COL vs Max COL

[mugsie]

As some of you know - I'm relatively new to reloading. Reading the posts has really gotten me confused. I'm using a Speer manual to load 38 and 357. In the manual, they list a bullet weight and a COL that that particular bullet (Speers) was seated to along with the corosponding powder load. As part of the header information at the beginnig of each section, they also mention MAX Length. For instance (the numbers are hypothetical since the manual's down stairs and I'm too lazy to walk down and get it!). They might say 158 JHP, 4.3 grains Unique, COL 1.450. In the header section they'll indicate Max CL 1.55". Does this mean that I can seat the bullet anywhere between the 1.45 and 1.55 as long as the bullet chambers properly? :banghead:

I'm using Berrys RN bullets, and of course Speer doesn't have a listing for Berrys, so I'm taking an equivilant bullet and using that data. Berrys is plated very lightly so it's similar to plain ol' lead. I tried varying the seating depth to see what affect it would have on accuracy and found that the ones seated slightly further out (at the hypothetical 1.55 Max length) had slightly better consistancy.

All shot fine with no visible pressure symptons.

 

[taliv]

you can put the OAL pretty much anywhere you want depending on several things.

first, know that if you move it in, it can raise the pressure. the load listed shows the OAL that speer chose to use that resulted in the specific pressure they list. if you load it further in, it could be higher pressure. if you load it out, it might be lower, but probably not.

second, if you move it out, it will eventually touch the "lands" or the rifling. this isn't necessarily bad, as lots of benchrest, bolt-gun shooters think this is the way to maximize accuracy. however, it generally results in more pressure, so if you're at the max, seating it out too far could give you serious grief.

also, you probably wouldn't want to do that in a non-benchrest rifle because if for some reason, you decide not to pull the trigger, and need to unload the weapon, the bullet might stick, and you'll end up with a load of powder in your action. highly annoying.

also also, you probably wouldn't want to load too far out because you may have feeding issues in the magazine or going into the chamber. (too far in could also result in feeding issues in something like a pistol)

also, also also, you probably wouldn't want to load too far out because you might not have enough neck tension to keep the bullet in place under recoil, in the event you're shooting other than a single-shot.

there are plenty of other reasons not to go too far out or in, but the cartridge dimensions should give you the range, while the sample load from speer will give you a starting point.

 

[Bullet]

mugsie Quote – “I'm using a Speer manual to load 38 and 357.
Does this mean that I can seat the bullet anywhere between the 1.45 and 1.55 as long as the bullet chambers properly?”

Yes, but if you seat to the MAX OAL(1.55) and are using a MAX powder charge, reducing OAL (1.45) will increase pressure above MAX. So my advice would be to work up your powder charge at the MIN OAL (1.45) and then increase OAL if you want. This is for handguns only. Rifles are a different story as taliv explains above.

 

[Ol` Joe]

The max OAL listed in the header is the max lenght SAAMI has set for that cartridge. All ammo made for this cartridge will be loaded to or below this lenght by the factory. The ammo is also of a lenght that it will fit all pistols (or rifles) chambered for it with a SAAMI reconized chamber and the magazines of the same guns..
The OAL listed in the data section is the lenght loaded to by the manuals authors when working up the load. This is the OAL you want to use if you plan on repeting the results the lab boys found. Change the listed loaded OAL and you change the load, same as varying the primer or case brand. The change may or may not change the pressure you get from the load. The only way to tell is measure it if you have the means.......
Work up if you do vary the books OAL in your loads.

 

[Bullet]

Ol` Joe

I thought reducing case capacity increases pressure when using listed loads. Are there exceptions to this?

 

[Ol` Joe]

I thought reducing case capacity increases pressure when using listed loads. Are there exceptions to this?

With rifle loads that were developed with the bullet at, or in the lands, when one reduces the COL it can reduce pressure. This acts like adding free bore to the rifle, similar to Weatherbys long throating. Normally reduceing case volume by seating deeper raises pressure. Hornady has a little on this in their manual. They show it though as increasing the lenght adding pressure, instead of reducing the COL lowering it.

I, and quite a few other reloaders I know, start load work up with the bullet touching the lands for our rifles. Once we find our max load this way we can reduce the COL looking for the jump the rifle prefers for best accuracy without worrying about pressures increasing. With the large cases the little decrease in volume is off set by the bullet getting a running start at the lands. Pistols with their smaller cases are more susecptable to the volume decrease. The reduction of 2 gr of space in a pistol case that holds 10 gr of water is much less then removing the same amount from a rifle case that holds 70 gr, percentage wise.

A real good book on pressure and things that effect it, that every handloader should read is A`Squares "Any Shot You Want". It is very limited on data and only has rifle loads but the discussion on pressure and lab results from changing things, primer, case, COl, ect is priceless.

 

[Bullet]

Ol` Joe

I’m sorry I didn’t make myself clear. I was referring to mugsie’s 38/357 reloads, but since I didn’t clarify my question I believe you are right about the lands.

So I’ll try again. If you’re reloading for a handgun with the bullets seated off the lands, I thought reducing case capacity increases pressure when using listed loads.
Are there exceptions to this?

 

[mugsie]

Thanks everyone

I knew I could get decent advice here! Thanks guys for the information. I'm doing it correctly I guess. I was attempting to duplicate the Speer data for a particular bullet, however I noticed on the Berrys bullets, when loaded to the Speed equivilent, I was crimping on the ogive. When I left the bullet out a little further, still within the Max OAL, I crimped on a flat and I was having better results at the range. I was always within the Max OAL and never saw pressure problems, but I just wanted to hear from some more experienced members as well. Nothing like listening and learning.
Thanks again....