Chambering Benchrest Barrels

[Jud96]

I shoot short range benchrest and do my own work. One thing that’s new to me, is doing prefit barrels based off of a barrel that was originally fit to the action. One of the things I struggle with is getting the cone depth correct. I made a little cone shaped tool, but it rocks around too much in the cone.

How do you guys measure the cone?

Also, how do you guys measure the headspace? I plan to make a tool that shoulders on the barrel, and has either a micrometer head on it, or a digital plunge indicator so I can zero it out on the old barrel to match headspace.

I’m sure I’ll think of other questions, but I just finished chambering a new barrel last night and ended up having to test fit it to my action to check the cone depth. The tools and method I thought would work to match the cone depth to the old barrel didn’t work out. Luckily I checked the depth when I did because it already had .012 clearance. Any help and input is appreciated. Thanks!

 

[LVLAaron]

3 seashells

 

[LVLAaron]

With these two tools, I can do anything, including clock/time barrels the same.

 

[Jud96]

That’s the next tool I’m going to make. And get some ball bearings, or improve the cone tool I made

 

[LVLAaron]

I've since purchased gauges from BAT. They serve as a go gauge.

 

[Jud96]

I've since purchased gauges from BAT. They serve as a go gauge.

What kind of gauges?

 

[LVLAaron]

https://www.batmachine.com/product/thread-gage/

I plan on engraving the degree marks around them

 

[Jud96]

Oh I gotcha. That’s neat. I just measure pitch diameter. I want to make a tool that’s threaded and indexed, but can also be used to measure the headspace and cone depth

 

[Judd]

Ryan Pierce also sells the gauges…just nothing for the cone micrometer

Products - Gunsmithing Tools - Piercision Rifles

www.piercisionrifles.com

 

[DDT414]

I made a gauge that I use for head space (with a go gauge) and cone spec. I keep a barrel that is correct and use it as the barrel to compare to.

 

[LVLAaron]

ahhh the power fister!

 

[DDT414]

ahhh the power fister!

lol. Ya pretty fancy. I have a decent one to replace it with but it keeps going…..

 

[ridgeway]

I've posted this a few times. My HS tool will read from zero to 2". It uses inserts to measure cone length. One made for 30°, other for 25°. All made of 12L14, which is super nice to machine...you'd swear it's aluminum...haha(to my exageration).

 

[butchlambert]

Mine:

Works for headspace just using the tool on the right.

 

[LVLAaron]

I like the engine valve design a lot.

 

[gunsandgunsmithing]

Mine is flat, without the angle. It simply establishes a datum point on both bbls. If the angles are the same, they'll be the same dimension. Same goes for angled or balls. If the two angles aren't EXACTLY the same, it's just a generic datum, too. Digital indicator on top. Just very easy to zero it out is why.

 

[urbanrifleman]

Kelbly method.

Set the headspace. Set back of the tenon flat to the gauge. Set the micrometer stop to the number for the gauge stickout. Cut the cone until hits the stop. Done.

 

[Brandon_M]

This is how I reproduce bolt cones after I've had the action in hand once. My method won't give any valuable info by measuring a action. I wrap the tool with masking tape to help it stay centered in larger bores.

I duplicate headspace the same way.

 

[butchlambert]

This is how I reproduce bolt cones after I've had the action in hand once. My method won't give any valuable info by measuring a action. I wrap the tool with masking tape to help it stay centered in larger bores.

I duplicate headspace the same way.

I thread mine so I do not need to hold it on the barrel.

 

[Brandon_M]

I thread mine so I do not need to hold it on the barrel.

I do also, I have several. It can be a little time consuming to make all that is needed but they're super handy.