Dillon 550 650 Toolhead Clamp Kit Review

UniqueTek, of Gilbert, AZ, is a firm specializing in producing innovative reloading products. Most of their product offerings are geared toward reloaders who use Dillon Precision reloading equipment. Specifically, UniqueTek’s products are meant to enhance both the precision of loaded rounds and/or the speed of production using Dillon’s already excellent equipment. UniqueTek’s Chief Technology Officer (CTO), Lee Love, recently sent over a sample of one of their up and coming new products designed to enhance the Dillon 550/650 series of presses.

The product in question is UniqueTek’s 550/650 Toolhead Clamp Kit. Conceptually, the toolhead clamp kit is designed to “lock down” a toolhead in the Dillon 550/650 line of presses. According to Lee the thinking behind the toolhead clamp kit originated from the standard Dillon press and toolhead for the 550/650 series having relatively loose tolerances due to the manner in which both the toolhead and the press toolhead slot are machined, as well as the use of the stock drop-in pins to secure the tool head in the press. In a nutshell, Lee believes that, combined, the effect of the play between these two parts can cause appreciable variation in loaded cartridge overall length (OAL) due to the toolhead moving vertically and/or horizontally when the shellplate fully inserts cartridge cases into the toolhead’s dies at the top of the press stroke. This is not to say that the design of the standard Dillon 550/650 series toolhead and press is any way flawed, just that by their manufacturing tolerances they can contribute to OAL dimensional variation in reloaded cartridges. Likely this variation will be negligible, or have negligible effect on the performance of reloaded rounds. However, in the case of modern high-pressure cartridges, particularly certain handgun cartridges which seek to combine smaller case sizes with major caliber bullet velocities and energy levels, OAL variation needs to be minimized for safety’s sake.

UniqueTek Dillon 550 650 Toolhead Clamp Kit

Take for instance the 9mm round or the relatively newer auto pistol cartridges such as the .40 S&W and the .357 SIG. Each of these mid-caliber cartridges is designed to extract major caliber bullet velocities and energy levels from their relatively small volumetric cases. The benefits of marrying together major caliber performance with small cartridge size is readily apparent in these rounds being widely utilized by U.S. law enforcement agencies. These agencies lead the way in fielding semi-automatic sidearms which seek to strike the optimum balance between cartridge “horsepower”, high magazine capacity and relatively modest handgun size. Given the small internal capacities of these cartridge cases and the powder charges needed to drive their modern JHP bullets at high velocities, the pressures they generate are by and large at the higher end of the scale. As reloaders know, consistently controlling bullet seating depth, especially in small volumetric cases such as these, is crucial in order to keep reloaded rounds within safe pressure limits. A bullet seated too deep could likely cause a dangerous overpressure situation. UniqueTek’s toolhead clamp kit is designed to minimize this occurrence by rigidly holding a Dillon’s toolhead in place, and thus eliminating any possible vertical movement of the toolhead assembly as cartridge cases on the shellplate are being ran up into the dies. Any vertical movement of the toolhead assembly will likely cause OAL and crimp dimensional variations in reloaded rounds.

UniqueTek Dillon 550 650 Toolhead Clamp Kit

UniqueTek’s kit provides hardware and detailed instructions with which to modify a stock Dillon toolhead and convert it from being held in place with the Dillon stock drop-in pins, to being rigidly secured with threaded screws. ***NOTE*** THIS MODIFICATION DOES NOT REQUIRE THAT THE PRESS FRAME OR THE PRESS TOOLHEAD SLOT BE MODIFIED IN ANY WAY. Modification is made solely to the pin holes of the toolhead.

