OAL gauge for .260 Remington

[Unobogus]

Quick question. I am still very new to reloading and I just purchased a Hornady OAL gauge. I was trying it out just now on my .260 Remington. My manual says OAL is 2.800, but I keep coming up with 2.85, this time 2.8540. I know this isn't much to go on, but does that sound right? So, the manual is a "safe" OAL and my 2.85 is the OAL for my actual gun? I did measure some Black Hills factory ammo and it was 2.80.

Thanks for any help.
Craig

 

[Leo]

The bullet Ogive is generally supposed to be off of the lands. ,050" is pretty typical for a factory rifle. Squeeze them in until they are 2.800 OAL. Some will experiment and load a little long for accuracy reasons. If you eliminate all the freebore (jump) you can get a bad pressure spike. Many rifles will shoot well a 050 to .060" freebore.

WHile you are learning, stick by the specs until you get more experience.

 

[Unobogus]

OK, thanks. If I was wanting to know if I was using the OAL gauge correctly though, does that sound like it could/would be right? Could my guns chamber be 2.85?

 

[Leo]

OK, thanks. If I was wanting to know if I was using the OAL gauge correctly though, does that sound like it could/would be right? Could my guns chamber be 2.85?

Yes, you are likely using the gage system properly. The free bore or jump in the chamber would accomodate a 2.850 loaded round. Your magazine may or may not feed the extra length.

Does your gage system use the same bullet as you are loading, or does it have a it's own part that touches the barrel lands in your chamber?

 

[Leo]

OK, thanks. If I was wanting to know if I was using the OAL gauge correctly though, does that sound like it could/would be right? Could my guns chamber be 2.85?

Yes, you are likely using the gage system properly. The free bore or jump in the chamber would accomodate a 2.850 loaded round. Your magazine may or may not feed the extra length.

Does your gage system use the same bullet as you are loading, or does it have a it's own part that touches the barrel lands in your chamber? I like the one that uses the your own bullet as the center plug, as brand to brand bullets have slightly different profiles.

For accuracy and safety, the bullet major diameter (ogive) to lands relationship is more critical than the OAL.

 

[Unobogus]

Leo, thanks that is what i was wanting to know. Yes, the first time I tried it I used one of my Lapua 139gr bullets. I did use a comparator after I used the OAL gauge but again I'm trying to learn how to use both tools.

 

[dennymac]

You are using the OAL gage correctly. What you are seeing is the overall length of a cartridge loaded WITH THAT PARTICULAR BULLET that touches the lands in YOUR rifle. The factory OAL listed at 2.800 is the length that will go in EVERYONE'S rifle magazine.
Try a Scenar bullet, and see how long that round has to be to touch the lands. Again, in YOUR rifle. If you load longer than the published OAL, the rounds might not go into your magazine. Not a problem if you are OK with loading one round at a time. My .22-250 rounds are way too long to go in the magazine, but they shoot into nice little groups at long distances. Best of luck, and have a great day. DennyMac

 

[42769vette]

When I built my first 260, I planned it with a factory bottom metal. Day 1 I realized that would not be a good idea, and upgraded to an AI detachable mag. If I remember correctly (not necessarily a safe bet) For a 140 AMAX to touch the lands I would need right at 3.1". My factory bottom metal would allow for 2.85 overall length, the AI mag would allow for 2.97. Switching bottom metal allowed me to run a longer OAL without single feeding.

 

[Unobogus]

Thank you both for that info, it was exactly what I was looking for.
Vette, this might be a really dumb question but I have been looking for bottom metal for this gun. Would it be the same as .308? I can't find anything for .260.

 

[avboiler11]

What model rifle do you have?

A 139 Scenar on the lands at 2.85" seems like a fairly long freebore off the top of my head....with Alan's 260 having a mile of freebore if a 140 Amax is on the lands at over 3"...

 

[Unobogus]

700sps

 

[42769vette]

700sps

Yes its the same bottom metal as the 308.

 

[oldpink]

I have the Hornady OAL gauge that I use for each bullet that I load for my .30-06.
As others have noted, it's not going to work optimally to find a fixed COAL, then use that for all bullets in your caliber.
The SAAMI COAL of 2.80" is what the manufacturers have settled on as the agreed upon maximum length for uniformity of ammo, but you may well get a bit better performance and accuracy with your bullet seated out to a greater length just short of the beginning of the rifling.
Doing that will allow you just a bit more case capacity and a more uniform transition from the leade (unrifled portion of the chamber) to the rifling when the cartridge is fired.
You don't want to seat with the bullet touching the rifling because that can drastically raise your chamber pressure or cause problems (bullet pulled out of the case by the rifling and stuck in the chamber) if you should need to take out a round without firing.
It's best to seat the bullet a short distance from the rifling (I make it a practice to seat all my bullets to just 0.100" of what my Hornady OAL gauge shows as max), and another very good practice to greatly speed up your seating plug setup is to make up a dummy round of each bullet you intend to load.
I have a dummy round for each bullet I have loaded in my rifle, with the exact bullet (e.g. Sierra 180 grain Pro-Hunter spitzer) and COAL written on the case in Sharpie.
When it comes time to seat a given bullet that I've loaded before, I just put that dummy round for that particular bullet under the seater die with the ram all the way up, then turn down the seater stem until it rests firmly against the bullet.
I then seat my first live round that way, then measure it to see how far off it is from my COAL written on my dummy round.
Invariably, that first live round will be a bit too long, so I turn in the seater stem one turn, then put that first live round back in and raise the ram to nudge the bullet in just a bit more, lower the ram, then measure the length again, repeating the process until I finally reach the correct length, then lock down the seater stem.
After that, I just seat the rest of the rounds I intend to make with that bullet.
I can tell you that all of the bullets (it's somewhere around two dozen different ones) that I have loaded in my .30-06 are seated out just a bit longer than SAAMI spec.
Something else to consider with COAL is (of course) your magazine length, which could possibly limit your COAL because it's impractical to have cartridges that fit your chamber, but that don't fit your magazine.
I've loaded only one bullet that could be seated out far enough that it won't work through the magazine, the 165 grain Nosler Ballistic Tip; therefore, I seat that particular bullet to as long as I can while still functioning reliably through the magazine.

 

[Unobogus]

Great, thanks. That is what I was thinking but I like to have conformation right now on most of the things that I'm doing while trying to learn the basics.

 

[Jdubbs]

I ran into a problem when i got my hornady oal gauge. I was using everglades bullets and would have fliers intermittently. I thought it was bad bullet quality. I weighed each one and found them all to be within .5 grain which is good enough for me. I then checked bullets using the comparator and found that the ogive measurement was off on some, about 1 out of 10. So loading all of the rounds to the same coal was dead on, but the jump was different from one to the other due to the ogive differences. So now when i reload i have 2 calipers setup so i can check my coal as well as my ogive measument to the base. I opt to keep my ohive measurements the same for accuracy, and cheat on the coal in order to do so. This also tightened up my groups tremendously.

 

[Unobogus]

jdubb, thanks for the info. That's what I'm trying to do, make the best ammo for my gun, I just wanted to make sure that I had some room to give on the coal.