Listed max OAL vs. actual max OAL

steveNChunter · July 16, 2013, 06:03 PM

How much difference should I expect in the max OAL measurement listed for a cartridge in a reloading manual vs. chambering an uncrimped dummy round and letting the rifling seat the bullet to give me an OAL measurement for my rifle?

For example, if my manual gives a max OAL of 2.825" and my chambered round measures 2.885", is that pretty normal or does it indicate some throat erosion? I realize the length of the bullet above the ogive is different for different bullets, but the OAL measurement in my manual for the bullet I'm using is the same as the max for the cartridge.

allaroundhunter · July 16, 2013, 06:19 PM

Typically that is just fine. I wouldn't try to determine throat erosion by the max OAL of a bullet. Even between 2 guns of the same make and model, neither will have the exact same max OAL.

PA-Joe · July 16, 2013, 06:33 PM

Also remember that COL may not feed correctly from the mag. A lot of times it is the mag length that is critial.

steveNChunter · July 16, 2013, 06:56 PM

I checked and that length actually feeds fine in my magazine.

That brings me to my next question. How much of a "jump" do you usually see the best accuracy with? I've heard of people loading anywhere from "touching the lands" to 0.080" or more off the lands. Is there usually a common range for most factory rifles? I know every rifle is different, just wondering if anyone with more experience than me has found a trend.

Most of the experience I have with my rifles show the best accuracy between 0.010-0.020

Brian Pfleuger · July 16, 2013, 07:10 PM

There is no standard "jump" for best accuracy. It could be anywhere from jammed in the rifling to as much as 0.250" out. Usually "closer is better" is somewhat true but not always.

As for your measurement, the answer is "Both". It could be normal, it could be from erosion, depending on your round count. Either way, it just "is". If you are getting a consistent measurement and you're technique is reasonable, it just is what it is.

dahermit · July 16, 2013, 07:17 PM

Quote:

As for your measurement, the answer is "Both". It could be normal, it could be from erosion, depending on your round count. Either way, it just "is". If you are getting a consistent measurement and you're technique is reasonable, it just is what it is.

Some rifles were notorious for excessive throat length. Had a Ruger "Liberty Model" .257 Roberts that had some much free bore, that it was almost impossible to touch the lands with any bullet. It seemed to be common at that time with Rugers and that chambering. Conventional wisdom of the time was to remove the barrel, take some off, re-chamber and re-install the barrel.

steveNChunter · July 16, 2013, 08:08 PM

Quote:

.257 Roberts

Funny you should mention that cartridge, the rifle in question in this thread is a 6mm rem which shares the same 7x57 Mauser parent case as the .257 Bob.

I don't know if my rifle is "notorious" for having a long throat or not, its a Remington 660 made in 1969. I don't know how many rounds its had through it, I recently traded for it. The bore looks almost like new so I assumed the round count was low. I haven't got a chance to work up a load for it yet, so I don't know how accurate it is.

If its inaccurate the action will be used for a build. I bet there aren't many custom rifles around built off a 600/660 action

BuckRub · July 16, 2013, 08:14 PM

Nothing is either this or that. My 30-06 is nearly .250 out some are tighter. Different barrels are cut deeper and some not nearly as much. Just shoot or reload to where you can shoot the most accurate.

July 16, 2013, 06:03 PM	#1
steveNChunter Senior Member Join Date: December 14, 2012 Location: Southern Appalachian Mtns Posts: 1,520	Listed max OAL vs. actual max OAL How much difference should I expect in the max OAL measurement listed for a cartridge in a reloading manual vs. chambering an uncrimped dummy round and letting the rifling seat the bullet to give me an OAL measurement for my rifle? For example, if my manual gives a max OAL of 2.825" and my chambered round measures 2.885", is that pretty normal or does it indicate some throat erosion? I realize the length of the bullet above the ogive is different for different bullets, but the OAL measurement in my manual for the bullet I'm using is the same as the max for the cartridge. __________________ DEO VINDICE

July 16, 2013, 06:19 PM	#2
allaroundhunter Senior Member Join Date: May 6, 2012 Location: Southeast Texas Posts: 1,670	Re: Listed max OAL vs. actual max OAL Typically that is just fine. I wouldn't try to determine throat erosion by the max OAL of a bullet. Even between 2 guns of the same make and model, neither will have the exact same max OAL.

July 16, 2013, 06:56 PM	#4
steveNChunter Senior Member Join Date: December 14, 2012 Location: Southern Appalachian Mtns Posts: 1,520	I checked and that length actually feeds fine in my magazine. That brings me to my next question. How much of a "jump" do you usually see the best accuracy with? I've heard of people loading anywhere from "touching the lands" to 0.080" or more off the lands. Is there usually a common range for most factory rifles? I know every rifle is different, just wondering if anyone with more experience than me has found a trend. Most of the experience I have with my rifles show the best accuracy between 0.010-0.020 __________________ DEO VINDICE

July 16, 2013, 07:10 PM	#5
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	There is no standard "jump" for best accuracy. It could be anywhere from jammed in the rifling to as much as 0.250" out. Usually "closer is better" is somewhat true but not always. As for your measurement, the answer is "Both". It could be normal, it could be from erosion, depending on your round count. Either way, it just "is". If you are getting a consistent measurement and you're technique is reasonable, it just is what it is. __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

July 16, 2013, 06:33 PM	#3
PA-Joe Senior Member Join Date: June 9, 2010 Location: NEPA Posts: 909	Also remember that COL may not feed correctly from the mag. A lot of times it is the mag length that is critial.

July 16, 2013, 08:14 PM	#8
BuckRub Junior member Join Date: October 3, 2012 Location: Central Texas Posts: 1,046	Nothing is either this or that. My 30-06 is nearly .250 out some are tighter. Different barrels are cut deeper and some not nearly as much. Just shoot or reload to where you can shoot the most accurate.