The rifle has a 23.6" barrel. Shoots 150 grain bullet better than 180 grn. 165 grn are ok.

Here is what I want to know:
Other than spin rate, what does the twist effect? For example, is a 1/12 normally better with lighter bullets as far as accuracy is concerned whn compared to a 1/10? Does it make any noticable difference to a hunting application?

Please educate me on twist rate differences and expectations.
Thanks.

Terry

Twist typically only limits you at the top end of the bullet range for a given caliber... and a 1:12 in a 308 will do exactly that for anything over ~180. There are exceptions on the fast twist end of things that I wont get into here.

The spin rate is what stabilizes the bullet. If the spin is too slow for a given bullet, it wont stabilize properly and accuracy will suffer (at best) or not stabilize at all and "keyhole" (at worst). So the short answer to that part of your question is that yes, with a 1:12 you'll be better served by a bullet in the 165 grain range. I don't see this as having a huge impact in the hunting world, as anything you would/should use a 308 on can be killed just as dead with a 165 as it can with a 180. The 1:10 would stabilize a heavier bullet... but is it necessary? That's a decision only you can answer, since it's relative.

Thanks Strongbad. 180 is as large or larger than anything I will need. Guess just need to do more work on the loads.

Terry how do you like the gun. It is one I'm interested in.

I have a McMillan TAC-308 with 20" barrel and 5R rifling (1:11.25). I shoot a Hornady A-Max 155 gr bullet with 44 grains of IMR4064 powder. I get an average of 2700 FPS and excellent bullet stability. I shoot to 550 yards and only correct for wind and have little spin drift effect to that distance.

The 155 grain bullet is an awesome performer.

"Terry how do you like the gun. It is one I'm interested in."

I like it a lot! Bought new 2 years ago. It shot great right out of the box. I reload with 150 grn hornady sst and spire points as well as 165 Nosler accubonds and gamekings. These shoot great with varget and RL15. I have shot it only out to 300 yrds.


the ability to pre-set the trigger is great feature.

these are not light guns but I use it mainly from box stand situation. Very sturdy and well made. Hope this helps. I have not regretted my purchase.

The lower rate of twist will also lower operating pressure, at least to some degree. A 1:12 twist in a .308 tells me the barrel is optimzed for bullets in the 150-155 grain range, which makes sense considering the overwhelming popularity of that range of bullet weight in the .308.

I have a CZ 500 full stock .308 and it is a tack driver! Im pretty sure I've loaded 150s for it and most likely they are Hornadys. I love this rifle. I have had it for three to four years. It's become a beautiful safe queen. I don't even think I have a scope on it at the moment. Well if you need info on the load/s I've developed for it let me know. That info is upstairs in my office.

1:12 typically works with weights up to 178.