Case OAL Tolerance

[HighDesertSage]

What do you guys who have been reloading for awhile consider to be an acceptable OACL variation from road to round. I was thinking +/- .005 is acceptable for rifle cartridges. Thoughts?

 

[Fire_9]

Are you measuring to the tip or the ogive?

 

[Pelican]

+/- 0.005 seems excessive to me. If you really want to know what matters, test them in your gun. Shoot multiple groups with ammo that is +/- .005 vs ammo that is +/- .001. That will tell you if it is important in your gun with that load. I was fortunate to know a lot of serious shooters when I was younger and learned that the only way to really know what matters is to test it. What works great in one rifle, may not work in another.

 

[HighDesertSage]

tip

 

[Fire_9]

You’re going to see some variance when you measure to the tip. Get yourself a kit to measure off the ogive

 

[Bigjay73]

Yeah, measuring to the tip will never be consistent. All bullets will have varying lengths from tip to base. As fire9 said, get a kit. Hornady makes an acceptable one.

 

[VikingsGuy]

If you get a a kit (hornady makes a decent one) to measure from ogive, and have decent loading equipment and technique, +/- 0.001 is fairly simple.

 

[88man]

yes as all have said get the oal comparitor and measure from the ogive

 

[Don Fischer]

I don't measure OAL to the ogive, don't know anyone that does. Generally OAL is measured to keep the case mouth from entering to lands and raising pressure! But for re-sizing and making the case work in the chamber with the OAL in limit's, I use the chamber of the rifle to determine if the case fit's properly. I neck size with FL dies two or three time's till the case will no longer allow the action to close. Then I FL the case down a little at a time till the action close's without rubbing on the shoulder, partial sizing. At that point the case fit's your chamber. That FL die is locked in right there and dedicated to that rifle only. From then on, that dies will always size a case to fit that rifle and to heck with all that measuring. I suppose it's nice to be able to tell someone the actual size of your chamber from bolt face to ogive but it serve's no useful purpose at all.

 

[Fire_9]

I don't measure OAL to the ogive, don't know anyone that does. Generally OAL is measured to keep the case mouth from entering to lands and raising pressure! But for re-sizing and making the case work in the chamber with the OAL in limit's, I use the chamber of the rifle to determine if the case fit's properly. I neck size with FL dies two or three time's till the case will no longer allow the action to close. Then I FL the case down a little at a time till the action close's without rubbing on the shoulder, partial sizing. At that point the case fit's your chamber. That FL die is locked in right there and dedicated to that rifle only. From then on, that dies will always size a case to fit that rifle and to heck with all that measuring. I suppose it's nice to be able to tell someone the actual size of your chamber from bolt face to ogive but it serve's no useful purpose at all.

You are way out in left field on this one. He’s not talking about measuring to the shoulder, he’s talking about measuring the length of a loaded cartridge. Measuring to the ogive gives you the most accurate and most important measurement when determining seating depth.

 

[Schism]

You are way out in left field on this one. He’s not talking about measuring to the shoulder, he’s talking about measuring the length of a loaded cartridge. Measuring to the ogive gives you the most accurate and most important measurement when determining seating depth.

Exactly!

To the OP,

I am a nerd and like to have my own information so I kept some records on OAL length variances in my hand loads. When measuring from the tip of plastic bullets there wasn't much variation (0.002-0.003") within a single lot, but when measured between lots I've seen 0.010" before. On soft point or hollow point bullets the OAL length when measuring from the tip can easily be 0.010" within the same lot.

When measuring from the ogive I regularly have variances of 0.001-0.002" within, and between lots of bullets. For me this is acceptable.

Measuring OAL to the tip is only relevant to me when trying to run at or near magazine length. Even then, I will find a measurement that is suitable to fit the magazine based on ogive, and not the tip of the bullet due to the variances described above.

FWIW I use a Rock Chucker or Dillon press and Redding or RCBS dies on all my hand loads.