What is "The Bellm Protocol"?|
In short, it is simply a few basic remedial steps proven to be necessary to make the break open TC guns functional and accurate.
|It consists of these easy, do-it-yourself steps:|
Click on the links below to get to the pages you are being referred to.
|Tighten the fit at the hinge first off.|
|Measure and correct headspace|
by means of
|Shimming the firing pin bushing with Bellm headspace shims|
and learning how to properly adjust the case resizing die if you reload.
"Common Wisdom" developed over the years for other types of guns does not apply to the break open guns.
One beautiful feature of the TC break open guns is the ability to not only measure the headspace of each and every round you shoot if necessary, but the removable firing pin bushing lets you quickly and easily adjust the headspace, particularly with factory ammo or new brass that gives too much headspace.
|Install our stronger hammer spring|
The factory hammer spring is simply marginal at best. It is too weak if you want to use a hammer extension, there is much headspace, or you are shooting ammo with "hard" primers such as military type primers.
|Lighten and smooth the trigger to a manageable level|
A heavy, rough trigger pull will simply not let you do your best shooting.
We are the source for instructions, tools, and springs for doing your own trigger work.
|Bed the forend for consistent fit on the barrel|
There are several schools of thought regarding forend bedding, but the main point is to float the barrel so it only contacts the forend in a small area round each forend screw and NOWHERE else.
Bedding bar systems work well much of the time, but pillar bedding seems to work most consistently if full, tight contact with a synthetic forend does not produce good accuracy.
|Follow the links above and the successive page links you find on those pages for reliable functioning and reaching the accuracy potential of every barrel you shoot, doing the work yourself.
|The steps above are to "tune" the gun as a system of barrel, ammo, frame, and forend.
Below are the next steps that may require machine work to fix.
1) Recrown the barrel. The TC factory has only rarely put out barrels with crowns that are cleanly cut and square to the bore. Bergara has been far, far more consistent with good quality crowns, but as with any production item, there are instances where there is need for improvement. We check and touch up the crowns on the Bergara barrels we sell as standard procedure. Even some of the better custom made barrels can stand improvement, and each barrel must be taken on an individual basis.
2) Correct the throat IF possible by rechambering to a longer cartridge that will cut out the defective throat and permit cutting a new throat that IS aligned with the bore and is cut minimum diameter. In many instances such as with .270 Winchester for example, there are no longer rounds that are suitable for the Encore.
3) Correct the lockup of the barrel if there is any hint of it being loose. We have come to specialize in correcting lockup of loose fitting barrels and feel this is one aspect of Encore and Contender accuracy that has long been overlooked. The barrel MUST be pulled down tightly in its seat in the frame.
We make this correction by either fitting larger locking bolts or forging the lower lip of the barrel lug upward slightly, rehardening it, drawing it back to proper hardness, then recutting the slot higher in the barrel lug.
|Click here for one method of precision recrowning|
Longer barrels can be put through the headstock of the lathe and dialed in to get the bore running on axis with the machine for crown cut that IS centered with and square to the bore. The cut itself comes out on an 11 degree angle.
|Study the pages linked to below to better understand the importance of good machining techniques properly applied to barrels, as well as examples of what you commonly buy unwittingly thinking you paid good money for a good barrel.|
|The accuracy role the throat plays, click here. |
See this page to better understand just how important the throat is and to see how pitiful many throats are. A "perfect" barrel otherwise with a bad throat translates to bad results no matter what you do.
|Click here for some typical examples of misaligned throats.|
Sadly, some of the most well known TC barrel makers, including and especially Thompson Center itself, put out some horribly misaligned chambers. For many, many years Thompson Center merely stabbed a chamber reamer at a barrel in a drill press. These earlier production TC barrels are some of the very worst examples in the industry. But even today, when the bore is dialed in in the lathe, there is normally anywhere from a few thousandths to up to .025 to .030" runout in the mouth of the chamber.
Even the untrained eye that knows what it is looking at can readily SEE the misalignment very plainly. In fact, your eye can pick it up quicker and easier just looking into the bore than it can with a bore scope. Where the throat cut ends, there is normally a line in the grooves of the barrel connecting the ends of the rifling. If that line does not appear symmetrical from groove to groove, it means it is not cut to the same depth, which in turn means it is off center. A centered throat will show a uniform depth of cut into the groove area all the way around.
However, if the groove diameter of the barrel is larger than the throat reamer cuts, there will be no connecting line, as is often the case with the minimum diameter throat reamers I use.
|Remedial barrel work and custom chambering by Mike Bellm|
Click on the link above to my Barrel Work page.
|To your best success shooting the TC break open guns,