First Loads in Long Time - Help Me Read These Groups

[TX_Diver]

Shot my first reloads for the .223 over the last few weeks.
Each set was shot in 1 setting (i.e. FC brass was shot 3/13 and LC brass shot 4/17). 3 shot groups with a few min between each group.

I originally was going to use FC brass but then I got some LC on a trade and switched.

I loaded 6 of each and was intending to do this and also shoot 3 of each across a chrono but on firing up the chrono it's broken so that's out. I am hoping to determine a charge weight and then proceed with a seating depth test.

Based on the below I'd be curious as to what y'all think. I don't have an app that does the fancy measuring unfortunately. The FC groups are for reference but I'd like to proceed with the LC brass since I have more of it.

Tikka T3x Lite in .223 w/ 1:8 Twist barrel
SWFA 6x scope
.223 Remington
77gr SMK
Viht N140
CCI No 400 SRP
1.953 CBTO
~2.341 COAL

Loaded FC from 19.5gr to 21.9 gr in .2gr Increments
Loaded LC from 19.3 gr to 21.9 gr in .2gr increments
Sierra lists 19.5 as the starting load and 22.3 as max.

Everything shot prone w/ a bipod and rear bag.

I'm planning to use the LC brass so these pics with FC are just included for reference. These were loaded and shot before I had the LC brass. At 21.7gr I got 3 slightly flat primers and stopped.

Boxes are 1" square

FC Brass 19.5 to 20.5

FC Brass 20.7 to 21.7

LC brass is mostly LC19 but within that there are a variety of headstamps still. I did not get any pressure signs so I can go load up 22.1 and 22.3 if needed.
LC Brass 19.5-20.3 - Note I dialed .2 down from 19.3 to 19.5 and .1 right from 19.5-19.7

LC 20.5-21.5

LC 19.3, 21.7, and 21.9

 

[jakelly]

I’d be looking from 20.0-20.7 with 5 shot groups and using different seating depths to look for as much utility as I could.

 

[Newbie2020]

Seating depth and measuring powder to the kernel probably affect accuracy (precision) more than any given powder charge velocity “node”. As @jakelly said, pick a middle charge and run a seating depth test.

@Dthomas3523

 

[TX_Diver]

I’d be looking from 20.0-20.7 with 5 shot groups and using different seating depths to look for as much utility as I could.

With no chrono I can go shoot another 3 shot group of each.

I was leaning towards just picking 20.3 and playing with the seating depth from there but figured I'd check in and get some other opinions.

I have a chargemaster lite and essentially mixed brass so I can probably only hope for so much but I'm kinda teaching myself at the same time and learning, so I'm trying to at least make sure I understand what I'm doing and not going to far astray.

 

[jakelly]

I wouldn’t do that. The thing with three shot groups is one shot can throw you off. If I were you, I’d shoot five shot groups with the seating depths .010”-0.20” apart. Whichever load showed the most resistivity to seating depth changes would become my load. I would do further seating depth tests and find the widest node I could.

 

[jakelly]

Different HS of LC won’t matter. You’re looking for serviceable not extreme accuracy.

 

[TX_Diver]

One more question... do the charge weights seem low?

Vihtavuori lists 21gr as the starting charge weight and 24.7 as the max...

 

[TX_Diver]

Took me awhile to get back to this...

Debating whether I need to go past 22.9gr N140 w/ the LC brass or just pick 22.5, 22.6, or 22.7 and roll on to my seating depth test. Not sure what velocity I'm really targeting w/ a 22" barrel. Open to suggestions!

I got the chrono replaced and loaded up 22.1 to 22.9 N140 w/ the LC.

Data for 3 shot groups w/ LC brass is:
20.5gr - 2339 fps - SD 19 ES 39
21.5gr - 2433 fps - SD 9 ES 17
21.7gr - 2463 fps - SD 12 ES 17
21.9gr - 2492 fps - SD 19 ES 36
22.1gr - 2515 fps - SD 38 ES 68
22.3gr - 2521 fps - SD 6 E2 12
22.5gr - 2530 fps - SD 8 ES 20 (5 shot string)
22.7gr - 2562 fps - SD 8 ES 21 (5 shot string)
22.9gr - 2588 fps - SD 37 ES 81 (4 shot string)

I went back to the FC rounds I had loaded up and shot a few various charge weights to get data points since I had the rounds done.
20.5gr 2354 fps - SD 5 ES 10
21.5gr - 2445 fps - SD 21 ES 42
21.7gr - 2447 fps - SD 13 ES 27 (this is where I got flat primers last time). Today they were ever so slightly different than the 21.5gr load but not flat like last time. I still stopped though as I'm planning to shoot LC brass. It was about 20 degrees warmer today than last time I shot.

 

[pabrousseau]

Nothing wrong with flat primers?

 

[pabrousseau]

I meant for that question mark to be a period.

 

[sinister]

N140 is an OK powder.

With a .223 Remington, unless you're shooting benchrest you're at the lower end of density and velocity. Sierra is notorious for low loads. You should look at other loading manuals / charge books.

400 primers are for low-pressure rifle loads (like benchrest and .30-caliber M1 Carbine) and will show pressure signs earlier. Try 450s.

Try 24.0 grains of N140. It's in the "Safe" range per Lyman's 49th edition and should net you around 2650 fps from a 22-inch barrel at 2.250 overall length for an M16 magazine. Just curious, how did you settle on 2.341" overall?

 

[99106]

Assuming you were holding same point of aim for every group, I'd be inclined to start at the 21.5 since the whip seems to be somewhat consistent, and then try to adjust seating depth for tighter groups. However, the Sierra 5th does not show bolt gun data for the 77gr with N140. Interpolating between the 69 and 80gr bolt gun data it seems 21 would be on the lower end of the charts.

As for the flat primers, pockets may be too loose on the Fed brass? Make sure brass is trimmed within specs and not squeezing bullet because it's too long creating more pressure. Clean your chamber with alcohol, maybe you inadvertently got some oil in there.

 

[Mudflap621]

My t3 varmint likes the 77smk 5 thousandths off but man I wish I could load them out this far lol. I’m at 1.835 cbto.

As already stated I also found seating depth test to really improve my groups.

I don’t really care about speed as much as group so if it was me I’d run a seating depth at 20.2 but 21.5 would peak my interest as well.