free bore

[Link]

Can we measure free boar by loading a specific bullet into a case then chamber it ?

Measure from the neck to where it first touches the lands on the bullet when jammed [marks] = free boar?

thanks Link

 

[FergusBailey]

Only if you know for a fact that the neck is right on its full length for the chamber – if the case is trimmed shorter than max for the chamber, you will be including some of the chamber in that measurement. And then recognise that the section from the hypothetical case neck end to the lands will include both free-bore and lead for example my 6PPC reamer has a free-bore of 45 thou, and a further 10 thou of lead. Using the approach you describe, this would look like 55 thou of free-bore. Plus there is some further inaccuracy introduced from measuring jam marks.

 

[LCazador]

You can't measure free bore that way because you're actually measuring at the a point on the ogive not on the bearing surface . It makes no difference how long the case is . The only was to measure free bore is to make a chamber cast or contact the reamer manufacturer .

 

[gotcha]

I'd agree w/ the cerrosafe method for the most exacting measurement. Other than cerrosafe you could get a rough estimate of free bore by using a (Sinclair chamber length gauge). Just use the search feature @ Sinclair for description. This little tool will establish the exact length of your chamber to the end of the neck. Next, size a case then slit the neck w/ a Dremel cut-off wheel to allow a slip fit for a bullet. Get a flat based bullet & seat it backwards. Chamber it to seat it against the taper of the lands. Subtract the chamber gauge meas. from the seated bullet meas. for a rough estimate of free bore.

 

[bigedp51]

I have an AR 15 with a military chamber and a Stevens 200 in .223, by just bumping a fired case in a resizing die and seating a bullet long I found out my Stevens has a longer throat or freebore than my AR 15.

Then I did some Google hunting and found this

SAAMI .223 freebore .0250
Military 5.56 freebore .0500
Savage .223 freebore .0566

Therefore you can compare your freebore to like rifles and be in the ball park.

If your a fan of freebore you can buy old British Enfield rifles that used Cordite powder and have all the freebore you will ever need. ;D (freebore humor)