Tell me about OAL

jdthaddeus · January 20, 2000, 09:06 PM

Hello,

Need some advice about cartridge OAL (Over All Length).
I was making a load for my 9mm Glock using a Berry's flatpoint 124gr FMJ.
At first, I was trying to figure out how long to make it (how deep to seat the bullet). Finally, I just took a 124gr hollowpoint and used it as a model and made my load the same length. It worked just fine at the range.
Then, someone told me that I should make the catridge as long as possible, so that the bullet seats up to the rifling in the chamber. Okay, so I started lengthening the cartridge by seating the bullet shallower. I got my cartridge about as long as I feel comfortable and the ammo still cycles by hand and appears to chamber well by hand.
I have not fired any of this ammo yet, but I am told that OAL does not really matter except for accuracy. In other words, I can play around with OAL and not fear about blowing up my gun or whatever. Is this true?
As you can see, I just don't undertand OAL very much. Do I just play with it until it works? If the ammo cycles by hand does that mean it will chamber okay at the range?
I just don't want to make my cartridges too long and not be able to cycle them or damage the gun in some way (?). I cannot get to the range right now to try it out, and I want to ask advice first to make sure that I am not endangering the gun or anything by playing with the OAL and making my cartridge longer.

THANKS!

swifter... · January 20, 2000, 09:34 PM

Generally, with handgun cartridges, you run into disaster by seating the bullet too deep in the case, raising pressures. This is not a good idea with any autopistol...

I don't know if handfeeding will work the same as shooting, but IMHO, you were right to start with, match the OAL to what works.
Seating the bullet "closer to the rifling" for accuracy only matters if you can hold good enough that you are measuring differences in groups in the 0.001"!

Most good manuals will give some data on OAL, but mostly, go with what's reliable!

------------------
The Bill of Rights, and the Golden Rule are enough for civilized behavior. The rest is window dressing. Shoot carefully, swifter...

**Bud Helms** · January 20, 2000, 10:37 PM

jd,

I think Swifter's right. Moving the bullet out to "kiss" the rifling is probably worth the trouble with a bottle neck rifle cartridge in a rifle you're trying to accurize.

But in an auto pistol? Naaah. The thing about OAL is that it's only for a given bullet shape. For different bullet shapes, say a .45 230 gr Ball vs a .45 200 gr SWC, the OAL is different.

I'd seat the bullet out as far as you want, but make sure of three things <UL TYPE=SQUARE><LI>The cartridges feed up through the magazine easily <LI>The cartridges chamber reliably and <LI>The bullet doesn't jam the rifling when chambered</UL>

If you have a case gauge try two completely different shaped bullets in the same cartridge and move the bullets out as far as you can and still pass the gauge test. You'll be amazed at the different OAL for the different bullet shapes.

That's why I personally believe that too much emphasis is put on published OALs. In fact a reloading manual will give an OAL (three places to the right of the decimal point!) for a cartridge, then proceed to show the loads for round nose and pointed bullets. Doesn't make sense.

Your chamber has a maximum OAL for each bullet shape you shoot. That's the only OAL you care about.

Regards (a little long-winded tonight)

Sensop

ollie · January 21, 2000, 05:07 PM

Don't be nonchalant about OAL, especially in 9mm. The small case capacity of this caliber can easily cause pressure to rise into the twilight zone if the bullet is seated too deep. The published data is confusing (as well as incomplete) on this subject, given the great variety of bullets. The case gauge advice is excellent. ollie

jdthaddeus · January 22, 2000, 03:19 AM

Thanks!

alan · January 24, 2000, 01:26 AM

Max OAL for 9mm Luger is 1.169, usually using a ROUND NOSE BULLET. If you are using some other kind of bullet, say the flatpoint you mentioned, compare that bullets length with that of the hollow point you mentioned. I refer to projectile length, by the way. If they are the same, or quite similar, you can likely use the factory round OAL, overall length of cartridge, as a guide. You should not have a oal of loaded round shorter than about 1.10". To short an OAL can being both feeding and pressure problems. You might also check what the magazine will accept. Chamber dimensions are one thing, magazine dimensions can be another, and we are talking about hundreths or thousands of an inch. Could be, that in a particular gun, the magazing might be the limiting factor, re oal.

Walt Welch · January 24, 2000, 10:09 PM

Thaddeus, my wayward future colleague. You persist in straying from the straight and narrow path. Heed my words (for the rest of you, Thad and I go back a long time, and he is in med school; I am a retired MD).

You picked one of the worst possible cartridges to experiment with. Very slight changes in the variables, such as purposely seating a bullet 0.030" deeper, can cause a 28K cup load to go to 60K cup. This is bad, Thad.

