OAL 9mm

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lovig214

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I was reading a thread about over all length and it said to drop the bullet you are going to use and then slide a case over the bullet that has been shot but not re sized then remove it and measure it and then reduce the length by about .020. I did this but what has me puzzled is that the oal that it will except is much longer then the max oal that any data gives. Can you guys shed some light on this. Thanks Craig
 
Sounds silly as heck to me. Use the O.A.L. in the load book, unless all they show is the SAMMI max, then use an O.A.L. that feeds well. Adjust the charge if needed.

What bullet and someone here has probably used it and can give suggestions.
 
That didn't read quite right. The brass had been shot not the bullet. I am going to show my Ignorance but how do I know if i need to adjust the charge?
 
I understood the brass was shot and the bullet wasn't.

If a load book shows a 9MM bullet loaded to 1.135 and you load it at 1.125 because it feeds better in your gun, you have less usable case capacity now due to the deeper seating depth. In .45 ACP with a bigger case and much lower operating pressure a .010 deeper seating depth would be no big deal, but in the 9MM with its little case and much higher operating pressure it needs to be taken into consideration.
 
thanks walkalong I get it now. Is there a calculation to determine how much to decrease the charge? Thanks Craig
 
Unless I'm reading incorrectly, OP stated that his chamber accepts an OAL longer than anything published. In this case, you can use load data for the shorter OAL without modification. But you should make sure the bullets can fit in the magazine and can feed and eject, properly. It's commonly accepted wisdom that ammo tends be more accurate when the cartridge is closer to the max OAL that chambers in that gun.
 
Load the bullet so it fits the magazine, chambers easily, and sits solidly in the case. I load mine so that most of the bullet shank is in the case and some of the shank is outside the case mouth. For example, I seat TC profiles to about 1.100" or less. I seat RN between 1.100" and 1.150" depending on weight. 115's have less shank so I seat them short. 115gr hollow based bullets have more shank so I seat them long. I seat 124's and 147's long.
 
Mr 214 -
The mentioned exercise is necessary on many eastern European guns like the CZ and XD, especially when shooting bullets like the XTP that bring the full .355 diameter out in front of the case mouth. The point is, some 9mm barrels don't like some 9mm bullets, but you'll never know until you do the exercise.

Let's say that the test proves a certain bullet can be loaded at 1.150" in your barrel. Then...
A) You are free to use any load data for the same construction and weight bullet which shows an OAL shorter or equal to 1.150", and
B) You can safely use any OAL between 1.150 and the OAL shown for the chosen load.

So you can always go longer on the OAL as long as your bullet is known to be free of the rifling. But you can't guess at the maximum OAL, you should do the experiment and know. Sometimes going slightly longer is desirable because of known feeding issues or to avoid a compressed load.


Conversely, if you have a wonderful load showing an OAL of 1.125", but the "bullet test" shows your maximum safe OAL to be 1.100", then you need to find another load, use software like QuickLoad, or proportionalize the load down.

And always remember, with any new load you should begin at the "starting load" and work your way back up.
 
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I was reading a thread about over all length and it said to drop the bullet you are going to use and then slide a case over the bullet that has been shot but not re sized then remove it and measure it and then reduce the length by about .020.
Click to expand...

I've tried this trick before and could never get it to work. Whats probably happening is that you're bullet is getting pulled out a little bit as you pull the casing back out of the barrel, hence the longer than max OAL.

I just keep loading dummy rounds (no powder no primer) shorter and shorter until I get a round that spins freely in the chamber (removed from the gun) and also drops free. Not sure how correct that is maybe a few others can chime in but has worked for me.
 
Aghh. I just figured out (I think) which key words were missing from the OP's post. Got it now. Yep, but we don't know how far the bullet gets jammed into the lands doing it that way.

Just do like 919v posted, and if you have a short leade try this to find your max and go from there.
 
It's commonly accepted wisdom that ammo tends be more accurate when the cartridge is closer to the max OAL that chambers in that gun.
Click to expand...

I was told in another thread on AOL that this is true because the bullet engages the rifling sooner. Maybe even immediatly. Makes sense to me.
 
I was told in another thread on AOL that this is true because the bullet engages the rifling sooner.
It's commonly accepted wisdom that ammo tends be more accurate when the cartridge is closer to the max OAL that chambers in that gun.
Click to expand...
Click to expand...
Yes, the sooner the nose of the bullet engages the rifling, the less hot gas escapes around the bullet resulting in more consistent the chamber pressure build up. For this reason, some reloaders will load lead bullets as long as they possibly can feed/chamber reliably, which also provides better obturation and less leading.
 
rfwobbly said:
Conversely, if you have a wonderful load showing an OAL of 1.125", but the "bullet test" shows your maximum safe OAL to be 1.100", then you need to find another load, use software like QuickLoad, or proportionalize the load down.
Click to expand...

