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About Corbin Press Adapter Bushings

The CSP-1 S-press has a 7/8-in x 14 tpi (threads per inch) head, and does not accept larger bushings. It can be used directly, as it comes, for reloading with standard 7/8-14 dies as well as bullet swaging, jacket drawing, bullet reducing, and a limited range of small diameter lead wire extrusion.

The CSP-2 Mega Mite has a 1-1/2 in x 12 tpi head, but comes with a 7/8-14 adapter bushing called the "RLA-B" (Reloading Adapter Bushing). You do not have to purchase one separately to use standard reloading dies.


The CHP-1 Hydro Press also has a 1-1/2 in x 12 tpi head, and also comes with the free 7/8-14 adapter bushing (RLA-B). All Corbin swaging presses will accept standard 7/8-14 reloading dies. All the presses also come with an adapter for the ram, to accept a standard RCBS-type button shell holder. The larger presses include a ram extension adapter which can accept optional 7/8-14 threaded shell holders as well as the standard button shell holder adapter. So, all Corbin swage presses are ready to use with RCBS-style button shell holders (T-slot base) regardless of the fact that the rams have either 5/8-24 or 1.0-12 threads for Corbin swage dies.

Bushings and custom head plates are available, or made to order, to accept different thread sizes.

In the CSP-1 S-press, with standard 7/8-14 head, the only practical way to change thread size is to produce a custom head plate for you. Removal of the head requires careful realignment, which is greatly assisted with the use of a special alignment tool made for either the standard head (if you wish to restore original configuration) or the custom thread size. Such alignment tools are generally found on the webstore, as options, when you order the special thread adapter bushing. Replacing the head also requires special technique, and the right tools, such as a T-handle socket wrench and a plastic faced mallet, and should not be done casually. Heads are aligned by diemakers before the press is shipped. Head changing is not usually recommended, but it can be done with care by a person with good mechanical ability and the proper tools. However, the CSP-1 press can be ordered with a custom head, made and assembled before shipment, and left in this configuration without any problem. A 7/8-14 bushing may be used to bring the thread back to standard size without risking misalignment.

In the CSP-2 and CHP-1 presses, with standard 1-in x 12 thread, a series of adapter bushings can be ordered or custom made if needed, up to a maximum of 1-1/4 x 12 inch. Larger bores or the 1-1/4 x 14 thread will require a custom head plate. The reason a 12 tpi thread works in an adapter and a 14 tpi thread requires a new head plate is simple: there isn't enough metal left between the inside 1-1/4 inch x 14 thread roots and the outside 1-1/2 inch x 12 thread roots as they cross each other. But in the 12 tpi pitch, the threads can be synchronized so that the inside and outside thread roots are opposite the peaks of the other thread, maintaining a constant wall thickness by this trick of expert machining.
Adapter Bushings

  • RLA-B Outside = 1.5 x 12 tpi, Inside = 7/8 x 14 tpi.
    This adapter is comes with the CSP-2 Mega Mite and the CHP-1 HydroPress, but is also available separately on the webstore. It is part of the reloading adapter kit, which also includes a ram extension with primer port to adapt the ram from 1 x 12 tpi to 7/8 x 14 tpi, and a t-slot shell holder adapter with 7/8 x 14 tpi base. All items are shown on Corbin's web store at SwageDies.com.



  • CHP-B2 Outside = 1.5 x 12 tpi, Inside = 1.25 x 12 tpi.
    This is the largest adapter bushing that can be used in the CSP-2 and CHP-1 presses. Larger sizes require a custom head plate. It is used for some of the less standardized 50 BMG and similar large caliber reloading dies. (Most 50 BMG dies and similar large calibers made today use the same 1.5 x 12 tpi thread as comes standard in Corbin's larger presses, so no adapter would be needed for RCBS, Hornaday, C-H 4D, and most other major brands. But check carefully: some earlier dies or dies from some manufacturers have been made with other threads. Dies made in 1-1/4 inch diameter can have either 12 pitch or 14 pitch threads. Only the 12 pitch thread works in this adapter.



  • CHP-B1 Outside = 1.5 x 12 tpi, Inside = 1.0 x 14 tpi.
    According to Huntington Die Specialties, makers of custom sized reloading dies next to the RCBS plant in Oroville, California, some of the larger caliber die sets (such as Safari Series and Group X dies) are or have been made with a 1.0 x 14 thread. This bushing adapts not only Corbin CSP-2 and CHP-1 presses to handle these dies, but also works in the Rock Chucker Supreme and possibly other presses such as the RCBS AmmoMaster-2 single state press.