OAL doesn't really count. It is the depth to which the bullet is seated in the case that really counts, as this determines the internal capacity. OAL is an indirect measure of bullet seatin depth. Which is specific to a particular bullet. So, don't apply OAL's for one 125 gr. bullet to another 125 gr. bullet. It may or may not be the same seating depth. Also, be particularly careful of your components. A while ago I was loading up some Rem 115gr. JHP's, when I noticed that the hollow point mouth looked smoother and less jagged on the new bullets I was using. This was due to a new manufacturing technique. Which left the new bullet 0.035" longer!! Had I loaded these to my usual OAL (as the ogive was the same), I would have been in serious trouble.
You may be in the same boat if you use old data which used the old style Rem bullet.

Which brings me to my main point. Here is how to get the best data.Go to this URL: http://www.shooters.com/

There, pick out either product search (which is quicker, but misses some things like Winchester) or directory (which is slow to load, but has everything in it). Get the powder manufacturer's or bullet manufacturer's data. It is the latest, most up to date data. Make sure that case brand, primer brand and type, bullet brand and type, and OAL are all given. Then load carefully. Cycle your rounds through your gun several times and check to make sure that the OAL doesn't change. I even had some factory ammo once that would noticeably seat the bullet deeper with ONE trip through the action. Be careful, OK? Walt

**Bud Helms** · January 25, 2000, 08:37 AM

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Walt Welch:
... OAL doesn't really count. It is the depth to which the bullet is seated in the case that really counts, as this determines the internal capacity. OAL is an indirect measure of bullet seatin depth. Which is specific to a particular bullet. So, don't apply OAL's for one 125 gr. bullet to another 125 gr. bullet. It may or may not be the same seating depth. ... Walt[/quote]

Wisdom!

Walt Welch · January 25, 2000, 02:08 PM

Sensop; more like good judgement, which is the result of experience. Experience, well, that is often the result of bad judgement.

Walt

**Bud Helms** · January 25, 2000, 08:36 PM

I know.

Like, "Here hold my beer and watch this!"

I got a tee shirt for that one.

January 20, 2000, 09:06 PM	#1
jdthaddeus Senior Member Join Date: November 20, 1999 Location: Az Posts: 470	Hello, Need some advice about cartridge OAL (Over All Length). I was making a load for my 9mm Glock using a Berry's flatpoint 124gr FMJ. At first, I was trying to figure out how long to make it (how deep to seat the bullet). Finally, I just took a 124gr hollowpoint and used it as a model and made my load the same length. It worked just fine at the range. Then, someone told me that I should make the catridge as long as possible, so that the bullet seats up to the rifling in the chamber. Okay, so I started lengthening the cartridge by seating the bullet shallower. I got my cartridge about as long as I feel comfortable and the ammo still cycles by hand and appears to chamber well by hand. I have not fired any of this ammo yet, but I am told that OAL does not really matter except for accuracy. In other words, I can play around with OAL and not fear about blowing up my gun or whatever. Is this true? As you can see, I just don't undertand OAL very much. Do I just play with it until it works? If the ammo cycles by hand does that mean it will chamber okay at the range? I just don't want to make my cartridges too long and not be able to cycle them or damage the gun in some way (?). I cannot get to the range right now to try it out, and I want to ask advice first to make sure that I am not endangering the gun or anything by playing with the OAL and making my cartridge longer. THANKS!

January 20, 2000, 09:34 PM	#2
swifter... Senior Member Join Date: March 16, 1999 Location: So. CA Mountains Posts: 540	Generally, with handgun cartridges, you run into disaster by seating the bullet too deep in the case, raising pressures. This is not a good idea with any autopistol... I don't know if handfeeding will work the same as shooting, but IMHO, you were right to start with, match the OAL to what works. Seating the bullet "closer to the rifling" for accuracy only matters if you can hold good enough that you are measuring differences in groups in the 0.001"! Most good manuals will give some data on OAL, but mostly, go with what's reliable! ------------------ The Bill of Rights, and the Golden Rule are enough for civilized behavior. The rest is window dressing. Shoot carefully, swifter...

