Measure freebore, will this work?

[Riesel]

OK, got back to the shop to test this theory, didn't work. Not even close. Used a reamer print as the overall cartridge length and still no quevo. I'm still wondering if there is a way to measure freebore on an unknow barrel and chamber.
I appreciate everyone's input. I know I wasn't drinking when I came up with this idea so maybe it's just my age.

 

[Rich S]

A couple of thoughts:
1) If you have a chamber of know free bore you could compare the two. Seat the same bullet & case to touch in each gun and measure the difference with your Hornady comparator. This only works if the throat hasn't eroded on the know chamber.

2) Send a dummy round with the bullet seated to touch (or even better, a cast of the chamber) to JGS. They use a optical comaprator to get accurate measurements. They offer this free if you are buying a reamer. Not sure what they would do if not buying a reamer. They have made a couple of reamers for me based on a dummy round and the finished chambers matched very close.

Neither of the above will give you the true free bore number listed on the reamer print but should get you somewhat close. You really get CBOT and are back calculating free bore. The differences would be the case lengths (dimension U on a reamer print)

 

[Dusty Stevens]

You could seat a popular bullet and use the wheeler method of finding the lands, set it to exactly touch then use a hornady comparator to take a measurement and see if somebody has the same stuff and a chamber of known freebore they could do the same with and compare measurements.

 

[Riesel]

A couple of thoughts:
1) If you have a chamber of know free bore you could compare the two. Seat the same bullet & case to touch in each gun and measure the difference with your Hornady comparator. This only works if the throat hasn't eroded on the know chamber.

Thanks for your comment. This is exactly what I did using a barrel I chambered with a know FB of .090 and measuring the new barrel. The new barrel was .080 longer for a total FB of .170. The 208 Hornady Match is a nice fit and I plan to start there with a good dose of Varget/
Best Regards,
Robert