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Cartridge Max OAL

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21 December 2001, 17:26
<fa18hooker>
Cartridge Max OAL
I have read in numerous places how to measure a gun so that the round is just off the lands...but what if that length is greater than the Max OAL listed in the manuals? I'm reloading .308, and the max listed is 2.80". I loaded a dummy round in my Rem 700, and it's 2.95"...which would tell me to load 2.90" to get it off the lands. Is this right or am I way off?
21 December 2001, 17:45
<Bill>
Many handloaders often exceed the published maximum OAL. Assuming the fully assmebled cartridge will still fit into the rifles magazine and cycle, there shouldn't be any reason not to try this new length.

I have found the biggest factor limiting the length of rounds in certain guns to be the length of the magazine. Sometimes it does not allow you to get as close to the lands as you may want.

I have a little info about teh way I determine OAL here: www.rifleshooter.com/reloading/how_to_determine_oal.htm
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www.rifleshooter.com

[This message has been edited by Bill (edited 12-21-2001).]

21 December 2001, 17:48
<goneballistic>
Max OALs are listed to allow for functioning in all SAAMI spec firearms of that particular caliber, including Semi-autos.
When you custom load to your rifle, what you get is a custom load. Your cartridge may very well only fit your rifle. Also, longer OALs may not fit in your magazine.
Hopefully you are aware that different bullet types will have different max OALs and that measuring OAL from the bullet tip is not an accurate method.
21 December 2001, 17:56
Bob338
Max OAL describes two things, the standard length for that round per SAAMI specs and the OAL of the round as tested per the loading manuals. As long as the round feeds through your magazine you shouldn't have any problem so long as you have enough of the bullet in the neck to keep it straight and secure.

Seating on or near the lands is over rated. Many, many rifles shoot well with bullets being no where near the lands. Factory cchambered Weatherby's are a prime example. Conversely many shoot more accurately .015"-.025" off the lands. Harmonics of a barrel can be tuned by changing seating depth of bullets. You can find sweet spots way off the lands as well as near the lands. Vary the seating depths to get the best accuracy and merely use the distance to the lands as a reference point. Just concern yourself with straight and secure retention of the bullet in the case and whether at the OAL your barrel prefers it will cycle through the magazine.


21 December 2001, 18:26
<hotdog>
You have some very accurate and useful information in these posts. One thing I might add, do it both ways build a single shot load that will drive tacks. Then armed with this information build your hunting load with the thoughts towards the length of the magazine. If you go to turkey shoots, Get the box out that you have previously marked single shot winners. Just my .02 cents luck hotdog

[This message has been edited by hotdog (edited 12-21-2001).]

22 December 2001, 03:29
<bigcountry>
I tried to get close to the rifling also, using the stoney point setup, but couldn't match the harmonics of the barrel. My gun seems to shoot best when OAL is below SAAMI specs.
22 December 2001, 05:56
<Patrick>
You can find a clear discussion of OAL in the Nosler reloading manual. They suggest that greatest accuracy is often found with the bullet .025 off the lands. Each bullet is of course unique in it's shape and an OAL will have to be determined for each bullet in each rifle. They also discuss a procedure, which I use, for determining max length. good shooting.
22 December 2001, 07:41
John Frazer
I try for 0.030" off the lands, which is demonstrably more accurate than farther off in both of the rifles where I've experimented.

However, I temper that with the realities of gun functioning. My Mark X .30-06 can take loads seated just 0.020" above SAAMI max, but my VZ-24 Mauser barreled in .270 cannot feed SAAMI near-max OAL loads because its magazine box is too short.

Helpful hint of the day: find this out with a dummy round before (as I did) seating several bullets in live rounds and checking to see if they'll function. They went in easily enough but wouldn't come out. Since the military floorplate isn't made to open easily, I had to use a bent paperclip to hook them out.