  • CHP-B Outside = 1.5 x 12 tpi, Inside = custom, less than 1.25 diameter.
    For special diameters that are smaller than 1.25-inch, your custom threaded insert can be ordered from the webstore. Almost any thread can be made to order so long as it is smaller than 1.25 inches. For instance, 1-1/8 x 14, 1 x 12, 7/8 x 12, 5/8 x 24 or 3/4 x 14 are some of the threads people have requested.



Other Adapters

Some of the other kinds of adapters for Corbin presses include the following:
  • CHP-S2H Ram adapter, 1.0 x 12 tpi (M) to 5/8 x 24 tpi (F)
    This adapter allows the use of 5/8-24 threaded jacket draw punches, which screw directly into the ram of the CSP-1 press, to be used in the CHP-1 and CSP-2 presses (which have 1.0 x 12 threaded rams). This also makes the cost of the draw punches less because they can all be made with a smaller threaded base, even if they are for exclusive use in the larger presses due to the length of draw, reducing the heat-treatment complexity and time as compared to making a full 1-inch threaded base on long, thin punches. As most machinists know, heat treating steel parts which have a large mass on one end can be very tricky. Also, honing, lapping, polishing, and even shipping and handling such a part makes it more prone to accidental breakage than if the mass is more evenly distributed. By making the base a separate part, the bulk of the weight is self-contained and separated from the punch. Your drawing punches are lower cost, once you have even a single adapter base, since all of them can use the same part, reducing production time and cost and improving strength. When you buy a jacket drawing set for the larger presses, we normally provide one CHP-S2H adapter plus as many drawing punches as required for the job. You can also use this base for other items such as Arbor Press Anvils, but not for -S type swage dies (which require a more complex kind of adapter to operate the internal punch). Please note that the image is typical but not necessarily identical to the one you receive, as the height may need to be greater for some operations, and checkering may or may not be needed or desired for others.



  • RLA-EXT 1.0 x 12 (M) to 7/8 x 14 (F) ram adapter
    This is also called the "reloading adapter ram extender" because it increases the height of the ram for the CSP-2 and CHP-1 press, allows for a spent primer port in the side, and holds a T-slot shell holder adapter called the RLA-H so you can use standard RCBS-type button shell holders in the larger presses. This part comes with the larger presses, in the reloading adapter kit, but it is available separately also.

    Another version of this part, which is machined with a hole all the way through it in addition to having the primer port on the side, is used as part of the Corbin PT-50-H primer seating tool. The tool includes a 50 BMG shell holder, a primer seating punch which operates inside the ram, and a primer guide sleeve which can be removed to use the assemly for de-priming fired cases. These two parts are NOT interchangeable but they look almost identical. The dimensions are somewhat different and there is a hole through the base of the primer tool component which is not present in the adapter.



  • RLA-H 7/8 x 14 (M) to T-slot shell holder ram adapter
    This is the standard shell holder adapter with a 7/8-14 threaded base, which screws into the RLA-EXT ram extender/adapter in the larger Corbin presses. It allows the use of conventional button shell holders of the RCBS style. Spent primers pass through the hole and into the angled port area in the extender, and then roll out the side of the extender. A neat trick you can use with very little cost is to get a 3/4-inch or larger diameter thin walled plastic tube, long enough to reach the floor from the top of your press. Split one end for about 2 inch length of cut. Place the two cut end flaps around the ram extender so the primer hole is lined up with the tube, see where you should poke a hole through both split ends to clamp them around the adapter unit, and secure the ends with the bolt and nut to hold the tube firmly in place. As you de-prime cases, the spent primers will now roll down the angled port and into the tube, which is large enough so just the motion of going up and down with the ram will move the primers through it, and into a waste bin into which you place the other end!



  • CSP-1R 5/8 x 24 (M) to T-slot shell holder ram adapter
    This is the combined ram extender/spent primer guide/shell-holder adapter unit for the CSP-1 S-press. One comes with each press, but they are available separately as well (see SwageDies.com secure web store for prices and details. The purpose is, of course, to allow standard RCBS-type shell holders to be used in the CSP-1 press. The press also needs to be set in the long-stroke mode by moving the ram to toggle pin into the second, longer stroke producing set of holes. In this mode, you have a 4-inch ram travel rather than 2-inch for swaging. However, don't forget to move it back when you are through reloading! Also, the stop pin in the front of the press must be pulled out or it will limit the stroke and cause you to pull out some hair before you realize why it can't be there for reloading...unless your solution to any problem is more force, in which case it will be bent or broken by attempting to push the ram past it.



Other Adapters

To see the other adapters available, and pricing on press heads, look on www.SwageDies.com, then Presses, then S-press accessories for the S-press, and on www.SwageDies.com, then Presses, then H-press accessories for accessories for the -H type presses (CSP-2 Mega Mite, or the CHP-1 Hydro-Press).

Corbin Presses CSP-2 Mega Mite Other Topics


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About Corbin Arbor Press Adapters