Reloading Precision 7mm PRC on Dillon 550C Progressive

Can you make match-winning precision ammunition on a progressive press? The conventional thinking is that you have to use a single-stage press to load precision ammo, but I won my 2023 national championship after loading everything on a Dillon progressive press. That’s right, not only is it possible, but I’ve done it. Today I’m sharing some tips and tricks for loading precision 7mm PRC ammunition on the Dillon 550C.

Disclaimer

Ultimate Reloader LLC / Making with Metal Disclaimer: (by reading this article and/or watching video content you accept these terms). The content on this website (including videos, articles, ammunition reloading data, technical articles, gunsmithing and other information) is for demonstration purposes only. Do not attempt any of the processes or procedures shown or described on this website. All gunsmithing procedures should be carried out by a qualified and licensed gunsmith at their own risk. Do not attempt to repair or modify any firearms based on information on this website. Ultimate Reloader, LLC and Making With Metal can not be held liable for property or personal damage due to viewers/readers of this website performing activities, procedures, techniques, or practices described in whole or part on this website. By accepting these terms, you agree that you alone are solely responsible for your own safety and property as it pertains to activities, procedures, techniques, or practices described in whole or part on this website.

About the Equipment

Progressive presses are able to complete multiple tasks at one time with one stroke of the handle, while single-stage presses only perform one action with each stroke. This makes them significantly faster and more efficient, saving the user time and energy. There are a variety of different progressive presses ranging in sizes and capabilities. The Dillon 550C has four stations, allowing four actions to be performed simultaneously.

I personally use the Dillon XL-750 for greater volume, but I believe the 550 is a better press for loading precision ammunition. The brass directly touches the platform below the shellplate on a 550 whereas elevated shellplates on other presses leave room for deflection. This hard stop leads to greater consistency across all actions. The 550 also has the widest array of caliber conversion options and is one of the most cost-effective Dillon machines.

For this demonstration, I’m loading 7mm PRC with Forster Ultra Dies using ADG cases, Vihtavuori N565 and Berger 7mm EOL Elite Hunter 195 grain bullets.

Press Setup

Some don’t see a need for sizing virgin brass. I always make a habit of it to ensure every piece is perfectly matched to whatever die and chamber I am using.

I raised the ram and screwed the Forster full-length sizing die down until it touched. I then lowered the ram, tightened it another quarter turn, and secured the die into the press.

I set up the Forster full-length sizing die so that it makes contact with the brass, even if it doesn’t bump the shoulder at all. After I fire the cases for the first time, I will readjust the sizing die. Sizing dies should never be set up and forgotten about — they always need adjusting.

Most dies will have a replaceable bushing that controls the neck diameter of the brass. This allows the user to swap out bushings if desired.

When using a die with a bushing, I tighten the stem then back it out just a bit, just enough to hear the bushing rattle if I shake the die. This little bit of float will prevent shoulder damage and encourage self-straightening.

Secondly, I set up the Dillon powder measure to drop the desired amount of N565. I primed a case for this step to keep the powder contained and placed it under the powder funnel.

It took a few adjustments to the powder bar to drop the desired charge. I loaded three different charge weights: 55.0 grains, 58.0 grains, and 61.0 grains. Before loading any rounds, I verified the desired charge weight several times. This is very important.

Setting up the sizing die came third. I loosened the die lock ring and ran a piece of brass through the first few steps: priming and charging. I placed a bullet atop the charged case, raised the ram, and raised the die until the press handle fell without moving the seating die at all.

At this point, I screwed the seating die down until I could feel it touching and adjusted the die until I barely seated the bullet.

I then checked the overall length with a set of calibers and continued to adjust the die further until I reached the desired 3.375” OAL.

If needed, use the tip of the bullet as a reference marker when adjusting the micrometer seater.

Larger adjustments are best made by loosening the lock ring and screwing the die down further. Smaller adjustments can be made with the Forster sizing die micrometer AFTER the die touches the shellplate.

Loading Demo

With all the dies set, it was time to load. (I did make changes to the powder drop when I changed charge weights.) First came resizing in station one.

Priming happens when lowering the ram after sizing in station one. Station two dropped the powder, station three seated the bullet. This left one empty station in the press.

The 550 is a manually-indexed press, meaning that I had to rotate the shellplate each time. This served as another opportunity to verify each step of the process.

I loaded 10 rounds with 55.0 grains N565, 10 rounds with 58.0 grains, and 10 rounds with 61.0 grains. I also have three “blow-off” rounds from set-up that are not the exact overall length I will use for fouling.

Shooting

7mm PRC isn’t a cartridge I’ve spent considerable time with, but it is one I do enjoy shooting. I used Gavin’s 7mm PRC long action on this range trip. This rifle is centered around a BAT HR (long action) with magnum bolt face bolt and 28” Bartlein barrel, complete with custom Cerakote and laser engraving.

It has worn a few different “clothes” but is currently set in a UD7 chassis with UD spigot (extra 3.25” of ARCA), UD adjustable buttstock, and Bix’n Andy Remington 700 TacSport trigger. I shot five rounds of each load through the magazine off a bench at 100 yards with a front rest and rear bag, recording all the shots with the Longshot LR-3.

The 55.0 grain and 61.0 grain groups were the best. I then transitioned to the second target after letting the gun cool a bit, shooting the remaining rounds, but this time single-loading each cartridge. All of the groups followed the same trend, four shots touching and one flier off to the top left. I believe this is shooter error.

My groups were not phenomenal, but they were still good. Most promising was the 61.0 grain load, which held a small group with a hot barrel, indicating it is a stable load.

Conclusion

I was really impressed with the 100 yard results, especially given I have had little experience with the cartridge, used what I consider a thrown-together hunting load, and assembled it all on a progressive.

This experiment is just another vote of confidence in progressive presses for precision reloading purposes. For someone looking to reload a variety of precision cartridges,the Dillon 550 provides the best value, balancing affordability with features that greatly expedite the loading process.