# New Bore aligning system.



## GummyMonster (May 6, 2022)

Morning everyone,
 I follow this fellow on gavintube and making with metal channels. He seems very knowledgeable and constantly in pursuit of accuracy, in shooting and metal work. There's been lots of discussion about alignment on lathes, so I thought it would interest some of you.
 He's started selling these. 




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						Long range custom built rifles
					

Custom rifles built to your specifications




					www.straightshotgunsmithing.com
				




And more pics and info here - https://makingwithmetal.com/true-bore-alignment-system-in-depth/

Not cheap, but accuracy rarely is.
Ken


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## Susquatch (May 6, 2022)

GummyMonster said:


> Morning everyone,
> I follow this fellow on gavintube and making with metal channels. He seems very knowledgeable and constantly in pursuit of accuracy, in shooting and metal work. There's been lots of discussion about alignment on lathes, so I thought it would interest some of you.
> He's started selling these.
> 
> ...



I spent quite a bit of time looking at this system a while back. For someone who trues and chambers 24/7 it might pay. But it has no real operational advantage over a good spider system - sometimes called a cat's eye. 

@thestelster shows how this is done on another thread.

I have built about 6 fixtures to do this kind of work over the years, each a step better than the one before. I understand the drivers for doing it. But I think the objective gets lost in the fancy fixture sometimes. I also think that we are easily lured into buying gizmos to help us do something we don't fully understand. 

I was pleased to see the designer acknowledge the importance of concentricity and the usual ways of dealing with it. But I think he places way too much importance on the distortion caused by the jack screws in a typical spider. The true bore system uses 6 jaws instead of 4 to counteract that effect, but it is still there. On the other hand the designer describes why a spider isn't as good but fails to fully assess the system. A typical spider has 8 jack screws with 4 of those located well behind the machining area. With an 8 screw spider you use the rear screws to provide the drive forces and concentricity and the front screws only for concentricity. It's also common to use larger buttons to spread the forces, and I go a step further with collars. 

The point I am making is that I think the main advantage of the true bore system is setup speed and convenience. There is no real stress or distortion advantage over the more traditional spider system. Done right, the spider system is superior in that regard. 

It's an excellent idea and a very cool fixture but I prefer the raw performance of a spider system over the convenience of the true bore fixture.


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