OAL Confusion

[webrx]

Hi all,

A little confusion on OAL here.

I am reloading for .243, the SAAMI specs say 2.540 min to 2.710 max for OAL

So, my understanding was that nominally all loads should be within this range and should work in any factory rifle.

Now I do understand you can do some measuring of your rifle chamber and work up to find more accurate, but I am just starting and basically wanting to build some rounds that will work for punching paper, and maybe some coyotes, rabbits, etc.

For my 65 grain Vmax loads the Hogdon COAL is 2.60 and within the band above, all good, they chamber, eject, etc.

For the 105 gr AMAX loads, Hogdon shows a COL of 2.760 which is longer than the SAAMI max OAL. I have not loaded a dummy round up yet to see if it fits the mag and chambers, but I will, I was just confused that this load exceeds the SAAMI max COAL - is this right or is it possibly a misprint?

Just so you know, I also double-checked in my Lyman 48 and it shows the OAL for a 105 jacketed AMAX at 2.710 (the SAAMI max) and it also shows the OAL for the 65 gr Vmax at 2.625 - slightly longer (.025) than hogdon shows on their site.

so do i load to SAAMI specs or the powder manufacturer, or the reloading manual?

Thanks

d

 

[thump_rrr]

I am assuming you are talking about the 243 Winchester and not the 243 WSSM.
Hornady 8th edition gives a COAL of 2.630" for the 105gr #24562 A-Max.
It also shows a COAL of 2.600" for the 65gr #22415 V-Max.
When using proprietary bullets I always use the bullet manufacturers data.

 

[witchhunter]

Load one as long as you can and see if it fits your magazine. Keep sizing it down until it does and measure it. This will be your max COL for your rifle if you want to use the magazine. To find your max COL for each bullet, seat one long, mark it with a sharpie and try to chamber it. Adjust your seater die until you do not see rifling marks on the bullet. This may take a few dummies to acheive the exact setting. Different bullet styles will have different COL to reach the lands. I start .020 off and go from there. This is where micrometer seaters are worth gold.
Start low and work up.

 

[webrx]

Thump_rrr, yes .243 Winchester. Yep, Both Hogdon and Lyman show the HDY AMAX bullet but now it looks like all three sources have a different COAL, at least 2 out of 3 are within SAAMI specs. Good thing we start low and work up huh?

Witchhunter, I will load one long and give it a try, as long as I dont crimp it, I would think when I chamber it I will find my max length for my chamber, are you saying to then decrease it .020 off that length as a starting point for accuracy?

I am assuming that if that is too long for the magazine then you go to max magazine length, or I suppose you could load one at a time if you want to use the longer bullet (closer to the lands) - correct assumption?

Sorry, for the questions, but I want to be sure I understand what you are saying as I have only been reloading a couple months. I am probably not going to experiment too much for a little while, but this is good info to file away when I do start loading for more accuracy.

thanks

d

 

[ants]

For your 243, the OAL listed in reloading data is just the length they used in the test. Nothing more. It's not necessarily a 'recommended' OAL. It's the OAL they used in the lab to get the pressure they report. It might be SAAMI, it might not. They are simply reporting the lab test length.

In handguns, loading shorter generally increases pressure. In bottleneck rifles it barely has much of an affect. So you can adjust OAL to suit your bottleneck rifle's magazine and chamber.

 

[jmr40]

I have no idea what the OAL is on any of my hand loads. I load them to fit the magazine first. Then I check for chamber fit. If they are so long the bullets are hitting the lands then I seat them a little shorter until they don't. This is where I find the best accuracy, but in rare cases they may need to go a bit shorter to get best accuracy.

 

[webrx]

Thanks Ants.

I understood about the OAL for load data being recommended, my confusion came in when it exceeded SAAMI specs as I thought SAAMI specs were the "min and max" standards and that all loads should be within these standards - meaning if within SAAMI then it will work and be safe in "off the shelf equipment".

I have only been reloading a couple months, so, I obviously have a lot to learn and see, but, this was the first time I have seen an OAL that was longer than SAAMI standards which brought about my confusion.

Dave

 

[witchhunter]

Web, make sure you adjust your die not to crimp when using the sharpie method. It's not necessary anyway. Also, no, when you chamber it, that won't necessarily be your COL, it should smash the bullet into the lands. Keep adjusting your die with a new dummy set at that length until you just don't see lands marking on your bullet. measure that. That is zero. Then go .020 shorter to start. start low and work up. Once you get it shooting good, then you can adjust the seating depth by .002 at a time, both directions to fine tune it.

 

[homatok]

Nosler #6 says SAAMI max length = 2.710! Hope that helps.

 

[webrx]

thanks again for all the info.

Lots to learn.

d