| Use your Bellm
Headspace Indicator to measure case heads for square-ness to the
breech-face and also compensate for out of square case heads by
proper size die adjustment to get correct headspace.
One of the characteristics of all the TC break open guns is the
fact that both the barrel and chamber are not square to the breech-face.
Typically, the only time a chamber would be square to the breech
face would be if its misalignment with the bore resulted in it accidentally
being square to the breech-face.
You can readily observe this fact. In fact, you have seen it, but
probably had no clue what it meant.
You have no doubt seen a rub mark in the finish on the end of the
barrel just above the chamber on barrels with virtually no barrel-to-frame gap.
The fact that the barrel only hits the firing pin bushing in the breech-face at
the top of the bushing indicates the barrel is dropping into the frame to a
point below square to the bushing/breech-face.
When the pressure is sufficient to push the case head back hard
against the breech face, the head will be bent out of square to the rest of the
This means that if you have a batch of fired cases with
heads out of square with the breech-face, the high spot will rub hard on
the breech face closing the barrel in a random manner depending on how the
case is rotated when chambered compared to where it was when it was fired.
This points up one more reason to full length resize
cases and leave about .001" actual space (headspace) between the case head
and breech face.
Getting away from this is impossible unless a barrel is
made with the vertical location of the hinge pin hole exactly correct to
cause the barrel to drop into the frame's barrel seat exactly parallel to
As it is with most barrels, the hinge pin hole is lower
on the lug than it should be for this to happen. The result is it holds
the barrel up in the frame at the hinge pin area and lets the barrel teter
over the seat at the rear. This is the reason why the actual contact point
marks on the barrel are normally only at the extreme rear of the seat even
though the seat is much, much longer than the marks left on the barrel.
Again, the best you can do is to resize your cases so that the case
head is not being pushed on by the firing pin bushing in a random direction
depending on where the high spot on the case head happens to land.
This is just a fact of life.
The location of the hinge pin hole is necessary to allow for the
wide range of fit on the thousands of frames they might be used on. It is
there by design and is pretty consistent on all TC Contender/G2 and Encore
barrels, including most all custom after market barrels.
Back in the 70s & 80s, one shop used to clamp the barrel into a
frame at the barrel seat, then use a taper reamer to ream both the frame
and barrel hinge pin holes at the same time, thus creating a perfect
height of the hinge, BUT ONLY FOR THAT ONE BARREL DEDICATED TO THAT ONE
FRAME. A tapered hinge pin was also used.
Reaming a barrel like this also then ruined the barrel for use on
any other frame unless another frame could be successfully reamed larger
in the same manner and fitted with a tapered hinge pin.
While it produced some outstanding guns that showed up mostly on
the silhouette ranges, it was not done very commonly. Once in awhile one
still crops up, but they are relatively rare, and I do not recommend going
to this extent. One can do it, and under some circumstances, I might
consider doing it, but normally no. Like I said, it is pretty much a one
way deal, and it defeats the attractive interchangeable barrel feature of
the TC guns.
If you care to do so, marking your cases for orientation in the
chamber or only loading and shooting all cases with, say, the caliber on
the head-stamp positioned at the top of the chamber then shooting reloaded
cases with the head-stamp turned 90 degrees, 180 degrees, 270 degrees,
etc. may demonstrate the effect the out of square case heads rubbing on
the breech face is having on accuracy.
Again, correct resizing for proper
some space, may well be a real key to accuracy in any given barrel
chambered for a bottle neck case.
Give it some thought and better yet, rotating your Bellm Headspace
Indicator over cases in the chamber will show if one edge of the head is
higher than the rest of the head.
Paying attention to this characteristic of the TC break open
barrels may turn out to be a means to improving accuracy or solving more
severe accuracy problems.