Briefly, the process for toolhead modification is as follows. A stock aluminum Dillon toolhead has the retention pin holes on its flanges drilled out with the supplied 9/64th” drill bit. The top of these newly drilled holes are very lightly chamfered with a ¼” drill bit. Once this is done a hand powered 5-40 tap is used to cut threads in the holes. Plenty of patience, a steady hand and liberal use of cutting oil are required so as to perform this step properly and not break off the tap in the soft aluminum material. After the threads are cut and the holes are blown out of all debris, stainless steel “helicoil” liners are then installed in the threaded holes with a supplied handheld tool. These stainless steel helicoils are of a harder material than the aluminum toolhead and act as a “sleeve” which the hex head screws will lock up with a bit later on. To those familiar with reworking automobile engine heads, you will probably recognize the concept behind the use of helicoils for this application. If not for the helicoils, the act of repeatedly screwing and unscrewing the steel retention screws as the toolhead is installed/removed from the frame would strip the threads in the soft aluminum toolhead. After the helicoils are in place the modified toolhead is reinstalled in the press along with the appropriate dies and power measure assembly, the user lightly threads the supplied hex head screws and spring washers from the kit into the toolhead via the retention pin holes in the press. Once each of the dies are re-adjusted and each one has a case ran up in them, and with the press ram at the top of the stroke exerting maximum pressure on the toolhead assembly, the screws are then tightened down firmly with the supplied hex head wrench. This “locks” the toolhead into position at the press’s maximum mechanical pressure on the toolhead. To remove the toolhead in order to change over to another caliber, all the user has to do is unscrew the hex head screws and slide the toolhead out of its slot. Again, the press retention pin holes are not altered in any way. The hex head screws drop through these holes and screw into the modified toolhead’s helicoil-lined threaded holes. The UniqueTek Dillon 550/650 Toolhead Clamp Kit tested contained enough helicoils to modify six separate Dillon toolheads.

In practice, the modification of the toolhead pin holes and the installation of the helicoil sleeves proved to be somewhat of an involved and lengthy process. It is highly recommended that the user read the directions thoroughly in addition to obtaining the recommended wet and dry lubricants needed to properly bore and tap the holes in the toolhead. Additionally, I would recommend that the user have access to a drill press. Although UniqueTek’s instructions do not specifically call for boring out the toolhead pin holes with a drill press it is paramount that these holes be bored out absolutely vertical so that the subsequent thread tapping and installation of the helicoil inserts is performed properly, as well as to ensure that the threaded retention screws can be subsequently screwed in and out smoothly without binding. With Dillon toolheads running about $20 a pop at retail, why risk ruining one when trying to bore to the holes freehand with a hand drill? Once the 9/64th” holes have been successfully bored out, the process of cutting the threads is done manually with the supplied tap. The user needs to supply a handle for the tap as well as thread-cutting lubricant. UniqueTek offers an optional tap handle for approximately $3.00. Again, a steady hand and consistent pressure are required so that the threads are cut consistent with the vertical axis of the bored holes so as to eliminate cross-thread issues when installing the helicoils and threaded screws. After completing this step and cleaning out the threaded holes, the installation of the helicoils took a couple of attempts before they seated properly. The first attempt to seat them was unsuccessful with the helicoils not seating all the way down into the threaded holes due to the supplied helicoil installation tool losing proper purchase on the coils as I tried to screw them in (Lee Love advises that he’s subsequently redesigned the helicoil insertion tool to ensure that it maintains solid purchase on the helicoils). On the second attempt I was able to finally get them properly seated. Once the coils were installed the modified toolhead was ready to have the dies reseated and then the whole assembly reinstalled in the press. At this point the threaded hex head screws were dropped down through the press’s retention pin holes and screwed in slightly. They were not tightened down at this point. Four cartridge casings were progressively indexed through the loading cycle and only then, after each die had a case inserted and the shellplate was at the top of the stroke, were the retention screws tightened down hand tight.

