beginner question case overall length

[billetmann]

i am new to reloading-- just started last night.
i am loading 30-06, read the manual many times then started -everything went smooth and easy -made sure to check and recheck each step along the way.

question is when i read that the overall length was shown as 3.31. (in manual)

i seated the bullet in the case to 3.310 (using a dummy one first) but this length seemed extrememly long. so i measured some stock factory ammo and the lengths from box to box differed-- some 3.195, 3.208, and 3.180

if i set the length to 3.250 is this okay? - and will this be a point where accuracy is played with?-trying different lengths to see what my rilfe likes.

[Sub95]

what bullet? whats the bullet weight, what powder are you using?

[damndave]

I do not know the lengths of 30-06 since I do not reload it.

I use a Hornady comparator to measure from the ogive. It's a way better reading on the distance from the ogive to the lands of your barrel.

Bullet lengths vary a lot. Some of mine vary up to .010 in OAL. When I started measuring from the ogive that went down to about .002

[thunderbolt]

I'm kinda new to this too but this is how it was explained to me. (Someone step in if I'm wrong please) If you're reloading for a bolt action the easiest, but least accurate, way to find your rifles perfect COL is to loosly seat a bullet (sans powder/primer) and firmly and slowly close the bolt. Eject the cartridge and measure. There should be some marks on the bullet from the rifeling. Back that off a hundreth or so and set your seating die. Accuracy can be affected by the "jump" between the smooth chamber and where the rifleing starts.

For a semi-auto set your COL to your magazine specs with regard to reliable operation.

I've found my four reloading manuals call for 6 different COLs and in the case of my AR they all called for a COL of 2.200 which was .05" shorter than the ammo I was duplicating and a whole .06" shorter than the max COL. I was told that was just a starting point and since chamber depths and specs can vary wildly even in the same caliber that the published COL is more of a guideline than a rule. Good luck and don't blow yourself up.

[billetmann]

the bullet is a nosler partition 150 GR --powder i am using imr4895

[billetmann]

so the cartridge overall length shoudl be set with each gun and not really the published value-correct? i imagine the published value is just going to be the safe max.

[billetmann]

so i need to find a hornady comparator and see how it works out

[popeye4]

The COL specified in the manuals is to ensure that a standard round fits in a standard magazine. If you are shooting short bullets (like some of those 130 gr ones), you might not get enough contact in the neck area to hold the bullet securely if you try to meet max length. But if you are shooting longish bullets, like the heavier match grade ones, you might have to seat the bullet deeper into the case than you'd like if you need to fit the magazine. In a hunting rifle, it usually isn't a big deal, but for high accuracy rounds (particularly those that will be loaded directly into the chamber and not run through the magazine), it is sometimes beneficial to seat the bullet close to the rifling. That is a more advanced topic, though, one that can get you in trouble with pressure spikes if you aren't careful or knowledgeable.

As Allied stated, measuring from the ogive (at the diameter that first contacts the rifling) is the most consistent way to determine how far the bullet is from the lands, and that is the dimension you should use to set the seating depth of your bullets (hopefully the seater in your die doesn't push on the bullet tip). But if you are loading to magazine limits, the COL is also important, at least from the standpoint that all your rounds must be less than the upper limit so they don't jam up in the mag (the COL may vary somewhat, depending on the consistency of the bullet ogive to tip measurement). So sometimes it becomes a trade-off between reliability (fitting the mag) and ultimate accuracy.

[billetmann]

i just found and article at Larry Willis.com that gave a great answer

http://www.larrywillis.com/OAL.html

thanks for the help.

[rumblebee]

good article! I used a dremel with a small disc cutting wheel to slot out the neck of a .223 and .308 case (not too much, as you do want some resistance) and it works pretty good.

i just found and article at Larry Willis.com that gave a great answer

http://www.larrywillis.com/OAL.html

thanks for the help.

[Sub95]

so the cartridge overall length shoudl be set with each gun and not really the published value-correct? i imagine the published value is just going to be the safe max.

correct on both. but for plinking you can just use the published data.


Max. OAL: 3.340" nosler partition 150 GR from Nosler site.


off of hodgdon site 30-06

150 GR. NOS BT IMR IMR 4895 .308" oal: 3.250" grs49.0 fps2856 49,400 PSI grs53.0 fps3009 56,700 PSI

[Whiterabbit]

You've already got your answer, but yes, there's no such thing as a too-long OAL. only too small. Some of the long range shooter guys get so crazy with bullet seating that they will seat the bullet too shallow for the feed ramp, and watch out for bullets falling out in the chamber and spilling powder all over the place.

Don't take my word for it, here's what a professional has said (when I emailed them asking about it)

"Outside of looking silly there is no problem with that load. The SAAMI max is actually for factory ammo. And does not really apply to the hand loader. So long as it shoots well and fits in the magazine you have nothing to worry about. "

The folks at the long distance shooting websites seat farther than magazine length and shoot them one at a time.

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BTW this is all based on 30-06, not pistol rounds.