Vartarg Seating Depth Test Question

[toasty]

Just want to get input on these seating depth results. This is a CZ 527 with a pacnor vartarg with H4198 shooting 32gr SBK. Charge is 18.3gr with velocity at 3725 fps. Top left is right at the lands and then testing moving .003" out from there on the other three groups. At 100 yards, each group measures between .350 and .400". Everything with this bullet and powder shoots about the same. Seating depth does not seem to help or hurt groups which is not what I usually see. My question is there sure seems to be a bimodal component here as every group has 2 shots touching and 1 off which is making me think I do not have a good node for powder charge. These were not shot round robin, all 3 in a row. I know everyone says it is not me, it is the gun, but I shot 2 other rifles with both shooting several groups inside of .200 yesterday evening. I want to test a .003 and .006 jam to see how they look, but I am running out of case neck for this bullet and would prefer to move it the other way. I know 5 shot groups would probably be more information and I need to keep testing moving away from the lands to find a better node, but my H4198 is is short supply and trying conserve. Opinions on what might be going on here?

 

[L.Sherm]

I dont like what I see in any of them, you have 1 outlier in all of them. I bet if you stepped back to 200 the outlier would be more pronounced. Different powder or primer may help

 

[BoydAllen]

What is the action bedding situation? What is the rest/bag setup? Where is the front bag on the forearm? What sort of hold do you have on the rifle?

 

[toasty]

What is the action bedding situation? What is the rest/bag setup? Where is the front bag on the forearm? What sort of hold do you have on the rifle?

Pillar bedded. Shot with front bag that cradles rifle up to the trigger. Only hold is the one hand on the rifle and trigger, other hand is on the rear bag adjusting elevation.

 

[Gabe22BR]

From what I see=
Your powder charge is off-…
You got vertical-

That one flyer= seating depth…

Tip~ shoot a sighter off paper (1st shot) before doing test…it’ll warm & foul the barrel

 

[L.Sherm]

I agree with Gabe also, take your best seating depth and test 18.0, 18.1 and 18.2.
If that doesn't work time to test different powder and primer

 

[toasty]

Thanks guys, always appreciate feedback. I do think I am on the high end and pushing a little hard at 3725. These were loaded with Fed 205s and they show some mild cratering. Would you guys switch to 205M, BR4s, 450s for the retest or stick with the 205s? A few days ago, I tested 18.0 and 18.2 powder charges and got more horizontal stringing on both loads. My 18.2 and 18.4 groups had the same POI which is why I chose the 18.3 and my 18.4 test has the same 2 group characteristic. Probably should have seen this coming.

 

[Gabe22BR]

I’m a 205M & REM 7-1/2 primer guy..

Those waterline-“horizontal stringing” is what you want… it’ll either be wind, you, or equipment..

 

[SD guy]

Toasty, I'll be following along. Do you have RL7 or N120 by chance? Sounds like 4198 very difficult to imposable to source in the future. May wish to do load work up with a more redably available powder if you can, at least for the time being.

I'll be testing a 24" Varmint contour Pacnor, 11 twist before long.

What barrel length are you working with?

 

[L.Sherm]

I'm a 7.5 guy in all my 20VT's, 20 Prac and 20PPCAI, the only thing I use 450's in is my 20BRA

 

[TheCZKid]

I use either 400's or 7.5 as well, and RL7 and N120 are both about equal in accuracy for me. N120 is currently available, and for an 8 pounder it's UNDER $300, or about $90 less than Hodgdon 8 pounder. Good time to buy it, very accurate for 20VT.