OAL Question

[ronaldlhedrick]

Please bear with me as I am a newbie.

I have a Lyman 49th reloading manual. When I look at the Caliber and the particular bullet I want to load, there is an OAL (Overall Length). Is that OAL the Minimum or the Maximum for that bullet or load?

For instance the 40 S&W on page 362 of the Lyman 49th says in the diagram the Length is 1.135" and the 175gr. Lead bullet #401638 on page 364 has an OAL of 1.100".

Should I be between those two measurements?

 

[16in50calNavalRifle]

Welcome to the forum, and don't hestitate to ask questions. Great group of very knowledgeable reloaders here (this does not include myself, I'm still in the apprentice category).

For semi-auto pistol ammo, your OAL is (usually) determined by the gun itself - the chamber mostly, and sometimes the feeding ramp and the magazine and the way they interact. For most revolver loads, if there is a canneleure on the bullet, that it where you crimp, so that determines your OAL.

So the "paper" OAL in reloading data mostly is to give you complete info about the load - that is, give you the OAL that was used to achieve the velocity reported, using the charge listed. It goes along with the test barrel length and other info to give you a complete picture, it's not so much a hard limit for your guidance.

There are several excellent threads here explaining/illustrating how to determine maximum OAL and best OAL for your 40 cal. Search threads by member "bds" and moderator Walkalong, among others.

One of them or another will probably be along to link some of those threads if you don't find them first.

My welcome advice to this forum is to use the search function, patiently and diligently. You will usually find your answer without too much trouble - PLUS learn lots of other things along the way (take the time to follow those little related tangents from your topic). That is how I approach a reloading question, and it has and continues to be a tremendous help.

 

[ronaldlhedrick]

I have done quite a bit of reading on it. And it seems to me like in it's most basic terms; I want to seat the bullet the smallest amount possible and still have the firearm function properly without exceeding the diagram in the reloading manual.

I know there is a lot that goes in to figuring that out. But as long as I understand that statement to be true. Then I believe I have my answer to my question.

 

[16in50calNavalRifle]

If you seat to max OAL for your pistol, using a charge within the range provided in the manual data, then it seems to me you'll have a safe, function round. A difference of 0.035 inch - if the round still chambers and ejects normally from your gun - should not be of any importance.

Unless you're talking accuracy. But I think that's usually a function of charge/pressure/velocity, all of which can vary while using the same OAL that works in your gun. (I don't fuss much over the accuracy issue as the error factor introduced by the operator - me - vastly exceeds any error factor I can tweak by adding or dropping .2 grain of HP-38 ......)

 

[Potatohead]

I want to seat the bullet the smallest amount possible and still have the firearm function properly without exceeding the diagram in the reloading manual.

A lot of folks do seat as short as possible without going below the recommended oal, yes. I struggled with OAL at first myself. I dont want to minimize any dangers, but most likely your gun wont just automatically explode or anything if you move your OAL around some and you ended up a little under the recommended OAL (PROVIDED YOUR CHARGE IS NOT DOUBLED OR SOMETHING, AND THAT YOU ARE STARTING AT THE START CHARGE)...You will find that their is a safe range of OALs usually. Like in 9mm, Im usually between 1.10" and 1.15". (I have to establish what the range is with the plunk test with each different bullet I use).

and ALWAYS start low and work up

I believe in most data, it's more of a "recommended" OAL instead of a minimum. Somebody correct me there if Im wrong, as I do think I recall some of them listed as "min".

 

[ronaldlhedrick]

Thanks for your help. That helped me clear that up in my head.

 

[Potatohead]

Hopefully I didnt confuse more with my scatterbrained delivery..

 

[ronaldlhedrick]

Nope. That was great. Thank you

 

[gamestalker]

The SAAMI maximum us 1,135", minimum oal is 1.085" I believe, as I'm going on memory, but that can be verified in your reloading books.

As far as finding the oal for a particular bullet, that can be easily accomplished by doing the plunk test. Personally, I use the longest oal that will function reliably, and will fit the magazine.

However, many bullet manufacturer's will include the tested oal, which in most instances will function fine in most firearms.

With AL-ing cartridges, pressures will increase the shorter the oal. With high pressure cartridges, such as .40 cal. and 9mm, even small variations of .010" in OAL can have a very significant effect on pressures. This is why bullet set is such a serious matter, and can have catastrophic results.

Bottle neck loads are some what different, in which case pressures will increase when the bullets is seated closer to the lands, and decrease as you get further away from the lands.

