Confused about loading 6BR COAL

[Pareto]

I started reloading 6mm BR Norma for the first time and when I just started to try to load at SAAMI spec with new Lapua 6br brass and 68gr Euber bullets I found it basically impossible to load to 2.441 COAL without the bullet falling out. The most I could go was around 2.375 and mostly 2.360. At longer lengths, there was almost no or very minimal seating depth. Base to ogive was max around 1.91.

Am I missing something?

At this point, I'm not even interested in optimizing the load. Just getting something decent to start where the bullet won't fall out and I don't blow up the gun/myself/etc.

 

[Jager]

Different bullet weights/designs will have different lengths. With a shorter bullet, like your 68 Euber, your COAL will be shorter than if you had used a longer bullet.

Disregard that 2.441 and simply load the bullet to a COAL that gives you adequate strength, desired neck tension, and optimum accuracy.

 

[Richard Jones]

IIRC, the 6BR Norma CIP spec was designed around longer 100-ish gr. bullets, not 68's. That said, it's all going to depend on the freebore in YOUR barrel. Do you know your 'touch' number? Are the 68's in the lands, off the lands, etc.?

 

[6BRA]

Seat them with .243 inside the neck, start low on charge weight and move up. Disregard COAL. You may be able adjust COAL a little but this is the general rule. The bullet diameter inside the case neck.

 

[Webster]

I started reloading 6mm BR Norma for the first time and when I just started to try to load at SAAMI spec with new Lapua 6br brass and 68gr Euber bullets I found it basically impossible to load to 2.441 COAL without the bullet falling out. The most I could go was around 2.375 and mostly 2.360. At longer lengths, there was almost no or very minimal seating depth. Base to ogive was max around 1.91.

Am I missing something?

At this point, I'm not even interested in optimizing the load. Just getting something decent to start where the bullet won't fall out and I don't blow up the gun/myself/etc.

I only have loaded rounds at hand now with 58 gr Hornady VMax bullets. I have 0.030" free bore. At 0.010" jump my OAL is 2.129". That SAMMI spec is .312" longer than I put them. Forget the SAAMI spec. you need to determine touch so you have a good reference number. My Berger manual also says 2.441 COAL which doesn't make sense to me. Lost a lot of my touch recorded data when my computer crashed. Never seated any bullet over 2.200" COAL. Just took some quick measurements with a caliper. At 2.441" COAL a 58 gr bullet would be outside the neck of the case??? Don't see how you could chamber a 2.441" COAL bullet???

 

[Bill Norris]

The 2.441 is referencing a longer bullet like maybe 105 gr. Those numbers are reference and only come into play with the cartridge fitting into the mag. Each and every loaded different bullet will require it's own CBTO in relation to bullet seating depth.

 

[Pareto]

IIRC, the 6BR Norma CIP spec was designed around longer 100-ish gr. bullets, not 68's. That said, it's all going to depend on the freebore in YOUR barrel. Do you know your 'touch' number? Are the 68's in the lands, off the lands, etc.?

I measured to the lands using a Euber bullet and I got a COAL of 2.196 and base to Ogive of 1.728. Seeing the SAAMI spec, I was worried I'd done something wrong in measuring and might have too compressed a load at that COAL. Should I just go to that measure or do slightly more like 2.2 or 1.73? I just don't want my loads to cause issues. I'm using Varget and have an initial ladder going only from 31 grains to 32.9 in five steps to be safe.

 

[Webster]

I measured to the lands using a Euber bullet and I got a COAL of 2.196 and base to Ogive of 1.728. Seeing the SAAMI spec, I was worried I'd done something wrong in measuring and might have too compressed a load at that COAL. Should I just go to that measure or do slightly more like 2.2 or 1.73? I just don't want my loads to cause issues. I'm using Varget and have an initial ladder going only from 31 grains to 32.9 in five steps to be safe.

If touch was 2.196 I would start at 2.185" COAL. I don't like to jam so I know I can extract a loaded round with out dumping powder in the action or having the bullet pull out longer before it's released. I don't shoot competition. A life long varmint hunter. My rifles shoot under 0.400" groups.

 

[Jeff Porter]

COAL is really only valid for a specific bullet listed in a loading manual. The shorter stubby bullet you plan to use will have a shorter OAL but beware you can jam them pretty easily because the ogive is a heck of a lot closer to the tip of the bullet.

You will also find variation in bullet length is much greater from ogive to tip than base to ogive. Controlling your seating depth to the tip of the bullet may actually give 0.010" or more variation in hollow point match bullets. Seating to your ogive reference will produce rounds that have the same amount of bullet in the neck and the same amount of jump to the rifling, even with COALs that vary.

 

[divingin]

I started reloading 6mm BR Norma for the first time and when I just started to try to load at SAAMI spec

Is there a SAAMI spec for 6BR Norma? It was standardized through CIP. I've never seen SAAMI specs for a 6BR Norma.

That said, the SAAMI (and CIP) cartridge and chamber drawings are for use by manufacturers to set an "industry standard". What's out in the world may or may not fall within those parameters.