Bullet Seating Depth

Poconolg · April 2, 2019, 06:02 AM

When shooting a 22-250 at 100 yards how many 1000ths variation on seating depth will start to make a difference in accuracy? Thanks for the help.

sako2 · April 2, 2019, 06:10 AM

It will vary with different bullets. I've see it with .005 in seating depth. With my 22-250.

cw308 · April 2, 2019, 09:01 AM

I would agree with Sako2 ,..005 is pretty small when looking at it but is enough to see a change . That said your case sizing also has a important part to the round . That's why I switched from neck to full sizing for benchrest shooting . I want to start out with my cases as close to exact as possible . If there's different wiggle room in your cases jumping or jamming is out the window . Neck sizing the OD may be good but the lengths aren't the same .

zplinker · April 2, 2019, 09:52 AM

Pick a seating depth of .020" off the lands, and make up loads longer and shorter, in .010" steps. Assuming your rifle is capable of delivering needed accuracy, you should see the groups go through a valley when you hit a 'sweet' spot. And even .010" steps may be too much, but generally has worked for me. If this doesn't show results, there is a good chance that other factors are influencing your groups, like poor bedding, on and on. Some barrels don't like some bullets too, so that is another thing to look at. As CW308 mentions, case prep is critical. You need to eliminate as many variables as possible, so when you change one thing, you can be fairly confidant that changes you see can be attributed to that change.

RC20 · April 2, 2019, 12:13 PM

I do .010 steps as the bullet variation even on Ogive is .005.

Sometimes I find one that is really more like .008-.010

Reality if you you do .010 your are only .005 off the mean.

PA-Joe · April 3, 2019, 06:50 PM

Take a look at your bullets and measure them from base to tip. Lead points may be off 0.01.

jmr40 · April 3, 2019, 07:26 PM

I always start with the bullets as long as possible that will still fit in the magazine and chamber in the rifle. That way instead of trying to experiment with longer and shorter OAL you only have one direction to go. You can't make them any longer. And most of the time that is where I find best accuracy.

April 2, 2019, 06:02 AM	#1
Poconolg Senior Member Join Date: April 5, 2015 Posts: 171	Bullet Seating Depth When shooting a 22-250 at 100 yards how many 1000ths variation on seating depth will start to make a difference in accuracy? Thanks for the help.

April 2, 2019, 12:13 PM	#5
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,334	I do .010 steps as the bullet variation even on Ogive is .005. Sometimes I find one that is really more like .008-.010 Reality if you you do .010 your are only .005 off the mean. __________________ Science and Facts are True whether you believe it or not

April 3, 2019, 07:26 PM	#7
jmr40 Senior Member Join Date: June 15, 2008 Location: Georgia Posts: 10,975	I always start with the bullets as long as possible that will still fit in the magazine and chamber in the rifle. That way instead of trying to experiment with longer and shorter OAL you only have one direction to go. You can't make them any longer. And most of the time that is where I find best accuracy. __________________ "If you're still doing things the same way you were doing them 10 years ago, you're doing it wrong" Winston Churchill

April 2, 2019, 06:10 AM	#2
sako2 Senior Member Join Date: April 12, 2009 Posts: 766	It will vary with different bullets. I've see it with .005 in seating depth. With my 22-250.

April 2, 2019, 09:01 AM	#3
cw308 Senior Member Join Date: September 2, 2010 Location: Plainview , Long Island NY Posts: 3,863	I would agree with Sako2 ,..005 is pretty small when looking at it but is enough to see a change . That said your case sizing also has a important part to the round . That's why I switched from neck to full sizing for benchrest shooting . I want to start out with my cases as close to exact as possible . If there's different wiggle room in your cases jumping or jamming is out the window . Neck sizing the OD may be good but the lengths aren't the same .

April 2, 2019, 09:52 AM	#4
zplinker Senior Member Join Date: February 21, 2011 Location: way out here Posts: 262	Pick a seating depth of .020" off the lands, and make up loads longer and shorter, in .010" steps. Assuming your rifle is capable of delivering needed accuracy, you should see the groups go through a valley when you hit a 'sweet' spot. And even .010" steps may be too much, but generally has worked for me. If this doesn't show results, there is a good chance that other factors are influencing your groups, like poor bedding, on and on. Some barrels don't like some bullets too, so that is another thing to look at. As CW308 mentions, case prep is critical. You need to eliminate as many variables as possible, so when you change one thing, you can be fairly confidant that changes you see can be attributed to that change.

April 3, 2019, 06:50 PM	#6
PA-Joe Senior Member Join Date: June 9, 2010 Location: NEPA Posts: 909	Take a look at your bullets and measure them from base to tip. Lead points may be off 0.01.