorter OAL...I go with 1.130" OAL and adjust powder charge, powder brand, and bullet weight to reach my PF goals.

So, it really depends on what platform you are shooting out of...then go from there for reloading purposes. Hope it helps clear the mud.

Edited July 25, 2011 by Mark R

[superdude]

Thanks for the responses and suggested links. Unfortunately, I've read most if not all of them. Hence, my search for more info. I guess the thing that is puzzling me most is the discrepancy in the information. As I said, one says to load as long as possible, while another says load short. For example, the Lyman's Handbook lists a maximum length of 1.169 for a 9mm, yet suggested OAL for a 115 gr. is 1.090. For 124 gr. it is 1.075. Many of the loads I've copied from experienced reloaders seem to hang around the 1.135 mark. Is there any particular reason?

And yes, I am talking 9mm, primarily from a Glock 19.

Thanks again for the responses!

the difference might simply be because they are talking about different bullets. i'm looking at my Lyman book and see the same numbers you quote. the 124 grain bullet has a shorter nose, therefore it has to be seated deeper or it won't fit in chamber at the same oal as a bullet with a longer nose, like the pic of the 115 grain bullet. its just that simple. the cartridge has to fit in the chamber. if the bullet has a short nose, the oal will be shorter (assuming you're loading them to the max overall length that will fit in the chamber). see Figure 14 of the link i pointed out above. in that figure the bullets were loaded to the maximum length that would fit in the chamber of that barrel. note that the oal is different for every bullet, and note also that the length of the bullet nose is different for every bullet. bullet nose length matters, which is why it is emphasized in Figure 5 of that link. see figure 13 of that article for an explanation for fitting in the chamber.

you can't just load all bullets to the same overall length. life isn't that simple. there are reasons why loading manuals give different oal for different bullets. i mentioned the basics in my first post - reliability and fit. this applies to all handguns and oal can vary with EACH bullet design.

overall length can dramatically affect feeding reliability. some guns don't like cartridges with a short overall length. they won't feed them. but it varies as a function of gun design.

oal also affects pressure. the deeper you load the bullet, the greater the pressure. ALWAYS follow the guideline of the reloading manual, and if you have to load deeper than the manual says, back off on the powder charge.

its good that you're paying attention to the overall length numbers. it will help you load SAFE and reliable ammo. always pay close attention to it.

if you want oal information in nauseating detail, see: http://www.38super.net/Pages/Overall%20Length.html

Edited July 25, 2011 by superdude

[Red Ryder]

After I find a load that makes power factor with the preferred powder, I play with the OAL in increments of .005" starting long and working down to shorter lengths, checking for accuracy & velocity as I go. It's amazing how much difference just that .005" difference can make in group size, and velocity changes. You didn't mention caliber, so I won't specify the OAL I'm using. It's all trial & error until you find what works best for your purposes, whether you're after accuracy, velocity or a combination of the two.

Alan~^~

BTW, RR, that was a really helpful response!!

I'm still trying to find my "best COAL", been loading for 6 months.

[dukeguy]

Again, thanks for the responses. It's beginning to make more sense. And superdude, you're right. The detail on the super 38 page is nauseating, but good!

[1SOW]

I'm a newcomer to reloading and have been reading everything, everywhere about various loads and combinations. One thing I can't figure out is how to determine the "best" OAL. One writer says to use the longest OAL possible, while another lists very short OAL's. Then there are those who say you just have to find the "best" OAL for your particular gun, while another said he called the bullet manufacturer to get their recommended OAL.

So....how do YOU go about determining the OAL for your loads? I'm currently using Precision Delta 124 FMJ's and Montana Gold 115 FMJ's. Powder is either Titegroup or 231.

You didn't mention what pistol you shoot.

1.Determine the MAX OAL your chamber will accept for each "different brand or nose type" of bullet you use using the "dummy round drop in test". Most 9mm service pistols will accept the Saami max 1.169". for most FMJrn bullets. Switching to a flat tip, conical nose, or hollowpoint will usually require a much shorter oal to fully chamber on the case mouth and NOT have the bullet contact the rifling or chamber cone. EG.: 9mm CZ and XD will usually require a shorter oal than Glock--especially for bullet nose shapes other than rn.

So let's say the drop-in test for your pistol chamber with your bullet choice will eccept the PD 124fmj at 1.21". Magazines will only run 1.169", so up to 1.169" length should run in your pistol. Next go to your reloading manual/published data.

2. Your reloading manual may give a load at a 1.145" oal. That tells you an OAL 1.145" OR LONGER will operate at safe pressures with the powder and load listed. If your pistol will chamber 1.145" then you're good-to-go. If it won't chamber that length with that bullet, then you will need to use LESS powder than the manual shows at a shorter oal, working up slowly from a lighter charge.

3. Changing the oal shorter or longer (with appropriate powder changes) can often effect accuracy. Sometimes not so much. Some reloaders will load shorter just to save powder if the load still works well. Win 231 in 9mm will 'often' run nicely with 124gr fmj bullets at 1.13"-1.135"-ish

Experimenting with safe published data can find that accurate and clean load for 'your pistol and 'your bullet choice at the speed/power factor 'you' want to run.

Hope this makes sense.

Edited July 25, 2011 by 1SOW

[twodownzero]

The book length is NOT the "recommended" length. It is the minimum length that a particular book load is safe at. Most of the time it is FAR shorter than you'd ever load.