January 20, 2000, 10:37 PM	#3
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	jd, I think Swifter's right. Moving the bullet out to "kiss" the rifling is probably worth the trouble with a bottle neck rifle cartridge in a rifle you're trying to accurize. But in an auto pistol? Naaah. The thing about OAL is that it's only for a given bullet shape. For different bullet shapes, say a .45 230 gr Ball vs a .45 200 gr SWC, the OAL is different. I'd seat the bullet out as far as you want, but make sure of three things <UL TYPE=SQUARE><LI>The cartridges feed up through the magazine easily <LI>The cartridges chamber reliably and <LI>The bullet doesn't jam the rifling when chambered</UL> If you have a case gauge try two completely different shaped bullets in the same cartridge and move the bullets out as far as you can and still pass the gauge test. You'll be amazed at the different OAL for the different bullet shapes. That's why I personally believe that too much emphasis is put on published OALs. In fact a reloading manual will give an OAL (three places to the right of the decimal point!) for a cartridge, then proceed to show the loads for round nose and pointed bullets. Doesn't make sense. Your chamber has a maximum OAL for each bullet shape you shoot. That's the only OAL you care about. Regards (a little long-winded tonight) Sensop

January 21, 2000, 05:07 PM	#4
ollie Junior Member Join Date: January 9, 2000 Location: toledo,oh usa Posts: 4	Don't be nonchalant about OAL, especially in 9mm. The small case capacity of this caliber can easily cause pressure to rise into the twilight zone if the bullet is seated too deep. The published data is confusing (as well as incomplete) on this subject, given the great variety of bullets. The case gauge advice is excellent. ollie

January 22, 2000, 03:19 AM	#5
jdthaddeus Senior Member Join Date: November 20, 1999 Location: Az Posts: 470	Thanks!

January 24, 2000, 01:26 AM	#6
alan Senior Member Join Date: June 7, 1999 Posts: 3,847	Max OAL for 9mm Luger is 1.169, usually using a ROUND NOSE BULLET. If you are using some other kind of bullet, say the flatpoint you mentioned, compare that bullets length with that of the hollow point you mentioned. I refer to projectile length, by the way. If they are the same, or quite similar, you can likely use the factory round OAL, overall length of cartridge, as a guide. You should not have a oal of loaded round shorter than about 1.10". To short an OAL can being both feeding and pressure problems. You might also check what the magazine will accept. Chamber dimensions are one thing, magazine dimensions can be another, and we are talking about hundreths or thousands of an inch. Could be, that in a particular gun, the magazing might be the limiting factor, re oal.

January 24, 2000, 10:09 PM	#7
Walt Welch Senior Member Join Date: November 3, 1998 Location: Alamo, CA Posts: 424	Thaddeus, my wayward future colleague. You persist in straying from the straight and narrow path. Heed my words (for the rest of you, Thad and I go back a long time, and he is in med school; I am a retired MD). You picked one of the worst possible cartridges to experiment with. Very slight changes in the variables, such as purposely seating a bullet 0.030" deeper, can cause a 28K cup load to go to 60K cup. This is bad, Thad. OAL doesn't really count. It is the depth to which the bullet is seated in the case that really counts, as this determines the internal capacity. OAL is an indirect measure of bullet seatin depth. Which is specific to a particular bullet. So, don't apply OAL's for one 125 gr. bullet to another 125 gr. bullet. It may or may not be the same seating depth. Also, be particularly careful of your components. A while ago I was loading up some Rem 115gr. JHP's, when I noticed that the hollow point mouth looked smoother and less jagged on the new bullets I was using. This was due to a new manufacturing technique. Which left the new bullet 0.035" longer!! Had I loaded these to my usual OAL (as the ogive was the same), I would have been in serious trouble. You may be in the same boat if you use old data which used the old style Rem bullet. Which brings me to my main point. Here is how to get the best data.Go to this URL: http://www.shooters.com/ There, pick out either product search (which is quicker, but misses some things like Winchester) or directory (which is slow to load, but has everything in it). Get the powder manufacturer's or bullet manufacturer's data. It is the latest, most up to date data. Make sure that case brand, primer brand and type, bullet brand and type, and OAL are all given. Then load carefully. Cycle your rounds through your gun several times and check to make sure that the OAL doesn't change. I even had some factory ammo once that would noticeably seat the bullet deeper with ONE trip through the action. Be careful, OK? Walt

January 25, 2000, 08:37 AM	#8
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Walt Welch: ... OAL doesn't really count. It is the depth to which the bullet is seated in the case that really counts, as this determines the internal capacity. OAL is an indirect measure of bullet seatin depth. Which is specific to a particular bullet. So, don't apply OAL's for one 125 gr. bullet to another 125 gr. bullet. It may or may not be the same seating depth. ... Walt[/quote] Wisdom!

January 25, 2000, 02:08 PM	#9
Walt Welch Senior Member Join Date: November 3, 1998 Location: Alamo, CA Posts: 424	Sensop; more like good judgement, which is the result of experience. Experience, well, that is often the result of bad judgement. Walt

January 25, 2000, 08:36 PM	#10
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	I know. Like, "Here hold my beer and watch this!" I got a tee shirt for that one.