Forgotten .223 goodness

[hounddawg]

A few weeks back while scrounging around in my bullet drawer I ran across 3 boxes of 77SMK's that I had bought several years ago for my AR's. They shot great from my 1-8 twist Kreiger barreled AR but I had never tried them in my bolt .223. I loaded up 25 of them in Lapua cases with 21.5 to 23.5 of varget and then they sat on the shelf for several weeks until they caught my attention yesterday. To put it mildly I was shocked by their consistency and they will be my new match bullet of choice at 300 I think. Velocity averaged from 2604 FPS for 21.5 gn's up to 2802 for 23.5 gn's. Notice how the groups rise slightly with the velocity and also shift slightly from left to right with the barrel harmonics. Wind was blowing 5 mph from right to left intermittently and I tried to time my shots during the lulls

edit seating depth was 2.260 COAL

 

[Unclenick]

They do shoot well. I have several thousand left from a big purchase I made with some friends awhile back. For 200 yards offhand and sitting rapid, the little 53-grain flat base SMK's seem to work well enough, but at 300 the wind starts to tell, and the little guys are then out of their league.

See if you can find a sweet spot where the left-to-right shifting stops. If not, it may be a recoil moment (whole gun moving slightly) rather than a barrel bend or muzzle deflection phenomenon. In that case, watch for it to change with your shooting position. If it does, all I know to do is note it in your log book and put it on your checklist for sight adjustments for each match phase along with your come-ups.

For general stability information, what is the barrel twist on your bolt gun and is it the claimed twist or twist you've confirmed by measuring? What were the range weather conditions; temperature in particular?

 

[hounddawg]

Range conditions were a sunny 75 degrees, mild intermittent wind from 3 oclock with minor mirage. I had 4 wind flags (driveway poles with marker tape) set at 25, 50, 75 and 100 yards. Gun is a Stevens 200 action from a pawn shop special, the gray plastic stock was cracked and I picked it up for $125 and sold the original .243 pencil barrel for $75. I replaced the broken stock with a Choate and originally had a Criterion .204 Ruger barrel on it. After 3K .204's it dropped down to .75 groups and I replaced it with a .223 barrel from Criterion. Scope is a Clear Ridge and the trigger is a Rifle Basix. The entire rifle including optics cost just a tad over $1000 to build 10 years ago. The current barrel has about 2K rounds down the tube

Looking at the 21.5 group 4 of the 5 were practically in the same hole. At 22.0 and 22.5 the groups went vertical and at 23.0 went circuler then at 23.5 back to horizontal. Tony Boyer has a good section in his book on Rifle Accuracy on tuning loads and how a slight change in powder or seating depth can tune group orientations. He prefers his groups to be a slight bit vertical, he believes that helps with wind caused stringing. With this bullet I will be using the 21.5 load and varying the seating depth up and down in .003 increments to pull the group together. I am pretty confident I can get it to shoot the .2's and .3's consistently.

 

[Unclenick]

Yes, Boyer's, The Book of Rifle Accuracy is very informative. What is your Criterion's twist rate?

 

[hounddawg]

Sorry, 1-8, 26 inches. It shoots 69 grainers so so, .75 groups on average any bullet lighter than 69 won't group worth a damn. Loves 80 SMK's and Bergers also with Varget and CCI 400's, Federal, or CCI 450. I had one 300 yard match where 19 of the 20 rounds only had a 1 inch vertical, rest of the story is the group was 4 inches wide and centered on the 8/9 ring line LOL. Mirage? What mirage....ohhhh that mirage

 

[hounddawg]

Boyer's, The Book of Rifle Accuracy is very informative

Chapter 22 of that book explains the tuning of the groups. I will take the 21.5 load and bring the bullet closer and farther from the lands in .003 increments until it goes a tad vertical. I think it is pretty close now

 

[std7mag]

I'd play with seating depth at the 21.5gr charge, as you said.
Have you tried "tuning" your action?
Not sure how well it will work with groups like that already. I know my Stevens 200, and Savage 111 really came in. May help more with the larger volume cartridges.
I had to "retune" my Stevens when i switched from 7mm-08 AI to 250 Savage.

I've been hearing the 77gr SMK may stabilize in my 1:9 twist (advertised, i haven't had the time to check yet) barrel?
24" heavy.
LC brass
69gr SMK
3087fps with PP2000.

Planning on a 600 yard match, possably next month. If i could get the 77s to stabilize, i'd like to try them.

 

[edward hogan]

3087fps? Damn hot load you're running there with a 69gr .223/5.56
24gr Varget with 7.5rem primer and 75/77gr bthp is pretty much the classic match (SR) loading.
About 2700fps maybe 2750.

Never know till you try, I guess; re twist rate. 80gr bthp was usually favored at 600yds in Service Rifle, but had to be single-loaded due to VLC design of bullet. Probably no worries in a bolt rifle. The Tikka T3 mag could be modded to allow mag seating of the 80gr jobs. 1:8 twist very nice!