GS

 

[Sunray]

Best to seat to the max OAL. Manuals will give lengths for various bullet weights, but the Max will always work. Most important that a loaded pistol cartridge fits in the mag.

 

[Walkalong]

1.135 is the max OAL for .40 S&W. Some guns won't accept that with some bullets though. Plus the OAL needs to function 100% in your pistol. A lot of people like to start long and work back shorter if that doesn't work.

the particular bullet I want to load

Which bullet would that be, that would help us guess what OAL to use, or at least to start at.


http://www.thehighroad.org/showthread.php?t=506678

 

[ronaldlhedrick]

1.135 is the max OAL for .40 S&W. Some guns won't accept that with some bullets though. Plus the OAL needs to function 100% in your pistol. A lot of people like to start long and work back shorter if that doesn't work.

Which bullet would that be, that would help us guess what OAL to use, or at least to start at.


http://www.thehighroad.org/showthread.php?t=506678

We are loading 40 S&W 175 gr. Lee Lead Cast bullet. We set the OAL to 1.125. This seems to cycle very well through the Magazine and the Chamber. ( of course that was tested with bullet seated in a case without powder and primer for safety.)

 

[Walkalong]

This TrFP?

http://www.midwayusa.com/product/56...s-and-w-401-diameter-175-grain-truncated-cone

We set the OAL to 1.125.

Ok, so you are not looking for an OAL, you just want to know if you are in the ballpark concerned pressure with the data?

Should I be between those two measurements?

Since, as posted, 1.135 is the Max OAL length for .40, you probably want to stay under that. Are you saying that the Lyman #49 lists 1.100 for the bullet you are using, or another bullet?

1.125 certainly sounds reasonable to me for the bullet I linked to.

 

[LiveLife]

When I tested MBC lead 140 TCFP/155 SWC/170 SWC/180 TCFP bullets, I started out with SAAMI max of 1.135" and decreased the lengths until they freely dropped in the chamber and turned without hitting the rifling. Then I decreased the lengths further until they reliably fed/chambered from the magazine.

Picture below shows the OALs that worked with Glock 22/23/27 using factory and Lone Wolf barrels which range from 1.120" to 1.125". OAL that works for Lee 175 gr bullet and your pistol/barrel may be different but if they pass the barrel and feed/chamber reliably from the magazine, you are good to go.

 

[16in50calNavalRifle]

Seems like we're into detailed answers at this point, but wanted to amend my earlier comment. As Gamestalker notes, in high-pressure cartridges like 40 the OAL can be important due to pressure considerations. What I *meant* to say was that, keeping charge levels and thus pressures in mind, there was no particular importance to OAL in itself, and one can safely load various quantities of powder and use various OALs with a given bullet.

Like the others, I use the plunk test (see my earlier referenced but not linked threads in this forum on that topic) and max OAL for my pistol/magazine. Margin of safety, and efficiency. My reloading is for fun, practice, plinking, informal competitions, so while my quality control is extremely high, my "standards" - beyond safe, functioning performance -are loose.


P.S. - and ..... as expected, bds comes along with one of his excellent, incredibly well illustrated posts ..... I told you, ronaldhedrick, this place is the best!

 

[LiveLife]

Thanks for the kind words.

Also, if you are concerned about pressure, I would definitely check neck tension/bullet setback which can significantly increase chamber pressure. My QC check for bullet setback is measuring OAL/COL before and after feeding the round from the magazine and letting the slide go without riding it.

With 401" sized lead bullets, I do not get bullet setback using different headstamp cases. If you measure bullet setback more than a few thousandths, you have neck tension issue and that needs to be addressed.

Best to seat to the max OAL. Manuals will give lengths for various bullet weights, but the Max will always work.

That's what I used to think but found that sometimes max OAL/COL may not reliably feed/chamber from the magazine and I needed to decrease the OAL shorter than max OAL to use as "working OAL".

And with 40S&W, depending on the barrel/bullet, I needed to use longer than SAAMI max to squeeze more accuracy out of my loads. In the Herco for 40S&W thread, I tested 1.135"/1.137"/1.139"/1.141"/1.143" OALs with lead 180 gr TCFP to reduce high pressure gas leakage and improve accuracy. (1.149" was the length that would fit the magazine and 1.145" would reliably feed/chamber from the magazine but since resized range brass case lengths varied for headspacing, I used 1.143" to compensate) - http://www.thehighroad.org/showthread.php?p=9362819#post9362819

With RMR's 180 gr RNFP bullet, I used 1.155" OAL with very good results - http://www.thehighroad.org/showthread.php?p=9644303#post9644303

 

[Potatohead]

Best to seat to the max OAL.

