OK todays dumb question....


PDA






poor man
February 22, 2013, 11:47 AM
with all the talk of COAL and OAL and so on ... HOW does anybody buy store ammo and fire it safely??? people are telling me i need to check the OAL to be safe for my gun, what about the store ammo?? i went and drug out some store ammo from different company's and mic'ed it...WOW it was all over the chart. same grain ammo same style bullet and the OAL was all over, so how can this be safe to shoot???? thanks

If you enjoyed reading about "OK todays dumb question...." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
rcmodel
February 22, 2013, 11:56 AM
Store ammo is loaded to a minimum SAAMI length to work in any SAAMI spec chamber.

Your reloads often use bullet profiles you don't see in commercial ammo, and aren't SAAMI minimum length to fit any chamber until you make it so with testing in your chamber.

rc

bds
February 22, 2013, 12:18 PM
It's not the length of the bullet tip but the bearing surface (part of bullet base that rides the rifling) that determines whether the finished round will fully chamber in your factory barrel which should be within SAAMI specification.

Ammunition manufacturers will load their bullets so the bearing surfaces of the finished rounds will clear the start of rifling in factory barrels. When we reload, we need to do the same by conducting barrel drop test to ensure the rounds drop in the chamber freely with a "plonk" and spin without hitting the rifling which is the Max OAL.

Once we determine the Max OAL, next we need to determine the working OAL that will work with our pistol/barrel/magazine by feeding/chambering from the magazine and releasing the slide. Working OAL is sometimes the same as Max OAL and sometimes shorter.

Like factory ammunition, depending on the nose profile (ogive) and the bearing surface of the bullets, working OAL may vary depending on the bullet manufacturer.

Of course, once we determine the OAL that works with our pistols, we then proceed to powder work up to identify the powder charges that will reliably cycle the slide, extract/eject the spent cases, feed/chamber the next round in the magazine and produce accurate shot groups.

Jesse Heywood
February 22, 2013, 12:21 PM
Semi auto ammo is manufactured to the "one size fits all" principal, which is the SAAMI minimum as stated by RC.

When you load you are tailoring the round to fit your gun(s). You're not usually concerned about if your ammo will work in my guns. The OAL is there to maintain a standard for the cartridge pressure. The manufacturers test their pressures for the minimum length, we usually load near the maximum length.

Magnum Shooter
February 22, 2013, 12:46 PM
WOW it was all over the chart. same grain ammo same style bullet and the OAL was all over, so how can this be safe to shoot???? thanks

As far as safety is concerned it is not the OAL that maters, it is the seating depth that makes a difference.

poor man
February 22, 2013, 01:05 PM
thanks, that helps understand things better, im going to print this and put it with the other books and info i have been inquiring, i have decided to stop loading anything right now until i understand more about it..... the "old" loads i have been doing were checked by my "mentor" (who is gone now) so i know i can load them safe BUT no new loads until i learn,,,


thanks for all the help

Trent
February 23, 2013, 12:56 AM
Remember the only stupid question is one that is unasked.

So when you have questions, come back and ask. :)

Lost Sheep
February 23, 2013, 01:12 AM
As far as safety is concerned it is not the OAL that maters, it is the seating depth that makes a difference.
More to the point, it is the free volume under the bullet that is important. More volume, all other things being equal, less pressure. Less volume, more pressure.

Since we cannot measure the volume under the bullet, or even the linear distance from the case web to the bullet base (assuming a flat base), we depend on the cartridge length as a proxy to the measurement we wish to control.

Since the ammunition makers know the bullet length and shape and have signed on to the (voluntary) S.A.M.M.I. specifications, they (in theory) take into account stuff many handloaders take on faith (how many of us measure the length of a bullet, the depth of the web of all our different brands of brass and subtract that from the Cartridge OAL?).

Much less, how many of us pay attention to the chamber dimensions of the test guns from which the loading manuals derived their data, even if that information were available?

Rather than pick over the details, we watch our own brass, primers, leading and other diagnostics to see how much pressure our particular guns generate. This is why we start low and work up.

Be safe, always, all ways.

Lost Sheep

James2
February 23, 2013, 01:53 AM
Here is what I recommend:

First, once again read the how to steps in your manual.

Pick a load from near the low end of the chart, and use the COL that is given with the load. Check that it will work in the magazine, and pass the plunk test. (or in a revolver, that it does not protrude out the front) Make a few. Now test fire it. Work up from there. A little more powder at a time. Test fire. etc. Don't make a whole bunch until you have a load you like.

