Finally arrived! Optimal bore diameter?

[Justice1327]

Finally got some more of my Mullerworks Barrel in and primers. Gonna be a busy fall/winter.

Something I just noticed, but why the difference in the increase in bore groove to lands? In other words who determines and more specifically, how was it determined that that specific increase is best for that caliber? Why not .004 increase for all calibers?
For example:
200 - 204 : 4thou
219 - 224 : 5thou
236 - 243: 7thou
250 - 256: 6thou
256 - 264: 8thou
277 - 284: 7thou
300 - 308: 8thou

 

[Phil Rizzo]

Excellent question.

VinceMule?

 

[MagnumManiac]

Depends on interruption stresses on the jacket, the thinner the jacket the least 'squish' is desired.

Cheers.

 

[ARlife4me]

the larger the bore the more difference between groove and lands the is. like @MagnumManiac said above is key. the larger the caliber it can handle more separation due to less deformation and more hold is needed thru torque (ie, deeper grooves). slower cartridges of the same caliber can also have less separation like ballard rifling or micro-grooves.

 

[stazmania]

Pressure make velocity. loosening or constricting make a lot of difference. You could/can adjust with burn rate and volume of powder. But why? I am sure this has been tested and optimized. but if you can find improvement for even a specialty discipline that has not already been discovered, that would be awesome. If no one ever questions or tries how would anything ever be discovered or improved. Great thought.

 

[Justice1327]

Depends on interruption stresses on the jacket, the thinner the jacket the least 'squish' is desired.

Cheers.

Yeah, I thought about that but who determines how thin a jacket should be and most people don't even know how thick a bullet jacket is. I don't believe there's an industry standard.

 

[Justice1327]

Pressure make velocity. loosening or constricting make a lot of difference. You could/can adjust with burn rate and volume of powder. But why? I am sure this has been tested and optimized. but if you can find improvement for even a specialty discipline that has not already been discovered, that would be awesome. If no one ever questions or tries how would anything ever be discovered or improved. Great thought.

Yeah, my only experience with this so far has been a .218 bore compared to a .219 bore for 22 caliber centerfire. I always air on the side of caution and get a 219 bore but now that I'm shooting more 20 caliber I'm wondering if that bore Diameter is Ideal

 

[338 dude]

Finally got some more of my Mullerworks Barrel in and primers. Gonna be a busy fall/winter.

Something I just noticed, but why the difference in the increase in bore groove to lands? In other words who determines and more specifically, how was it determined that that specific increase is best for that caliber? Why not .004 increase for all calibers?
For example:
200 - 204 : 4thou
219 - 224 : 5thou
236 - 243: 7thou
250 - 256: 6thou
256 - 264: 8thou
277 - 284: 7thou
300 - 308: 8thou

I wouldn't mind running across a few thousand CCI 250s myself!

 

[MagnumManiac]

Yeah, I thought about that but who determines how thin a jacket should be and most people don't even know how thick a bullet jacket is. I don't believe there's an industry standard.

These things were deduced just after jacketed clad bullets were invented. With lead, it didn't matter and most rifling profiles were Ballard type, same width for land and groove. Many attempts since have focused on skinny lands and wide grooves for less jacket obturation.
Whether there is a 'standard' or not, SAAMI clearly lists WHICH type and size they want…

Cheers.

 

[ARlife4me]

I wouldn't mind running across a few thousand CCI 250s myself!

go on ammoseek and there are some 250's in stock

 

[ShtrRdy]

I'll add a tidbit to the topic. The short range benchrest shooters shoot a 6mm bullet and believe the best bore diameter is 0.237". The groove diameter is the standard 0.243".

 

[MagnumManiac]

I will add, personally, I prefer Ballard type rifling with 4 grooves, nearly all having .008" deep grooves, except for my 17's and 22's.
Have used 3, 4, 5, 6 and 8 grooves and one micro-groove which I will never do again…you want fouling, do this.
4 groove barrels have always been more precise for longer with every build I have used them in.

Cheers.

 

[Justice1327]

I will add, personally, I prefer Ballard type rifling with 4 grooves, nearly all having .008" deep grooves, except for my 17's and 22's.
Have used 3, 4, 5, 6 and 8 grooves and one micro-groove which I will never do again…you want fouling, do this.
4 groove barrels have always been more precise for longer with every build I have used them in.

Cheers.

Yes, i have used a Mullerworks 4 groove before, but just shot factory ammo. I'll give these go and see how they do for Accuracy and Precision.

 

[FEENIX]

I will add, personally, I prefer Ballard type rifling with 4 grooves, nearly all having .008" deep grooves, except for my 17's and 22's.
Have used 3, 4, 5, 6 and 8 grooves and one micro-groove which I will never do again…you want fouling, do this.
4 groove barrels have always been more precise for longer with every build I have used them in.

Cheers.

I have two 3Gs from Lila in .27 and .30 cals and am very pleased with them thus.