Barrel Change on Ruger American

[Capbyrd]

33 minutes ago, maroonandwhite said:

Basically in the picture showing the threads, it is just started on the threads. One concern is that I won’t have many threads engaged. The other concern is that on the flip side of that those threads will be exposed inside of the flash hider. 

I'm NOT an engineer, but I think that you only need like three fully engaged threads to have full clamping force.  

However, seating on the shoulder of the barrel is likely to introduce some concentricity issues. The threads might be concentric to the bore but the shoulder concentric to the OD. 

AAC latches are known to fail and the day has long since passed being able to get them serviced.  Having the can converted to accept any of the modern adapters is likely a good idea.  They cut the end off and thread the end of the tube to accept any of the new mount styles (I still think YHM is a good one but everyone loves the taper mount these days).  I know that BSD Fabrication and Ecco Machine do good work on the AAC cans. 

  

[Capbyrd]

6 minutes ago, maroonandwhite said:

I think the suppressor was always going to be somewhat of a bonus on this gun anyways. With 26” of heavy on the end plus another 9” , it’s just not too practical. I may just put the cap on it and call it a day.  I don’t feel like having to deal with poi shift anyways.

Certainly looks better to my eyes without a flash hider.

Might I recommend another option, if you aren't going suppressed?  

PRS EC Tuner Brake 1.100″ diameter – Cortina Precision (shootsmallgroups.com)

[maroonandwhite]

3 minutes ago, Capbyrd said:

Might I recommend another option, if you aren't going suppressed?  

PRS EC Tuner Brake 1.100″ diameter – Cortina Precision (shootsmallgroups.com)

That’s pretty snazzy. I may look into that once I shoot it a bit and see how it does. I can’t imagine I’ll need any sort of recoil reduction from a brake but it would be cool to increase accuracy any little bit.  

[Capbyrd]

Just now, maroonandwhite said:

That’s pretty snazzy. I may look into that once I shoot it a bit and see how it does. I can’t imagine I’ll need any sort of recoil reduction from a brake but it would be cool to increase accuracy any little bit.  

If you don't want a brake, there are tuners available without them.  But I think Erik's tuners that aren't a brake are made for a different thread style and would require the barrel being worked. 

[maroonandwhite]

2 minutes ago, Capbyrd said:

If you don't want a brake, there are tuners available without them.  But I think Erik's tuners that aren't a brake are made for a different thread style and would require the barrel being worked. 

I’ll be using this in a deer blind and brakes have never been friendly to confined spaces. I have started wearing ear protection when hunting without a suppressor but still, it can get loud. Having never fired a round of 6.5 Creedmoor in my life, I don’t really know what to expect apart from ballistics.

[Capbyrd]

8 minutes ago, maroonandwhite said:

I’ll be using this in a deer blind and brakes have never been friendly to confined spaces. I have started wearing ear protection when hunting without a suppressor but still, it can get loud. Having never fired a round of 6.5 Creedmoor in my life, I don’t really know what to expect apart from ballistics.

 

 

I totally understand.  For a purely hunting rifle, a tuner might not be necessary.   Minute of deer is good enough.   If you want to take it to the range and try to squeeze the smallest groups out of it, it seems like all of the top competitive shooters are running tuners.   

[OldIronFan]

15 hours ago, Capbyrd said:

I'm NOT an engineer, but I think that you only need like three fully engaged threads to have full clamping force.  

However, seating on the shoulder of the barrel is likely to introduce some concentricity issues. The threads might be concentric to the bore but the shoulder concentric to the OD.  

I am an engineer and three threads is a common rule of thumb that works in many applications but it is a generalization. It does not take into account coarseness of threads (TPI) and major diameter. The 3 full threads rule of thumb is based on an 80% hold strength. There is a point of diminishing return where the added strength/benefit of additional threads is diminished for each additional thread. 

You absolutely want the muzzle device seated on the shoulder of the barrel. The shoulder is not concentric to the OD, in fact barrel OD is irrelevant  unless you have a fit over / fit in requirement. The shoulder must be perpendicular to the bore axis. The typical GD&T call out for the shoulder is a max of .001 or .002 perpendicularity to the bore. Similarly the mating face of the muzzle device has a typical perpendicularity call out of .001 to .002 max to the internal thread depending on manufacturer. 

Concentricity must be held between the muzzle thread OD and bore axis as well as the muzzle device thread ID to  both the external adapter thread OD and the muzzle devices bore axis. Again a quality manufacturer is going to spec/hold .002 to .003 max concentricity on those features. If there is a tapered seating surface for the engagement of the suppressor on the muzzle device it also must be held concentric to the muzzle device internal thread. Our call out for that is .002 max to the internal thread. 

[Capbyrd]

2 minutes ago, OldIronFan said:

 

You absolutely want the muzzle device seated on the shoulder of the barrel. The shoulder is not concentric to the OD, in fact barrel OD is irrelevant  unless you have a fit over / fit in requirement. The shoulder must be perpendicular to the bore axis. 

You're right, I was thinking of something else when I added that part.  Oops. 

 

[maroonandwhite]

Thought I would post the happy news on this situation. Since the 51T AAC adapters have finally com back in stock, I was able to get a proper brake for this barrel.  Since it doesn’t have the same design as the flash hiders (recessed threads) I was able to thread it all the way back to the shoulder. So now I can add even more weight to this already heavy monster!

[maroonandwhite]

And the 5.56’s can play too!