I think I see where you're going here but taken alone, that could be a bit misleading. Its possible one could get better accuracy at a shorter-than-max OAL..?

 

[picker]

As an amateur Reloader when I see trusted published data that states Min and Max "coal" I think accuracy for my gun is somewhere in between those two values, I start long and low and work up and shorter.
Best/joe

 

[LiveLife]

when I see trusted published data that states Min and Max "coal" I think accuracy for my gun is somewhere in between those two values

"Working" and "most accurate" OAL/COL used depend on the bullet nose/base shape/length and pistol/barrel used. Most published load data were tested using universal barrel fixtures, essentially single shot fixtures without slides or magazines.

So using published OAL won't ensure finished rounds will reliably feed/chamber from the magazine in your pistols or produce the most accurate load and us reloaders must determine what length will work with our pistols/barrels.

An example of using listed OAL not working is several published load data will list 1.120" to 1.150" for 9mm 124 gr RN bullet but for newer non-stepped lead/coated RN bullets with longer bullet base/bearing surface, shorter 1.080" to 1.100" need to be used to not hit the start of rifling and reliably feed/chamber from the magazine.


As to accuracy, it's been my experience that more consistent shot groups result from more consistent muzzle velocities/lower standard deviation numbers which result from more consistent chamber pressures. Many factory barrels and even match barrels have longer leade/freebore which leak more high pressure gas at the start of powder ignition (until bullet's bearing surface engages the rifling to build chamber pressures) so some reloaders/match shooters tend to use the longest OAL/COL that will work with their pistols, even longer than SAAMI max length, to reduce gas leakage and produce more accurate loads.

In post #16, I illustrated two examples of using longer than published OAL for more accurate loads. For 40S&W, SAAMI max length is 1.135" and many published load data will list 1.125" for 180 gr TCFP bullets. If you browse brianenos forum, many match shooters will use longer 1.143" - 1.145" OAL. For my test pistols/barrels, I tested up to 1.143" for lead TCFP bullet and 1.155" for RMR plated RNFP bullet which produced greater accuracy than 1.125"/1.135" OAL loads.

 

[Potatohead]

Sure wish we had somebody that would test all this stuff so it wouldnt just be conjecture.




Just kidding BDS

 

[picker]

Interesting...............Thanks/joe

 

[picker]

So, what I need to do is get my 40 barrel do a plunk test to determine the guns COAL, load a few mild loads to make sure it functions reliably, then work my powder load up to the sweet spot, looking for 50+ yd accuracy from a stock Glock 23 and I realize a stock 23 is not a target gun, but it's what I like to do.
Best/joe

 

[LiveLife]

Yes. But keep in mind that Glock barrels have longer leade with smoother start of rifling that will often accommodate longer than SAAMI max length. So with 180/165 gr TCFP/RNFP bullets, you'll be limited by the magazine which is 1.149" (RMR 180 gr RNFP worked at 1.155").

With typical TCFP bullets, your max OAL can be 1.149" which will drop in the chamber and spin without hitting the rifling. But when I loaded my magazine with more than one dummy round (no powder/no primer), they jammed against the magazine body and 1.145" worked better.

So 1.145" could be your max OAL (depending on the bullet) for the barrel but you will need to determine if this is the working OAL by function testing. To check, I load the max OAL dummy round from the magazine and release the slide without riding it. For G22/G23/G27, 1.143" fed and chambered reliably and I used 1.143" as my "working OAL".

Using the working OAL, you can conduct your powder work up to first determine the charge that will reliably cycle the slide and extract/eject the spent cases then look for charge that will produce the smallest shot groups.

looking for 50+ yd accuracy from a stock Glock 23 and I realize a stock 23 is not a target gun, but it's what I like to do.

I usually determine the accuracy of loads at 10-15 yards. Once the most accurate load is identified, I test the load at 25 yards. With accurate loads and stock Glocks, sub 2" shot groups at 25 yards is possible but 3"-4" is more typical with my G23.

 

[picker]

Thanks bds for that good information, I usually stick to Hornady's "HAP" bullets and I have tried Rainer/Berrys and a few others Jacketed and plated, just seems like the HAP shoots the best for me.So Im betting 1.43 will be very close.
Best/joe
PS, I can see I need to start shopping for a chrono[smile]

 

[LiveLife]

seems like the HAP shoots the best for me.

HAP was optimized for match shooting and seems to shoot well for everyone else too.

Since it does have different nose profile/ogive than the bullets I tested, 1.143" may not be the working OAL you end up with.

And yes, chrono is beneficial in seeing where your loads are.