min. OAL

[SSN Vet]

just blew the dust off my reloading bech (desk actually) and set up shop in our finished (and heated ) basement office. This is a HUGE improvement.....thanks to my wonderful wife

Also, just loaded my first batches of .223 and 7.62x39 and now have a question concerning min. OAL. I want to make sure I understand the "why" behind this limit.

Q1: Am I correct to say that purpose of the the min. OAL is to prevent a compressed load?

Q2: Is there another purpose for min. OAL?

With my .310 125 gr FMJ bulk bullets from Wideners, the crimp groove is not shaped like the cannalure band I'm used to seeing. It actually looks like it may be a pulled mil. surp. bullet, and that the crimp groove is really just a "dent" left over from crimping onto a non-canalure bullet.

If I seat to the level of this dent, I will be ~.01 shorter than the min. OAL listed in my manual.

However, I'm only dropping a med. charge (24.8 gr of 1680) and there appears to be adequate room in the case to seet the bullet to the "dent" and not compress the load.

Q3: If I do this and I can still pass the "shake-ah shake-ah" test (After seating and crimping, I can hear the powder shaking in the case), am I good to go?

Just when ya get to the point where you think you actually know something, ya start loading a different caliber and generate a whole new set of questions.

I can see why this "hobby" can keep guys interested for years and years.

 

[ranger335v]

I started reloading in '65. NO books of the period indicated any OAL lengths then, just max lengths for cases, and no one I ever knew or heard of blew anything up because of it.

We just followed the rest of the books instructions, seat so the cartridge will feed and not jam bullets into the rifleing. Using what ever cases we had, and what ever bullet of a given weight, we THEN developed our loads, checking for pressure signs to say stop until we reached the max suggested charges. It was a safe way to work because anything that might influence pressure was taken into account by the process of building up until any excess pressure signs appeared.

Only recently have books started to include the OAL lengths used to develop their loads, it's not a precise SAMMI length that must be followed any more than the suggested charges are. That OAL info was meant to help but it seems to have caused more confusion than anything else every printed. It needn't be so.

Develop your load. Then, if you change ANYTHING, back off a little and only work back up if conditions permit and you will be safe. That includes OAL.

I don't trust "shaka-shaka" at all. I visually check EVERY case for a consistant powder column before seating. I can't do that with a progressive, so it's part of why I won't use a progressive!

 

[rcmodel]

The is no hard & fast "shaka-shaka" test.

Compressed loads are perfectly normal with some powders & loads.

There is nothing at all dangerous about a compressed load, as long as it is supposed to be compressed, and it weighs what it is supposed to weigh, according to the tested load data.


If you are not using specific load data for a specific brand of bullet, which apparently you are not, you can seat the bullet to the old crimp dents, or seat to the recommended OAL for another bullet of similiar shape & weight.

As long as you are not loading a Max Load for another brand of bullet, you should be fine.

The recommended seating depth has more to do with fitting in any magazine & feeding properly then any actual need for an exact OAL to maintain load safety.

Of course it is also telling you what OAL was used to test the loads in the first place.
But it only becomes critical from a safety standpoint at Max charge levels.

rcmodel

 

[Ol` Joe]

I believe most min OAL lenghts are the lenght the cartridge will function properly at in most actions, although seating too deep can also raise pressure due to reducing the chamber volume.
The crimp can vary in placement depending on the cartridge the bullet was developed for. A bullet designed for the 30-06 will have a crimp groove in a different place then one made to fit a 30-30. If you are loading for a semauto or otherwise need a crimp you will have to pretty much make do with the placement already on the bullet.Your reloading manual should cover most of this to a point.
Just because you can hear powder shake in the loaded round means absolutly nothing as far as safety!

 

[SSN Vet]

There is nothing at all dangerous about a compressed load, as long as it is supposed to be compressed

That's why I was shaking them....Modern Reloading II specifically tells you in the table if it's intended to be a compressed load. This load is not intended to be compressed....so I figured that perhaps I could seat deeper, provided the powder was still mobile.

I'm well below max. so I figured the volume of the void space wasn't going to be to critical

I loaded 20 last night at the min. OAL in the table, and crimped into the jacket below the existing dent.

I'll try to post some pics and see what the consensus is, as to whether or not these are pulled mil. surps or not.

These are plinkers for an AK....not woking up for accuracy for this bullet. Just trying to get enough rounds down range to get proficient with the rifle and it's 'lovely' sights.

 

[rcmodel]

But my point was that compressing a load, any load, doesn't make the powder go off with any more energy at all.

It only has so much energy available for a given weight of powder, and it doesn't increase in energy if it is compressed.

What changes with deep seating is the internal case capacity of the loaded round.
Less space = more pressure.

But the compressed load isn't any more powerful in stored energy then if it wasn't compressed.

rcmodel