All:



I'm loading some .270 Win with 140gr Nosler ballistic tips.  According to the Nosler reloading guide, the maximum overall length of the .270 Win cartridge is 3.340.  Does that mean that the round loaded with the 140gr Nosler has to be exactly that length?  What about a minimum cartridge length?  I assumed that there would be some small range that would be acceptable without increased pressure being a problem.  If I were loading 160gr Noslers wouldn't the base of the bullet be farther into the case to maintain a total OAL of 3.340?  Help a noob out.



AV1611

The max COAL is a general number. So for instance 3.340" is probably the longest you can load that will fit in most box magazines. Could you load longer for a single shot rifle? Absolutely. Can you load shorter, sure.

Generally with rifle it's acceptable for COAL to be shorter, as it doesn't cause pressure increase/spikes.

Not the same with pistol however.

Find a COAL that works for you, and stick with it. I would personally start at mid-cannelure.

The .270 cal 140 gr Nosler ballistic tip has no cannelure.



AV1611

The only dumb question is one not asked.  If loading rifle I suggest getting the Hornady Overall length gauge Midway to determine where your rifle lands are with a given

bullet. Most start 0.015 - 0.030 off the lands and adjust from there after they have found a load that works (if you don't know what I'm talking about read about bullet seating depth in rifle).

Most the time, rifle seating depth will be longer than factory loaded ammo as factory ammo has to work in all manufacture's chambers.

Also, I suggest reading the tacked threads above and picking up a couple of reloading manuals and read the front sections.  The ABC's of reloading is a must for new reloaders along with one

or two of the following: Lyman 49, Hornady 8, Nosler 7, Sierra 5th(or 6th don't remember which I have).

Lyman 49th edition has a 140gr Hornady BTSP loaded at 3.335" and a Nosler 160gr SP at 3.340"

I don't feel I have enough experience to speak authoritatively on this, but thinking about a reply was helpful for me and may help some others.

There seem to be four possibilities when you select seating depth:
1) If the bullet has a cannelure you should strongly consider using that as a guide to the seating depth.

2) Seat the bullet close to where it engages with the lands. This is dependent on your chamber and magazine length or willingness to single load. This is where the seating depth is most critical and complex measuring procedures / tools are required. A commercial chamber will rarely have this occur below or anywhere near magazine length. People do it because it often provides benefits for accuracy.

3) Seat so it is just under magazine length. This is what I default to. For safety and function you should check on a few things. Make up a dummy round and seat the bullet out long to verify that it does not engage the lands when you chamber it. Then check if you have sufficient engagement between the bullet and case neck; be cautious about leaving any of the neck without the large diameter of the bullet to grab onto. Third you should check your COL on a large sample of the rounds you load to verify the seating depth is sufficient. Often there are length differences between the tip of the bullet and the section that the seating die engages. The first round you seat may be perfect, but you will find out at the range that others don't fit.

4) The last possibility is seating below magazine length because it is a short bullet. When the bullet is not sufficiently engaged with the case neck, then it needs to move back until it does.

The reloading manual should give a recommended COL for every bullet they list. This is a good guideline to follow, but keep in mind they are sometimes determined with consideration for magazine length, which may not be applicable for you. Also they may indicate some loads will be compressed charges at the max load. That is only applicable if you use their COL. Shorter COL may cause other loads to be compressed charges as well.

Does Nosler have a recommendation in their data?

Nope.  Just an OAL for the finished cartridge.  

depends on the barrel. if you have a long throat then you may want more or less jump to the lands/grooves.

No.  I was asking because it sounded strange that there wouldn't be an acceptable OAL range seeing Nosler makes different projectile lengths and weights for .270 cal rounds and only lists one OAL for a .270 Win loaded cartridge.



AV1611



       




 

 Nosler manuals, #6 for example did not list the OAL/COAL used during their testing.  Instead they instructed the Handloader to find the Max OAL for "THEIR" rifle and go from their.  Here is what Nosler #6 recommends for OAL/COAL.



Accurate/Ramshot has also been kind enough to include this little helpful tip on OAL/COAL.

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a
guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of the barrel, 3)
ogive or profile of the projectile and 4) position of cannelure or crimp groove.