Hello I am trying to get a little info for seating depth on my 338 RUM XCR2 factory rifle I am going to be trying 300smks and 285 A-max hornadys and I have no clue how far off the lands I should seat these lets go with the 300smk for depths any info or pointers would be greatly appreciated thanks!
Seating off the lands 338 Rum
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g0rd0
Well-Known Member
size and deprime a case, with the primer OUT and NO powder lube the inside of the neck and seat a bullet in it just enough to hold it in place. Measure it then chamber it. As the bolt closes it will use the rifling as a seat die and seat the bullets ojive on the lands. Slowly eject the dummy and measure the OAL now subtract 30thou from that length. That is a good starting point for that bullet in that rifle and no other.
Now you can either pull and use that bullet or seat it to the less than 30thou and keep it for a die set up point
Now you can either pull and use that bullet or seat it to the less than 30thou and keep it for a die set up point
450hunter
Well-Known Member
I have the same rifle and I load to the magazine length. The bullets are still around .090 off the lands. If you have a stock XCR II the only way to get closer is to single shot it.
450hunter
Well-Known Member
I have always used the method mentioned above.
All the sporting rifles in various calibers I've reloaded ammo for have several hundredths of an inch spread in bullet jump distance to the rifling where accuracy is the same.
On the other hand, if I judged accuracy by the first 3 or 5 rounds of a 20-shot test group for each load, I never got the same results each time. Neither does anybody else.
So, I encourage folks to shoot at least 20 shots per test group. 3- or 5-shot test groups have way less than a 50% chance of representing what all shots of that load will shoot inside of. If your shot start to walk around as the barrel heats up, that's because it's fit poorly to the receiver. Have the patience to let it cool down between shots so you'll see what accuracy is you can count on all the time. Judge accuracy by the largest groups fired. The smallest ones happen when all the variables cancel each other out for the most part.
On the other hand, if I judged accuracy by the first 3 or 5 rounds of a 20-shot test group for each load, I never got the same results each time. Neither does anybody else.
So, I encourage folks to shoot at least 20 shots per test group. 3- or 5-shot test groups have way less than a 50% chance of representing what all shots of that load will shoot inside of. If your shot start to walk around as the barrel heats up, that's because it's fit poorly to the receiver. Have the patience to let it cool down between shots so you'll see what accuracy is you can count on all the time. Judge accuracy by the largest groups fired. The smallest ones happen when all the variables cancel each other out for the most part.
