Seating depth results

[pelikan800]

Well, I’ve been working with my new 6mm BR Norma rifle and wanted to get some thoughts on my seating depth test. A little background. I took a Rem 700 in 6.5CM and removed the barrel and installed a 26” Criterion barrel (1:8 twist) using an NSS barrel nut system. It’s in a KRG Bravo stock with a Trigger Tech trigger.

I first put 100 rounds through it using some Sierra 95gr MK’s I bought locally to break it in. I’m using Lapua brass. I then proceeded to do a powder test with Varget and Berger 105BT bullets and got 28.8gr. of Varget being the best with an ave. velocity of 2,730 and an ES = 6 and SD = 2 which is the best I've ever gotten from a rifle. Last week I did a seating depth test and got the following results.

None of them made great groups. I’m guessing that might be due to myself needing to become a better shooter! With that said, I am looking at group 3 at 1.714”being a possibility as I may have been the reason for the flyer on the left of the group. The other group I though held promise was number 5 at 1.704” seating depth as that is beginning to look like a group. What say you more experienced folks? Is my shooting ability hindering being able to do a seating depth test? Are groups 3 and 5 worth loading up some more 5 round test ammo and trying some more? Thanks!

 

[6bra1k]

what did the powder test groups look like...
statisics do not mean crappola if the groups suck

 

[Clancy]

Start at 1.714 and go shorter by .002 increments down to 1.694 if that’s still safe. It’s pretty clear it wants them shorter. It could be that 1.714 was the winner. That left shot sure looks like wind or rear bag handling. I’m just saying at look around those 2 shortest ones thoroughly.

 

[Bronsin]

Just my observations, using 5 shot groups for an initial seating depth test is unnecessary. 5 shots will work for verification though. You fired 5, 5 shots groups. What is the touching length? If you fire 8, 3 shot groups, from .003 off to .027 off, you would have found something decent. The length jumps you are using right now are too big. The node will only be .006 wide, and you're making .010 moves.

In the end, it would have used the same number of shots and covered more seating depths in finer increments.

 

[pelikan800]

Bronsin, I started 0.020" off the lands. The lands are at 1.744", so I began at 1.724".

6Bra1K, I didn't shoot groups for the powder test. I used the Satterlee method by shooting a dozen rounds, .2 gr. apart up to the max per the Berger manual and chrono'ing the results looking for flat spots and found two. I decided to use the higher powder flat spot.

 

[Clancy]

Bronsin, I started 0.020" off the lands. The lands are at 1.744", so I began at 1.724".

6Bra1K, I didn't shoot groups for the powder test. I used the Satterlee method by shooting a dozen rounds, .2 gr. apart up to the max per the Berger manual and chrono'ing the results looking for flat spots and found two. I decided to use the higher powder flat spot.

That is probably why the groups aren’t great. There’s no substitute for hard work.

 

[Clancy]

Whether you do your seating depth first or redo powder first, so far you’ve learned very little about the rifle.

I always do seating depth first, very throughly, but to each his own on that.

 

[pelikan800]

So you're saying the Satterlee method is useless, and I should use the OCW method for powder charge?

 

[JFrank]

28.8 gr of Varget at 2730 fps is about a hundred fps slow for a straight six.

 

[Clancy]

So you're saying the Satterlee method is useless, and I should use the OCW method for powder charge?

What I’m saying is that with no disrespect to Scott or anyone else for that matter, if your powder work doesn’t involve shooting a bunch of bullets at paper and analyzing the size and orientation of groups then it’s worthless.

 

[6bra1k]

So you're saying the Satterlee method is useless, and I should use the OCW method for powder charge?

very close to the truth except ocw goes in the mix also.
the truth is the original ladder works for most rifles tho short range br were alot is already known. just shooting groups works well.
my opinion is the current "inventor" never knew how to do a ladder correctly.
do you know a velocity window(node)that has known accuracy in your cartridge/bullet?
start at TOUCH not jam nor off. this is a pressure point....in or out will change pressure .
run a simple 20 shot .2 step ladder measuring velocity and plotting each shot on a bench target.
the target may show possible nodes, plotting the shots in a velocity/powder weight graph may show possible nodes.
does your known velocity node show up ?
load 3 of each that look possible and shoot them.
shoot 5 shot groups of those that were proven in the 3 shot target.
now shoot the best in steps of 0.005 off, 0-25 and see what happens.
find a better in there , try either side of the test by .002.
now you can play with neck tension if you choose.
does this work ?
i just won a 600 yd br match and had not finished the development.
go look at the thread 6mm dasher 105 barts rl 15.5 i4895

