Help on CBTO

[RSBrown]

Trying to find the CBTO measurement for my rifles. I have the Hornady OAL gauge, the correct collars for the bullet diameter and the modified Hornady cases. The measurements I am getting on three different 308 bullets in my Remington 700 are all longer than the recommended OAL and the bullet is barely into my brass.

What am I doing wrong or forgetting to do? The measurements themselves are within .005 across 10 samples of each bullet. Any thoughts?

 

[Twitch2120]

Nothing. Factory chambers are oversized. Once you have a CBTO measurement the only other measurement that matters is mag length. If it still fits/functions then run it like you stole it. Max OAL in the books is just the sammi spec that ensures proper feeding from mags.

 

[Callison]

sounds like you are measuring to the lands of your rifles and finding the bullets are seating so far out of the case that your COAL is well beyond listed COALs in the manual. Like Twitch2120 mentioned, likely the maximum COAL for these rifles will be limited by the maximum cartridge length the magazines will accommodate. If you have a particular round that fits the magazine and functions well, use the CBTO to maintain consistency. Note that your COAL can change when switching projectiles (due to shape) despite you maintaining the same CBTO measurement, so even with the same CBTO measurement between two different projectiles, one may fit in your mag and the other may not (longer COAL). I say that just as a precaution to check it in your mag prior to loading up a ton and having to pull them…zero fun

 

[RSBrown]

Thanks gentlemen

 

[rotts4u]

Read this a few times. Its a detailed method for measuring your barrel(s)

How To Measure The Distance To The Lands On Your Rifle Barrel

One of the benefits of reloading your own ammo is that you can customize it to your chamber. Factor...

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