Before and after blueprinting action: Results?

[BCIII]

How much does truing the action really affect performance? Have you blueprinted an action that you previously fired and were able to observe a performance enhancement?
I just picked up a new 700 to tear apart for a build. I can have it blueprinted for $300. Is it worth it?

Side note questions on bolts: One piece or two piece? Why? And O.D.: Manufacturer asks .6995 to .7000. Why? What is .0005" going to achieve? What do I specify?

Last question, another side note: I'm building a .260. Twist options are 1:8, 8.5 or 9. It appears that 8.5 twist are the most readily available (Bartlein). Is 8.5 appropriate for 140 grain? I think I read 1:8 for 140 and above and 1:9 for 120-130. So If I'm planning on using 139-140, is 8.5 ideal?

I really appreciate any input. Sorry to load multiple questions in one thread, but figure it is more efficient. Thanks.

Barney

 

[Fjr86]

Whether or not blueprinting if worth it to you depends on what you want out of it.

I assume you intend to pick up an aftermarket bolt then. I chose 1 piece as I believe it is stronger than bolting 2 parts together.

M700 can have varying bolt channel ID. They recommend to size your bolt channel and then get a bolt a couple thousandths of an inch smaller. I believe they varied from .695-.700. At least they are the offerings from PTG. The idea is that the bolt can not be canted if the bolt has tight tolerances with the bolt channel from the chamber. Sizing the bolt to the bolt channel is basically doing the same thing people do when they get their bolts sleeved.

 

[ShtrRdy]

Is the $300 for truing the action only? If so, that's kinda high. The LRI group buy ended up with a truing cost of $125.

As for twist, I can say from experience that the 8.5" works okay with a 140 gr in the .260 Rem. But that's at 5000' +/-

 

[sentry1]

How much does truing the action really affect performance? Have you blueprinted an action that you previously fired and were able to observe a performance enhancement?
I just picked up a new 700 to tear apart for a build. I can have it blueprinted for $300. Is it worth it?

Side note questions on bolts: One piece or two piece? Why? And O.D.: Manufacturer asks .6995 to .7000. Why? What is .0005" going to achieve? What do I specify?

Last question, another side note: I'm building a .260. Twist options are 1:8, 8.5 or 9. It appears that 8.5 twist are the most readily available (Bartlein). Is 8.5 appropriate for 140 grain? I think I read 1:8 for 140 and above and 1:9 for 120-130. So If I'm planning on using 139-140, is 8.5 ideal?

I really appreciate any input. Sorry to load multiple questions in one thread, but figure it is more efficient. Thanks.

Barney

I would go with the one piece, because the cost difference is minor ($30 more for the one piece I believe, when you add up the costs of the two piece plus having the bolt handle attached to the body), and if you have a stuck bolt, breaking the handle isn't as big a concern.

I think it's hard to see how much truing the action really affects accuracy, because it's generally accompanied by a new barrel as well, so there's a few variables changing all at once. It would be interesting to see some controlled experiments on how these modifications affect performance.

My rifle just got worked on, but I have no baseline to compare against at all, because it went from .308 to 6.5 Creedmoor.

 

[6.5BR]

I ALWAYS choose 8 twist for ANY/ALL 6mm and 6.5mm.......a 9 will work sometimes or most of the time, thru 142s - depending on variables, an 8.5 is common and usually does well, but the 8 is clear cut never marginal for any reason.