UniqueTek Dillon 550 650 Toolhead Clamp Kit

For the purposes of evaluating the toolhead clamp kit I decided to measure the pre-and-post modification OAL for 9mm reloads to determine the extent to which the modification minimized or eliminated dimensional variances. I selected fifty once-fired, clean Remington-Peters headstamped cases from my 9mm brass bucket. I inspected each case prior to trimming them to the Speer manual’s recommended trim-to-length of 0.744”. I then chamfered the case mouths. By way of bullets, I used Speer Gold Dot 115 gr. JHPs to reload the cases with. I reloaded twenty-five rounds as I normally would with the stock unmodified Dillon toolhead setup. I sat aside the 1st through 4th rounds as well as the 22nd through 25th rounds loaded. Out of the remaining batch of seventeen rounds from the lot, I had a friend randomly select ten rounds for measurement. The reason I didn’t include the first four or the last four rounds from this lot of reloads is because I wanted to measure only rounds that were produced when all die stations were fully engaged and consistent ram pressure was being applied to the toolhead via the shellplate. The results are as follows:

UniqueTek Dillon 550 650 Toolhead Clamp Kit

At this point the toolhead was taken out of the press and the dies removed. As per the discussion above the UniqueTek Toolhead Clamp Kit was then installed and the modified toolhead reassembled and reinstalled back in the press. After getting the dies readjusted, I again loaded a batch of twenty-five rounds exactly as I had the first batch of twenty-five. Again I had my friend select ten rounds randomly from cartridge numbers 5 through 21 out of this lot as well. These ten randomly selected rounds were then measured. The results are as follows:

UniqueTek Dillon 550 650 Toolhead Clamp Kit

By way of OAL, the variation between the randomly selected pre-and-post lots was measureable. An improvement of 0.002” in the OAL statistical range was recorded. Overall, the spread tightened up by 0.002” as well. Lee Love indicated that customers usually see total OAL ranges of no more than 0.001” to 0.003” with the toolhead clamped, so in this regard I am of the opinion that my results are consistent with the experiences of other users.

From a theoretical standpoint I can certainly see where this type of modification has merit, as it is always advantageous to rigidly control dimensional precision and consistency in reloaded rounds. Does the average reloader absolutely need it though? At the risk of equivocating here: It depends. If I were progressively loading any of the higher velocity/smaller case volume cartridges such as the 9mm, .40 S&W, .357 SIG, etc… I would certainly modify my toolheads with the kit in order to minimize OAL variation. Similarly, if my goal is to progressively load high performance self defense/hunting rounds or match grade accuracy benchrest-type rounds I would benefit from the use this product in order to extract greater precision and performance from my loads – even if I’m using expensive “benchrest dies” – as these are moving vertically in the unmodified toolhead with every pull of the lever the same as standard type dies. On the other hand, if I were progressively loading mid-range loads for many of the relatively low pressure/larger volume cartridge cases such as the .45 ACP, or many of the straight-walled revolver cartridges, I probably wouldn’t bother with the modification due to pressures in these cartridges not being as impacted by modest OAL variations.

The average user should be mindful that there is some effort required to successfully perform these modifications. For those who are interested, but not mechanically inclined, I would recommend that they contact a local machine shop in their area, or any of their buddies who have might have good mechanical aptitude, for assistance in installing the kit properly on their toolheads so as not to ruin any. As an option, UniqueTek offers for sale OEM Dillon 550 and 650 toolheads with their Toolhead Clamp Kit parts pre-installed. UniqueTek is currently conducting market research to gauge the market for offering Toolhead Clamp Kit installation services on customer-supplied toolheads.

This product is but one of the many interesting and innovative products which UniqueTek offers reloaders and shooters. You can check out their 550/650 Toolhead Clamp Kit, as well as toolheads with the clamp kit pre-installed, at their excellent website: www.UniqueTek.com or you can reach UniqueTek’s customer service and technical staff at their corporate offices in Gilbert, AZ at: (480) 216-2041. UniqueTek proudly produces this product here in the U.S.A.

UniqueTek Dillon 550 650 Toolhead Clamp Kit

Reviewed By: B.T. Davis