"How Do You Do That?"

With our Patented EDM Chambering Process, Your Barrel is Guaranteed to be a Custom Chambering which is Unique before all others. Each chamber is cut as center to the bore as possible. We can actually build a barrel around your chosen cartridge, or even your dies.. You won't find reamer marks in an O.T.T. barrel. Heres Why......

Unless specified otherwise by the customer we use Douglas XX blanks.

We also request two (2) dummy rounds with the largest grain bullet the customer plans to shoot. These are used as a model for the chamber.
We can also use your reamer, loading dies or, just the numbers written on a piece of paper if need be.

Using an optical comparator to measure key dimensions, such as the actual straight-line intersection point of the neck and shoulder, we find the TRUE angle of the shoulder. We then note the transitional radius from the neck to the shoulder-angle junction. All of this is written down in a notebook for further calculations. Simple trigonometry is used to find the end points in relationship with the radius so that they can then be applied to the chamber's profile.
That profile is then used to manufacture the two electrodes (roughing and finishing) used to cut the chamber.
Unless a 'Step Up' Design is specified, the barrel is turned to 1" diameter, then cut to length. The crown of the bbl is cut utilizing a four-jaw chuck and the crown is indicated within .0005" TIR.
In order to ensure a sharp crisp edge the crown is not deburred and is cut from the inside out so as to not roll a burr.
We take crowns very seriously around here and get them as close to zero as possible.

The patented EDM process allows custom chambering to be done very easily and with great precision. The process is stress-free. Moreover, since the electrode rotates while cutting, EDM guarantees a perfectly round hole which matches the cartridge exactly. Compared to using a conventional chamber reamer, EDM offers much more control over internal geometry. This allows us to refine the internal chamber profile.

EDM is an automated process that can run unattended. It utilizes electricity to disintegrate everything in the electrode's path, imprinting the electrode's profile into the parent material. The machining takes place on a molecular scale, the grains and structure of the workpiece are heated to beyond their critical temp in the gap via sparking action. The removed metal is then carried away as smoke within a dielectric insulating fluid. Finish cuts can be as low as .001" per inch per side. The actual recast layer is less than .0001" after a finish-cut cycle. This is easily removed by lapping compound.

EDM chambering begins with production of specifically-sized electrodes. The electrodes are cut basically to include the throat length and a given lead-angle length. This area is left .001" undersize and lapped to size, this also allows as much material to be removed as possible. The electrodes are made of high-grade graphite to minimize wear. The finish electrode is usually the same size as the cartridge. However, if the customer desires tighter clearances, the electrode is sized accordingly.
The electrodes are indicated for less than .001" TIR; .0005" or less is optimum. The bore centerline where the bullet is to sit has already been positioned with a probe, electrically-finding center. The roughing electrode was set to the desired TIR and was positioned using a gauge block and the end of the barrel. The original notebook dimensions used for electrode manufacture are used again to program the depth stop on the EDM. Coolant is provided to insulate the cut from the muzzle end of the barrel as the EDM is basically running in reverse.

Setting the finish electrode is the same as the roughing, but we use a lower power setting to control the overburn from electrode to work-piece. When the barrel is done, it is again indicated in a four-jaw chuck lathe so that the chamber can be finish-polished.
Polishing is done with wooden chopsticks and two grades of lapping compound--one for roughing, one for finishing. This allows the recast layer of the cut to be smoothed up to enhance case extraction. This method cleans up the surface uniformly. It is not able to take a cut so you do not have to worry about the problems you can get with emery paper or honing stones. At this point all that is left is hand-lapping the throat diameter and leade angle. One degree per side is the norm for taper.
After the lapping is complete, barrels are drilled and tapped for sights/mounts and fore-end.
Barrel surfaces are then blasted in preparation for the final black-oxide finish.

During chambering/ assembly we pay special attention to geometry and stress-avoidance.
For example
While chambering the barrel, it is suspended via a magnetic V-block, precision-ground for squareness and perpendicularity. This way there is no stress to the barrel from clamping. The only stress barrels see is during profiling, TIG-welding the lug (T/Cs) and finally, drilling and tapping sight and fore-end mounting holes.
Every barrel produced by OTT LLC is treated and cut this way, delivering a truly custom-chambered barrel that exactly matches the ammunition. This, in turn, has produced very accurate barrels.

The T/C Encore® and Contenders® can be very accurate if the critical areas of performance are consistent. Those areas can be broken down into good quality handloading components and practices, good barrel assembly with a chamber that matches the ammunition, and finally, a shooter that is consistent in his/her method of shooting.
The barrel assembly is the only area that OTT, LLC can have an impact on. We treat that assembly as a precision piece of equipment, there is a lot done within the design to ensure the system will actuate and operate in the same manner each and everytime. With the exception of the barrel and locking lugs, everything is designed and manufactured 'in house'.

Here the barrel lug is key to accuracy. It must be precisely positioned and sized. The lug is manufactured complete prior to turning the barrel. Some businesses machine their lugs after welding to the barrel. By contrast, we machine lugs complete prior to welding so that the relationship of hinge-pin hole to locking bolt slot is the same on all lugs. Set screws are used instead of roll pins so that no hammer is needed to assemble or disassemble for later servicing. The hinge-pin hole is left .001" undersize from Wire EDM so that it can be lapped to size prior to fit-up. The lug is heat-treated complete and left slightly long for frame-gap grinding after welding. Once the barrel assembly has been ground to the ideal frame-gap dimensions and lug-finish thickness, it is ready for chambering. Finally, the lock-up is adjusted so that all the gun barrels (when the gap is ground) will lock up the same and the customer should never have to adjust locking bolt heights.

We have eliminated the variables created from the use of reamers and various aftermarket components (Forends Excluded) Our patented process allows us to build truly custom 'ultra accurate' barrels as a rule, not an exception. Working with tight tolerances is the norm here, if you want a tighter than SAAMI Chamber just let us know.
Compare the holes with any other barrel on the market today. You will then see for yourself why On Target Technologies has the confidence to claim.....

Ultra Accurate Custom Barrels...Each and Every Time... Guaranteed