If one has a "Wonderful" load that shows no sign of pressure then why make any change at all. Often trying to improve on "wonderful" just makes it worse.
 
I am new to loading, I tried the drop in test. I could not get things to make sense. So I took the calipers to a few rounds of Federal American Eagle with the same type of bullet and ran with it. I am loading FMJ RN bullets at 1.150 for my G17.
 
as rfwobbly said: The test works well for what it's intended. Remember 9mm 'seats on the case mouth". With the wrong bullet and oal the bullet will hit the lands before it hits the case mouth.
Example-- A Glock 9mm might really like a Zero 125gr JHP bullet with an oal of 1.15"

My CZ won't seat on the case mouth if "this" bullet is loaded longer than 1.1". The bullet will hit the lands 'before' it's seated properly. Good way to have big problems.

The test is for the "MAXIMUM" length "YOUR BBL" will accept with "THIS SPECIFIC BULLET". Every gun and every different type (includes different manufacturers)of bullet will give different results.

Shorter than the maximum possible oal is fine, if it's good with the load data book.

Lastly, the subtract .02" purpose is to give your loader and your gun a little margin for error. I subtract less than that .

The 125gr Zero I mentioned abovehits the CZ's lands at about 1.109"; so I load to 1.1".
 
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Thanks 1sow. Like I mentioned this is super information I am learning and it is all starting to make some sense. Cool Craig
 
You're very welcome. rfwobbly probably gave me the info originally.

A spent case with your 'new' bullet just slightly seated by hand, press it in slowly 'til it "seats on the case mouth" firmly. Then gently pull it back out and measure the oal. Do this at least 3X for consistent reults. If your loader gives you +/- .003" consistency, add a little leg room and go .01" LESS on your MAX oal finding.
 
TH3180 said:
I am new to loading, I tried the drop in test. I could not get things to make sense. So I took the calipers to a few rounds of Federal American Eagle with the same type of bullet and ran with it. I am loading FMJ RN bullets at 1.150 for my G17.
Click to expand...
To expand a little bit on my other post. I just did the barrel test on 10 cases and 10 bullets. I came up with an average of 1.245, which is .076 over max OAL of 1.169. I am using the Speer manual. It has an OAL of 1.135 for there testing. At 1.150 OAL I am well within there test load and max OAL. I have no cycling problems so far, so I am going to stick with 1.150. I may mess with it when I get more experianced at loading, but for now why fix something that's not broke.
 
Your right. The test showed 'your' bullet' at your oal' will chamber properly in 'your gun'.

If the test showed 1.14", then you couldn't have used the 1.15" oal.

Success is good.
 
Originally Posted by rfwobbly
Conversely, if you have a wonderful load showing an OAL of 1.125", but the "bullet test" shows your maximum safe OAL to be 1.100", then you need to find another load, use software like QuickLoad, or proportionalize the load down.
Click to expand...

If one has a "Wonderful" load that shows no sign of pressure then why make any change at all. Often trying to improve on "wonderful" just makes it worse.
Click to expand...

My statement was not clear. I apologize. What I meant by "wonderful" was a load that was highly thought of and recommended by several respected shooters, not one you had worked up with the gun in question.
 
Color your bullet with a black permanent marker. Let the bullet dry for a moment. Set the bullet in a fired case that has not been sized and push it in just so that the case holds it in place. Insert the bullet into the chamber and let your slide close on it. Remove the case and the bullet(sometimes you have to push the bullet off the rifling with a cleaning rod). Inspect your case for a pretty clear line of where the brass scraped the permanent marker to on your bullet. Set your seating die so that it will seat the bullet approximately .010-.020" deeper than the line on the bullet. Ensure that the load will fit into your magazine. If not, load to the maximum length that your magazine will allow. This load is great for accuracy, sometimes maybe not the highest velocity, but quicker powders do the trick there. The trick to this is that you are now loading based upon the ogive of the bullet and your seating die is set to load all of the different bullet types you may use to a consistent distance from the rifling of your barrel. My hollow points connect with my rifling at the same time as my fmj's even though the fmj's have a considerably longer OAL.
 
Example-- A Glock 9mm might really like a Zero 125gr JHP bullet with an oal of 1.15"

My CZ won't seat on the case mouth if "this" bullet is loaded longer than 1.1".
Click to expand...

My Glock takes Zero JHP out past 1.3", IIRC. My DP-51 is even tighter than a CZ, apparently. I need to take it all the way down to 1.085". One of these days I might ream the chamber on it.
 
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