So I've just started load development on an old .308 I've had for a while. Got some Sierra 155gr TMK's which are the ideal weight for the gun.

First thing I do after setting the proper head space is make up a "loose neck" round to determine the distance to the OGIVE for said rifle, whereby allowing the lands to push back the bullet when the round is chambered. Always used this method with excellent consistency. This time was no exception, I chambered 5 rounds and they were all within .0005" of each other.

Problem is when I set the bullet .015" from the lands the C.O.A.L is 2.960"! Cartridge is too long to fit in the mag. Unsurprisingly really given the max C.O.A.L for .308 is 2.800".

Anyway it's left me thinking 3 things:

1. The start of the rifling in this particular rifle is set unusually far forward?
2. My magazine is on the short side?
3. The profile of the Sierra bullet has a shallow taper and therefor protrudes further from the case before contacting the lands, which leads me on to thinking I might need to try a different bullet?

If I set the C.O.A.L to the recommended length (and so the round fits in the mag) the bullet is going to have a massive .175" jump to the lands, which I'm not happy about at all.

Anyone else come across this problem before?

Cheers
Greg