Contender G2 .223, Really Bad Accuracy

[Larry Gibson]

Measured twist is 1:12

Okay then, with the 12" twist given a nominal 3200 fps then the bullets, if longer than .740", will exhibit poor to nonexistent accuracy. Bullet stability with a given caliber, twist rate and velocity is determined by bullet length not bullet weight. For example, M193 55 gr FMJBTs which normally stabilize in a 12" twist at 3100 fps have a length of just under .740". Where Sierra 55 gr Blitz bullets have a length of .805" and give very poor accuracy in my 12" twist rifles but excellent accuracy in my 7 - 9" twist rifles. They are just too long to stabilize in the slower 12" twist. Thus I suggest you continue to use bullets not longer than .740" in length.

[hylander]

Okay then, with the 12" twist given a nominal 3200 fps then the bullets, if longer than .740", will exhibit poor to nonexistent accuracy. Bullet stability with a given caliber, twist rate and velocity is determined by bullet length not bullet weight. For example, M193 55 gr FMJBTs which normally stabilize in a 12" twist at 3100 fps have a length of just under .740". Where Sierra 55 gr Blitz bullets have a length of .805" and give very poor accuracy in my 12" twist rifles but excellent accuracy in my 7 - 9" twist rifles. They are just too long to stabilize in the slower 12" twist. Thus I suggest you continue to use bullets not longer than .740" in length.

Thanks Larry,
Now I have to go measure my bullets.

[Barry54]

https://bergerbullets.com/twist-rate-calculator/

60 grain Nosler Partition bullets are short for their weight if you are looking for a sturdy design.

[hylander]

Just back from the range.
I adjusted head space to .001 with my reloads.
Installed a Bellm oversize hinge pin, which greatly cut down on side to side play when action is open.
Lapped the Crown, which looked very rough.
This time she shot respectable groups under MOA, except for the 40 Nosler, which I am going to blame the bullet as they have not shot very well in any of my rifles.
I also had switched scopes. However, after seeing all was well, I swapped the Leupold back on and it is fine.
All is right with the world 🌎.
I am thinking the main issue was the crown.
I might have my smith cut a new crown.
Again barrel is 1:12 twist.
Length of the bullets I shot today:
Hornady 55 V-Max = .811
Sierra 55 HPBT = .715
Nosler 40 Balistic Tip Lead Free = .783

[Dusty Bannister]

If you get bored with the improved accuracy, you might try the old hinge pin just to see if that made any difference in groups. Just curious if that might have been a factor.