Finding "sweet spot" with bullet seating adjustment

[ShtrRdy]

For those of you who have experienced finding a good load by adjusting seating depth what size steps did you take?

My bench rest friends take 0.003" to 0.005" steps. And Berger says you can take 0.040" steps.

 

[DUSTY NOGGIN]

(5) 5 round batches , 015 to 020 off + 010 +010 +010 +010
(4 shots in this pic )

thatll usually give you a visual of what it wants , you can always take it further with the 003 & 005 once you narrow it down

there was scope adjustments in this array .. first group once i seen it was gonn be too big i centered it for last shot ..

then after i seen the 3rd group i adjusted scope down again to get bull

found .035 off was my best seating with this charge .. have not verified yet but will do a couple of 5 shot groups around that .. .030 , 035 & .040 ... if it stays put . i will have found my load

--all these had exact powder charges .. to the gnats *** ..
-- the target squares in the picture are .875" .. i skew my target to match my scope retical
-- i called that flyer in the 3rd group , that doesnt ,mean it was gonna be in the group .. but once i verify that group ill know ..
-- also need to verify my speeds again to see if SD stayed

 

[Deputy819]

I like to move in .010 increments until I see what I'm looking for and then "wiggle" a little (.002/.003) either way to see if it tightens any more.

 

[Rick Richard]

I like to do .010 then .030 and have never needed to go beyond this.

 

[Mikecr]

Same as DUSTY

 

[Mike 338]

I go with the Berger method. I have a rifle that wouldn't group till it had a .225" jump. Gonn'a have a rough time finding that out in .005" increments.

 

[MudRunner2005]

I seat mine at a static depth pre-chosen before loading, and then adjust powder charge from there to find the most accurate load. Typically seat mine .010"-.015" off the lands.

 

[YZ-80]

I always start out at .020" off the lands and rarely have to adjust it. I might be .015 off the lands on one of my .243s but I've rarely if ever made .002 to .003 adjustments in seating depth and don't see the need to as I get .5 MOA performance out of every rifle I reload for. Then again, I'm maxing out at 400 yards where I hunt, so these types of adjustments aren't necessary for me. I do think closer (but not too close) is better. I like to strike a compromise between maximizing accuracy and being kind to my equipment. That said, I have a ton of respect for you guys that push the envelope, seat close, reap the long range benefits and swap your own barrels out. You are my hero's!

 

[FURMAN]

Out of 50 plus rifles I have done load development for every single one of them has had a huge group size change from seating depth changes. I have had the exact same reamer chamber barrels that preferred different seating depths. I have never had a rifle prefer more than .060 off the lands and most are under .040 off. I do changes in .010 increments until I find the best and then do .005 on either side.

 

[ShtrRdy]

Thanks for the info! I'll try changing seating depth in 0.010" steps and then go from there.

 

[jasonco]

.010 increments up and down from the original start position, for me.

 

[MNbogboy]

I go with the Berger method. I have a rifle that wouldn't group till it had a .225" jump. Gonn'a have a rough time finding that out in .005" increments.

I believe that the course Berger increments will let you pass right by a seating "node". Usually there is more than one "node" (as also with powder).
.010 increments will most times get you close enough to detect these and tune with .003-.005 both ways from there. An .040 increment would pass by totally with no indication of better grouping.
That's my feelings & $.02,
Randy

 

[MNbogboy]

Also using a target similar to Dusty's (without scope adjustment If possible) will show similarities in POI when seating is getting close. When groups tighten and remain same POI within .005 either way you have found one of the seating nodes. Usually there is more than one node. I start .010 off the lands where magazine length allows. Start at max mag length if you are unable to reach the lands.

 

[Mike 338]

I believe that the course Berger increments will let you pass right by a seating "node". Usually there is more than one "node" (as also with powder).
.010 increments will most times get you close enough to detect these and tune with .003-.005 both ways from there. An .040 increment would pass by totally with no indication of better grouping.
That's my feelings & $.02,
Randy

Yup, you could be quite right. The Berger theory is... find the neighborhood and fine tune later if you must. In most cases though, a rough seating depth test often yields a group that is noticeably better than the rest. This in theory, puts you in the "sweet-spot neighborhood" and you can fine tune later if you must. Usually it isn't necessary because the optimal band is so wide. It's all theory till you test it though.