 

[FeMan]

There are a lot of things that matter, but IME the single most important element to good accuracy is seating depth, and little changes can matter a lot. Your seating depth looks like 0.010" increments or random from the photos. Pick a starting point and move in or out in 0.003" increments. The seating depth and accuracy plot like a sine waive and accuracy will periodically repeat. There are multiple nodes for seating depth but one will be optimal.

I typically start at 0.010" jump and shoot 4-shot groups to 0.050" and sometimes out to as far as 0.080". I then take the best one(s) and retest them and the depths on either side. If it repeats, then I take the best one and play with powder charge on the selected seating depth.

Thats the basics. The next step is I take my stuff to 1k and fine tune after that testing seating depth at 0.001" as well as powder charges and if I think I can better, I play with neck tension.

FWIW, I do chrono my loads but I do not load based on the results. I have loads that have ES over 45 that I have won matches with. The chrono makes me want to puke sometimes but the target is all that matters. I wonder how many awesome loads have been aborted due to chronographs?

 

[X-Caveman]

28.8 gr of Varget at 2730 fps is about a hundred fps slow for a straight six.

This^^^. If it were me, I would try more powder - usual disclaimers apply. I like doing it in the lands as far as I'm willing to go. Then, once settled on a powder charge, you only have one way to search on the seating depth. It's easy to bring an arbor press and Wilson die with you to the range. If first two don't touch (and there's no explanation), stop & try a few thou shorter.

Also - what scope are you running? Everything tight?

 

[rr1220]

my last 2 barrels were bartliens and shot the 105bts well ( .3moa consistantly) @.015 jump
current criterion barrel would not shoot them jumped , currently .015 in from touch
some guy named Bart suggested load @ .010 in and do a charge test this way there is only 1 direction to go

 

[JFrank]

This^^^. If it were me, I would try more powder - usual disclaimers apply. I like doing it in the lands as far as I'm willing to go. Then, once settled on a powder charge, you only have one way to search on the seating depth. It's easy to bring an arbor press and Wilson die with you to the range. If first two don't touch (and there's no explanation), stop & try a few thou shorter.

Also - what scope are you running? Everything tight?

Me too, I start mine at .025 in on my Ackley however the straight six with a Criterion likes a couple different bullets, all of them are closer to 30. Gr of Varget

 

[JEFFPPC]

I see some good thoughts in the above posts. But, if your not using flags and I see no mention of them, how do you know you were shooting in the same condition for all shots in a group? I don't need an answer, just consider the question and use it to your benefit. There appears to be excess horizontal as a big problem. A house is only as good as it's foundation.

 

[PopCharlie]

I see some good thoughts in the above posts. But, if your not using flags and I see no mention of them, how do you know you were shooting in the same condition for all shots in a group? I don't need an answer, just consider the question and use it to your benefit. There appears to be excess horizontal as a big problem. A house is only as good as it's foundation.

JeffPPC,
This was something my stubborn arse had to learn(it took 6 years and 3 rifles). 3 things have to be good, besides good ammo. Bench manners, barrel cleaning and wind reading skills. Otherwise, load development is a mystery.
PopCharlie

 

[JFrank]

I do take at least one flag every time I go to the range however I think it’s a mistake to correct for wind values during testing.

 

[CNC-Dude]

FWIW, I do chrono my loads but I do not load based on the results. I have loads that have ES over 45 that I have won matches with. The chrono makes me want to puke sometimes but the target is all that matters. I wonder how many awesome loads have been aborted due to chronographs?

Wise words! Too many shooters get hung up on ES and SD numbers when the target should dictate what the gun likes....

 

[Bill Norris]

Wise words! Too many shooters get hung up on ES and SD numbers when the target should dictate what the gun likes....

Absolutely truth. It is strange to see a 1/4 MOA 5 shot group have over 100 fps extreme spread and a 3/4 MOA 5 shot group have 5 fps extreme spread but I've seen it happen. The main reason I don't place much confidence in those chrono numbers. My target always wins that battle.