So I'm early in my load development for my new to me CZ in .416 Rigby. First go at the range was with 400gr A-Frames. I seated those to crimp in cannelure which gave a COAL of 3.63", well short of SAMMI length of 3.75". One of the H4831 loads gave pretty good accuracy.

This week I loaded up a dozen 400gr North Fork softs. I seated these to give a COAL of 3.75". At the range today when I went to load these the rounds would not chamber properly. The bolt seemingly went all the way forward but would not lower. I confirmed length of the bullets when I got home. Measured from the flat front of the bullet to the base of the brass.

What am I doing wrong? I've never had this happen before.

Just how your chamber is. My CZ 550 won't take 400 grain RHINO monometal solids unless seated to last ring (3.470") but easily takes 400 grain RHINO softs (3.620"). The ogive is different between the two -- seat deeper. BTW, to get the same velocity and POI I had to go with H4831SC at 100 grains for softs and 90 grains IMR 4831 for solids, wanting to crimp. Softs crimped at cannelure and the extra long bearing surfaces of the solid have to be good enough for me there.

I find it a very simple process on big bores to check the overall cartridge length with a particular bullet which gives you the OAL to load your cartridge to prevent the bullet jamming into the lands. It has been posted before by others but IMO it is one of the simplest and accurate methods not requiring any other tools other than a flat ended cleaning rod and of course calipers.

Close the bolt on an empty chamber and poke a flat ended cleaning rod down from the muzzle until it touches the bolt face, mark the rod with fine tip biro pen at the muzzle. Open the action and push a bullet into the chamber using your finger or a case to hold it stopped against the lands, don't force it into the lands. Push the cleaning rod from the muzzle until it contacts the bullet and again mark it at the muzzle. You can use the rod and your finger to push the bullet back and forward until it just firmly contacts the lands to get a good measurement. Measure the distance between the two marks on your cleaning rod and that is then the definitive OAL of your cartridge with that bullet snuggly touching the lands. Shorten this measurement by at least .020" or a bit more for a DG gun, especially using some bullets which require a jump to the lands, and that is then your maximum overall cartridge length with that bullet.

This method takes care of the differant ogives and bullet shapes.

Thanks for the replies gents. I guess I knew the answer was to seat the bullet deeper, but couldn't wrap my head around it. Just figured SAAMI length was the max for all bullets.....guess I'm showing lack of experience. Sure wish I hadn't crimped these. I'm thinking it'd be a bad idea to seat them deeper without pulling the bullets and resizing the brass to remove the crimp.

eagle27, might give your method a try. I'm got my own tricks I've used when trying to seat for longer than SAAMI length. I like your method however.