OAL Differences

[blujax01]

My Lyman says 45 ACP 230 gr. TMJ Round Nose should have an overall length of 1.275.
Hodgdon Reloading Data Center says 1.200.

I am a nut when it comes to measurements. I use electronic calipers that are calibrated on an annual basis. I try very hard to hold the tolerances shown in the Lyman handbook and only came across the Hodgdon data when I started loading Titegroup. (Lyman doesn't show Titegroup with 230 TMJ).
What are the consequences of making a longer or shorter round? Will this significantly affect the pressure or velocity? Or should I just have another cup of coffee and relax?

 

[jepp2]

What impacts pressure is bullet seating depth. This is the portion of the bullet inside the brass case.

If you increase bullet seating depth (which decreases OAL), you increase pressure. How much you increase the pressure is not a linear function.

So when you compare OAL's, if different bullets are involved, the seating depth could be the same for different OAL's or they might be different.

This is just another reason why starting near the minimum load is the right thing to do. A couple of thousandth's will not make much difference.

The 0.075" is A LOT.

You also need to determine the length that functions best in your pistol (assuming you are not loading for a revolver) for that bullet profile.

Will it significantly affect the pressure? 0.075" will.

 

[blujax01]

Lyman shows all 230 round nose at 1.275. Hodgdon shows all round nose 230 at 1.200. Odd, eh?

 

[Rule3]

I called and question Hodgdons on their OAL some time ago.
As I also found it odd.

The 1.200 OAL is what they used to do a uniform test of the particular bullet with all the listed powders. Basically they said it is safe to use at the shorter OAL without having a pressure problem. So using their powders in their min/ max range you are safe (per them)

It does not mean that is the OAL you need to use. I do not load mine that short.

 

[Beemer-mark]

You need to determine what functions best in your pistol. OAL, like everything else in a reloading manual, is a guide. It is not an absolute. The 1.275 is the minimum chamber length. Generally accuracy improves if the bullet is close to the barrel lands. Pressure increases greatly if the bullet actually impacts the lands when chambered.

All of my 1911s will chamber a round that is 1.275 in OAL. However some of them will not eject a loaded round, the round gets hung up in the ejection port and is a PIA to get out. So I load mine around 1.22 with a cast 230 grain bullet.

 

[blujax01]

So if I use Hodgdon loading data (grain) and the longer Lyman OAL, it will no doubt be safe but the pressure and velocity data will not be correct, yes?
Sounds like I should hold Lyman tolerance and only shorten the round if I had feeding problems.
And ask for a chronograph for my Birthday!

 

[Rule3]

My Lyman says 45 ACP 230 gr. TMJ Round Nose should have an overall length of 1.275.
Hodgdon Reloading Data Center says 1.200.

I am a nut (OCD if you will) about measurements and like things black and white also.

But your above post is not entirely correct. If you look at the data again, none of it is for 230 gr TMJ RN.

It is for FN. Which will make a difference in OAL but not necessarily how much of the bullet is in the case.

The 230 RN info is lead.

I looked in my brand spanking new Christmas Hornady Handbook and their OAL for their 230gr RN is 1.230 it is discontinued as is the FMJ FP which they loaded at 1.200.

I settled on 1.250 for all my plated, FMJ and lead 230gr RN bullets. They work in all my 45's.

Beemer,
1.275 is a Max OAL not Min

 

[Dragon88]

You are worrying way too much about OAL.

 

[Rule3]

You are worrying way too much about OAL.

How can you say that?

One should not "worry" but be very concerned about OAL. Other than powder charge what other factor is most important in reloading???

 

[Roadranger]

I load all of my 200/230 plated or jacketed round nose bullets to 1.24 to 1.25" over 5 grains of Titegroup. They fit and feed just about from any magazine and are more accurate than I can shoot them. Cast bullets vary slightly depending on shape, some as short as 1.21", but never longer than 1.25". Bob!

 

[firearmsunlimited]

How can you say that?

One should not "worry" but be very concerned about OAL. Other than powder charge what other factor is most important in reloading???

As has been already pointed out in this thread COAL should be determined by function in your particular firearm. Pressures will rise significantly especially in handguns when the seating is well below suggested COAL. Loosely crimped bulletscan have devastating results when the bullet slides back into the case resulting from recoil. Misinterpretation of published reloading data can be very dangerous. Be sure you are applying data for the bullet and other components that you are using. Unquestionably seating depth for handguns in relationship to accuracy is not nearly as important as it is in rifles. The statement that accuracy increases the closer to the jamb point the bullet ogive is - is absolutely incorrect. We have seen target groups shrink considerably when bullets are seated relatively far off of the rifling. As you rightly point out, powder charge weight consistency will impact accuracy. One of the most overlooked but most important factors that impact handgun accuracy is case length consistency. A couple of other areas of concern are uniformity of primer pockets and flash holes. Good luck with finding a pet load for your firearm.

 

[Rule3]

Firearms,

Why are you quoting me?

 

[Dragon88]

How can you say that?

One should not "worry" but be very concerned about OAL. Other than powder charge what other factor is most important in reloading???

Just about everything else. Reducing OAL does reduce case capacity, however there is such a wide working range that to be meticulously measuring each round and worry about five thousandths is a waste of time IMO. Find a suitable COAL that functions well in your firearms and matches your load data and that's it. For loads using a roll crimp and cannelure on the bullet, I don't even pull out the calipers. OAL is set by those factors and you simply load accordingly.