Yes, there are some accuracy things and pressure things associated with seating depth, but for your purposes now starting to learn, it is not important to worry about as long as you use a published load, start low and work up looking for signs of high pressure.

The COL given with the load is a safe place to start using a powder charge from the low end of the chart. Once you master the basics, you may want to play with seating depth for accuracy reasons.

Never mind what length the factory ammo is. It has no bearing at all on your loads. Enough has been said about SAAMI spec.

Fire_Moose
February 23, 2013, 02:38 AM
You can measure web thickness....

Get a couple inches of dowel that will fit inside a case.

Zero calipers with the dowel between the jaws.

Slip case over one end and measure.

;)

Sent from my CZ85 Combat

poor man
February 23, 2013, 10:20 AM
Thanks again...

ArchAngelCD
February 23, 2013, 10:31 AM
No need to stop loading although I like the fact you are willing to do so for safety reasons.

I have a suggestion that will calm your safety suggestions. While not usually necessary if you buy and load the same exact components used in the load manual you can feel safe the load is safe. The OAL in the book is for the exact bullet they used in testing that load so if you use the same bullet you can be confident in their listed OAL. If you must you can even use the same brass and primers but that's going a little too far IMO. As long as you start low and work up you will be perfectly safe.

Don't give up because of worrying especially since you have already loaded ammo in the past with good success.

poor man
February 23, 2013, 10:50 AM
thanks, im not giving up im just putting it on hold till i get the rest of my manuals and learn more about what im doing.....

blarby
February 23, 2013, 10:56 AM
The only "dumb" or "stupid" question is the one you already know the answer to, or don't want to hear- respectively :D


Factory ammo is mass produced using varying bullet seating machines, on varied production lines.

Combine that with bullets that aren't 100% either, and you are bound to have great differences in OAL.

Now, try measuring some by their Ogive length- I think you will find the differences less severe- but still more pronounced than what a meticulous handloader would aim for.

Factory ammo, as stated, just has to fit and fire- not much else.

RandyP
February 23, 2013, 11:40 AM
I am speaking ONLY about reloading to the mid point of published data here (which is MY personal preference).

There can be an substantial amount of 'tolerance' in data numbers for OAL and charge weight while at the same time making perfectly safe, accurate and reliable reloads.

Reloading need not be rocket surgery unless the individual reloader wants it to be. IMHO there is such a thing as 'close enough' and my reloads would not really benefit on a practical use level from trying to measure and weigh everything to the 4th decimal place. I get more than adequate results using my $10 Harbor Freight calipers and my $30 MTM digital scale to let me reload safely and enjoy the hobby. That works for ME. Others may only be satisfied measuring to the gnat's eyelash level with very expensive tools and that's great and works for them. I only gotta keep me happy.

I DO want to stress that I am NOT advocating for sloppy reloading procedures. I weigh and measure my die setups and powder throws, I make regular spots checks during the reloading process. I find my Lee gear gives great consistency with my powder of choice Win231/HP-38 and the die setups remain rock solid. I do not however fret over very minor variances.

Lost Sheep
February 23, 2013, 01:32 PM
You can measure web thickness....

Get a couple inches of dowel that will fit inside a case.

Zero calipers with the dowel between the jaws.

Slip case over one end and measure.

;)

Sent from my CZ85 Combat
Better yet, weight the empty case. Fill the case with water to the depth where the base of the bullet will be. If the bullet has a hollow base, fill the base with water and figure out the weight of that water.

There are many, many ways to figure the volume inside a cartridge.

Once you have done this with the components that were used to produce the data in your manual, you know the volume that particular ballistics lab had.

Then you do the same thing with the components you are using.

Compare the two volumes.

Adjust your seating depth or powder calculations accordingly.

I believe you will find that the difference (if you are in the mid to low range of the published data) is not enough to worry over for safety concerns. S.A.M.M.I. specifications keep all components pretty close to the same.

Note that almost no handloaders are so fanatical to go through the water-weighing process. Most find weighing the brass to be an adequate control. While the weight of the brass does not tell you anything about the relative volume of your components vs the lab's components, selecting all YOUR brass to be the same weight does keep your volume consistent, cartridge to cartridge, and that is enough for accuracy. Starting low and working up takes care of the safety.

James2 (post #9) is right.

Lost Sheep

Trent
February 23, 2013, 01:44 PM
My opinion is that unless you're doing benchrest shooting, and care about getting another .01 MOA, weighing cases is pretty much a waste of time.

If you enjoyed reading about "OK todays dumb question...." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!