Pierced a primer on my 280 AI need info?

E

elmerdeer

Regular
Rating - 100%
7   0   0
I was doing load development with my new 280AI and I pierced a primer. It was with 64grs of RL-22 and 140gr accubonds with my bullets seated .015"off the lands COL was 3.345" and my velocity was for a 10 shot string was between 3197 to 3267 as the high. the primer pierced on the 3rd shot which had a velocity of 3205, the rest of the rounds did not pierce any of the primers but they were a little fletter.I was using brand new Nosler brass and CCI BR 210 primers. In nosler's book the charge is a Max charge and the velocity is the same as I was getting, so I am wondering if it was a faulty primer or am I in DANGEROUS territory? My barrel is a Krieger 1-9.5 twist in Win Featherweight countour.
Thanks
Elmer
 
If you pierced a CCI BR primer something ain't right. Is the COAL the same as the one in the Nosler book? Seating closer to the land than the load in the book can raise pressures signifigantly. I'd say that may be the issue or something happend with that one round and you'll never figure it out.
 
Nosler brass has less volume than their competitors, and this is likely part of your problem. Next time you work up a load, try using the chronograph to give you an indication of maximum pressure. Starting at the suggested starting load increase 1 gr per load. When the maximum load is reached the velocity will plateau, that is if your subsequent loads increased 40 fps or so, when your load reads only 20 fps or slightly less, you have reached you maximum load. From that point I consider the previous load to be my maximum working load as the extra 20 fps does not justify the additional pressure. If I want to tweak the load for maximum accuracy, I work backwards from the plateaued load, until I hit the sweet spot.

There are several methods of determining maximum pressure when working up a load, but short of a pressure trace, most rely on observations such as leaking primers, flattened or punctured primers, extractor marks on the case heads, case head expansion, or a sticky bolt. None of these indicators is a very precise method of determining a maximum load and they require a fair bit of experience to read accurately. The chronograph method I believe is safer and much more precise.
 
give 'er he11...everyone knows in order to beat factory 7 Rem Mag velocities with a 280AI you have to pump up the pressure....and it looks like you're there.....that's the true concept of an Ackley chamber...:D

now..where are those Nomex coveralls.....?:D
 
Last edited:
elmerdeer said:
the primer pierced on the 3rd shot which had a velocity of 3205, the rest of the rounds did not pierce any of the primers but they were a little fletter.
Click to expand...

Stop !Your Rifle is trying to tell you something.....if your charge has enough pressure to pierce a primer its usually time to start working down, The flat primers in the rest of your string confirm it.
 
You must log in or register to reply here.
Back
Top Bottom