I have been really concerned about OAL only once, when I was loading +P 44 magnum rounds. I made sure my bullet and seating depth matched my load data exactly or toward a safer margin and that was it, 2 minutes of my time.

 

[Gun 4 Fun]

Beemer,
1.275 is a Max OAL not Min

OCD-
He said minimum chamber length, which is basically the thing that sets maximum COAL if you consider the throat as part of the chamber, which many do when trying to determine COAL max.


Also, while seating depth is very important and should be paid close attention to, it is as has already been stated, not an absolute. You have to ask yourself- am I working with a max load, in the middle, or at the bottom? Obviously the closer to the bottom of listed loads you are working, the less you need to be concerned about seating depth changes putting you over the max pressure limit.

Something that almost always gets overlooked is bearing surface type, and length of that bearing surface. Is it longer? Does it have relief grooves of any kind including a cannelure? All those things will cause variations in pressure, sometimes as much as, or more than varying the seating depth a couple thousanths.

 

[Rule3]

Just about everything else. Reducing OAL does reduce case capacity, however there is such a wide working range that to be meticulously measuring each round and worry about five thousandths is a waste of time IMO. Find a suitable COAL that functions well in your firearms and matches your load data and that's it. For loads using a roll crimp and cannelure on the bullet, I don't even pull out the calipers. OAL is set by those factors and you simply load accordingly.

I have been really concerned about OAL only once, when I was loading +P 44 magnum rounds. I made sure my bullet and seating depth matched my load data exactly or toward a safer margin and that was it, 2 minutes of my time.

This is not what you said originally.No one said anything about meticulously measuring each case nor about a 5 thousands difference??
We are not talking about revolver loads and bullets with a cannelure. The OP was asking a specific question regarding the discrepancies in OAL. The main discrepancy was comparing FN bullets to RN which will have a different OAL. To simply state "you worry too much about OAL" is a great simplification.
In 45 Auto yes there are variations but be low pressure there is some wiggle room. Load some 40 SW and start changing the OAL and you have a different situation.
Powder charge and OAL go together, change one or the other and you have a completely different load then what's in "the book". Many different bullets of the same weight but different shape or profile require different seating depths which in turn create different case pressure. Stating that OAL is not to worry about is akin to saying what's a few more grs of powder gonna do?

Size does matter

 

[blujax01]

Is the overall length shown in the reloading tables maximum, minimum, or nominal? And if it is nominal, what tolerance applies? +/-???

In God we trust. All others bring data!

 

[OKFC05]

Is the overall length shown in the reloading tables maximum, minimum, or nominal? And if it is nominal, what tolerance applies? +/-???
In God we trust. All others bring data!

The tolerance is not absolute. It is more of an "you're safe from here to the edge of the cliff" type thing. If you are at way low pressure and loaded long, it's like being 100 feet from the cliff versus one foot. If you're already at max pressure and want to load shorter, you have no tolerance.

A chronograph is a wonderful thing.

 

[firearmsunlimited]

Firearms,

Why are you quoting me?

To show general agreement with the first sentence of your post and to answer the question in the second sentence of your post.

 

[Rule3]

To show general agreement with the first sentence of your post and to answer the question in the second sentence of your post.

Thank you, I was not sure, as you did not include the original post that I quoted so my statement was just kinda hanging out there. The second part was kinda rhetorical.
The quote of the quote, quoted or some such thing.

 

[firearmsunlimited]

Seating depth on revolvers and bottom feeders isn't rocket science. In fact is far less critical than with center fire rifles. The published COALs are based upon testing of numerous makes of guns - all of which have different clip, throat and leade dimensions. Even the SAAMI published specs that firearms manufactures follow for chambering have a max and min dimension. It is simple, find a COAL length that will cycle in your gun and work from that point. It is called load development. For those who seem obsessed with COAL and pressure issues buy an Oehler 43 and take pressure readings as you work to develop your pet load.

 

[Rule3]

Is the overall length shown in the reloading tables maximum, minimum, or nominal? And if it is nominal, what tolerance applies? +/-???

In God we trust. All others bring data!

As I was trying to relay what Hodgdons told me with their data. You are safe using their OAL down to their tested 1.200 (in this example I would say it's a min OAL) or whatever it is for a certain bullet from their min up to their max charge and not have problems.
The confusing part is that every manual has different test parameters, bullet, primer, barrel (test barrel or actual gun) temp, humidity and yes OAL. Lyman uses the MAX OAL for 45 Auto so their results will be different than say Hornady.

I just got done loading some Hornady 200 gr XTP for 45 Auto. The manual said load them at 1.230 OAL. But that length would not fit in one of my "pocket" 45"s. I had to reduce it to 1.200 for it to chamber and drop in and out of the barrel. I only used the min of 5.0 grs Bullseye so I am not concerned. So yes, there is room for adjusting OAL as OKFCO5 explained. Depends on what bullet and if you are at the high or low end. It also makes a bigger difference in higher pressure cartridges such as 9mm, 40 SW, 10MM and of course the barn burner revolver Magnums.

 

[blujax01]

Learning here and I do appreciate the patience as well as the good info.

Thanks!