[soundwave]

Hi Duke,

For my Glock 9mm's (including a G19) I have found my OAL sweet spot to be right around 1.140". I am using 124gr MGB over Titegroup as well.

That said, I have loaded out to 1.160" with no problems in my 9mm Glocks also. 1.140" just puts me at a good power factor and works 100% in my guns.

[Steve RA]

The easiest way to get the proper OAL for any load/bullet is to take the barrel (out of gun) and drop a loaded round into the chamber, if it goes in freely and stops with the base of the case even with the barrel hood (or whatever passes for a barrel hood on whatever gun you are checking) then that is the correct OAL for that load/bullet in that particular gun.

[TGriff]

The easiest way to get the proper OAL for any load/bullet is to take the barrel (out of gun) and drop a loaded round into the chamber, if it goes in freely and stops with the base of the case even with the barrel hood (or whatever passes for a barrel hood on whatever gun you are checking) then that is the correct OAL for that load/bullet in that particular gun.

Someone can correct me if I'm wrong but most auto cartridges headspace on the mouth of the case and would stop at the same point in the barrel until the COL is long enough for the bullet to start engaging the rifling. This means that dangerously short COLs would still drop to the same depth in the chamber as safe ones.

[twodownzero]

The easiest way to get the proper OAL for any load/bullet is to take the barrel (out of gun) and drop a loaded round into the chamber, if it goes in freely and stops with the base of the case even with the barrel hood (or whatever passes for a barrel hood on whatever gun you are checking) then that is the correct OAL for that load/bullet in that particular gun.

Someone can correct me if I'm wrong but most auto cartridges headspace on the mouth of the case and would stop at the same point in the barrel until the COL is long enough for the bullet to start engaging the rifling. This means that dangerously short COLs would still drop to the same depth in the chamber as safe ones.

That is true. My solution is to load as long as will fit in the magazine and barrel.

[Sarge]

The easiest way to get the proper OAL for any load/bullet is to take the barrel (out of gun) and drop a loaded round into the chamber, if it goes in freely and stops with the base of the case even with the barrel hood (or whatever passes for a barrel hood on whatever gun you are checking) then that is the correct OAL for that load/bullet in that particular gun.

Not really. Typically you want to load up a dummy kind of long and drop it in the barrel and keep running it through the press until it no longer touches the rifling. Then make sure that fits in you mag fine. Then work from there developing a load that is accurate, feeds well and is consistent.

Some loaders have formulas for measuring the chamber then dropping by a set amount. My painful, personal experience taught me to not cut it so close since bullets and oals can vary from round to round.

Using your technique you could drop a really short round in the chamber that groups like crap or won't feed right.

In my Production G34 I found 1.13 with mg 124 CMJ's to be more accurate than any other oal.

[Steve RA]

If you dropped a "really short round into the chamber" I seriously doubt if the base of the cartridge would be even with the end of the barrel hood.

[bdpaz]

If you dropped a "really short round into the chamber" I seriously doubt if the base of the cartridge would be even with the end of the barrel hood.

Why? It stops on the front of the case so, unless it is so long that the bullet hits the rifling, bullet seating depth doesn't come into play.

Edited to add: I don't have a barrel with me but I just sized a .45 case and the empty case drops right in the case gage and stops flush with the top - just like a loaded round.

For even more wacky fun, I put a 185 JHP in it upside down and seated it flush with the case mouth to make the shortest possible OAL. Normal crimp and it also case gages just fine. And no, the next step will NOT be to do the same thing plus primer & powder!

Edited July 28, 2011 by bdpaz

[Sarge]

If you dropped a "really short round into the chamber" I seriously doubt if the base of the cartridge would be even with the end of the barrel hood.

Huh? The case rests on its mouth in the chamber. That is what makes the preferable "kerplop" sound when you drop check ammo. Anything else and the round is either too long or not sized right.

[Steve RA]

I think if you measure a # of .45ACP cases, you will find that a goodly # of them will not be as long as the SAAMI specs for that cartridge. Also, a case gauge isn't the same as checking a # of actual gun barrels as, if you will, you'll find that the chamber depth will also vary considerably in them.

[bdpaz]

I think if you measure a # of .45ACP cases, you will find that a goodly # of them will not be as long as the SAAMI specs for that cartridge. Also, a case gauge isn't the same as checking a # of actual gun barrels as, if you will, you'll find that the chamber depth will also vary considerably in them.

That doesn't change the fact that unless it hits the rifling the bullet doesn't affect the how the cartridge drops into the barrel and your method will not prevent a dangerously short OAL. You can seat the bullet tip flush with the case mouth and it still will not drop below the barrel hood. Your method only catches OAls too long for the chamber.

Edited to add: I just stripped my .45 and dropped my dummy pseudo-wadcutter with the upside down JHP seated flush with the case mouth and it stopped at the hood with the normal kerplunk sound. So dangerously short rounds will chamber correctly with no signs that they are too short.

Edited July 28, 2011 by bdpaz

[bdpaz]

Just to clarify my previous post, short OAL isn't inherently dangerous. If it is intentional and that length is where your worked up a load it isn't a problem. But just assuming that any round that chambers is at a good OAL could be dangerous because a round that was shorter than intended will chamber correctly.