Progressive Versus Single Stage
Comparison Between a RCBS Rockchucker Press
and a Dillon 550B
By Joe Gorman
There's something ingrained in our psyches that makes us equate slow, monotonous crafting with high quality and high speed production with lower quality. Even when technology enables us to create high quality products at tremendous quantity, we tend to be a bit suspicious. This is nowhere more clearly visible than in reloading. At one time, any match shooter you would ask would tell you he reloads on a single stage press. Today most shoot progressively reloaded ammunition.
Last year I wrote an article about long range .45 ACP shooting. A couple home brews I came up with gave tremendous accuracy. I used range brass, paid no special attention to my RCBS Piggyback II and came up with one loading that drilled five 185 grain Speer SWCs into .61" group (center to center measured) at 25 yards. I'm sure some readers thought I spent all night trimming brass to consistent length, chamfering, measuring each powder charge individually, etc. Nope. I didn't even polish the brass. I didn't even segregate brass by manufacturer.
So what is important in reloading? Volumes and volumes have been written about the precision ammo crafting. Substitute a few words here and there, and you may as well be reading a book about designing rockets. But does it really matter? let's find out.
How about we take some new brass, single stage load with a proven target load and see what happens. Then we take the same load and the same new brass and load it up on a progressive. Which load will be more accurate? Ok, you say. But I seldom shoot brand new brass. How about a rifle caliber and a pistol caliber loaded up with once fired brass? Done. I'll load up some .45 ACP with new and range brass and some .223 with once fired commercial brass. I'll go the shooting range, benchrest and sandbag the guns, and fire five, five-shot groups of each type and record the results.
Test Bed Weapons
Of course, a prerequisite for testing ammunition is an accurate firearm to test them. For the .45 ammunition I will use a Colt Special Combat Government from Colt's Custom House. For the .223, I'll use a Colt Competition Sporter (Flat-top).
The Colt Special Combat Government started life as a pre-enhanced government model and then went under the skilled hands of Colt's custom gunsmiths. The sights are Bo Mar adjustable. The trigger is a Videcki and the trigger pull measured a perfectly crisp 5 pounds. The grip safety appears to be a Ed Brown as does the ambidextrous thumb safety and the hammer. The mainspring housing is a flat, Smith and Alexander design with integral mag well funnel (I replaced it with an arched Smith and Alexander with integral mag well).
Of course the Colt Custom Shop doesn't just throw some aftermarket parts on an old Government model and jack up the price. This pistol has also been hard chromed, had all the working parts hand fitted, and been range certified. Mine was shipped with a target that stated it had been fired at 15 yards with Winchester Silvertip ammo. It looked like one ragged hole. This is a world class pistol folks. I shot a 2.5" five-shot, off hand, center to center measured, group at 50 yards with Federal Match 185 grain SWC ammunition the day I unpacked it. (I've not equaled this feat since, but at least I know the pistol is capable of this kind of accuracy). Colt made a pistol that surpasses the sum of its parts for less money than many of its competitors Custom house offerings. The trigger pull is just heaven.
But you know me better than to think I could just leave well-enough alone. Bill Laughridge at Cylinder and slide installed one of his stainless tactical thumb-safeties (I personally do not care for ambi-safeties) This is a low profile, extended thumb-safety that allows good purchase yet won't come off accidentally. He also got the trigger weight down to around 3.5 pounds. I also installed an Ed Brown two-piece full-length recoil spring guide rod. I then rigged the Colt Special Combat Government with an NPC grip mount and a Redfield 2x scope mounted with 1" Redfield steel rings. (I had to put on a Colt standard thumb safety temporarily while the NPC was on as it was the only safety that would fit with the NPC was in place.)
The Colt Competition Sporter (Flattop) .223 is a 1/9 twist, heavy barrel AR-15A2 that sans the bayonet lug. The removable carrying handle allows mounting scopes, with X-tra high rings, at the same height as the regular iron sights. (Infinitely preferable to the usual mounting in the carrying handle I think) Right from the box this rifle would routinely throw sub-inch, five shot groups at 100 yards. The only problem was that one group might go .80" and the next group might go 1.3".
I free floated the barrel with a D.P.M.S. fluted-aluminum forearm tube. This did not make the rifle any more accurate, just a heck of a lot more consistent. Now, if I shoot five shots over 1" using Winchester .69 grain BTHP Match ammunition, I don't blame the rifle. I secured a set of MWGs excellent X-tra high, steel tactical rings right to the top of the flattop's receiver. These rings are milled from a solid block of forged steel, secure with a socket wrench and lock-up tighter than Hillary come election time. Usually, I keep a Tasco Super Sniper 10 power scope on top of this rifle as this scope is about as rugged as the MWG rings. For this testing I decided to replace the Super Sniper with a Pentax 6-24 Variable Power Light Seeker target scope. This Vari scope is clear throughout the entire power range and is bright even at 24 power. I figured the high powered Pentax would take out any alignment variables at 100 yards (With this scope I can sight off .22 caliber bullet holes)
The Presses and Dies
RCBS Rock Chucker is perhaps the most ubiquitous press on reloader's tables. The familiar green, cast press is a solid, fool proof performer that will last for generations of reloaders. Like many reloaders, the Rock Chucker was my first press. When I clean it up it still looks new. This is after more than 100,000 rounds loaded. I know this because I save the 5,000-quantity primer box tops. Rock Chucker is also flexible enough to, with the addition of an RCBS Piggyback II, become a progressive loader. I've loaded a number of rounds on the Piggyback II and it works well for an add on. I've found it requires frequent readjustments but it does what it says it will.
The Dillon 550B is listed as the most popular progressive loader in the world. I have no reason to doubt this claim. The 550B is sturdy and easy to set up. It does not automatically index to the next stage as does the Piggyback II, but this can be a blessing, especially when first setting up and adjusting dies. All adjustments are easily made and seem to, at least in my limited experience with it, hold well. I loaded a couple hundred rounds of .45 Colt and .45 ACP on the 550B and the large primer seating punch broke. I then switched to load .223, loaded about 150 rounds and the small primer seating punch broke and I ruined several cases during the powder charging station. The case mouth was getting crunched. All of these failures were due to me not quite having everything aligned properly. There is a learning curve on this press. Once I got everything zeroed in, I had no more problems.
I use RCBS dies for all reloading. For the .45 ACP I used RCBS Carbide dies and a carbide seater/taper crimp die. These dies require no pre-lubrication and have proven to be very durable. The seater/taper crimp die makes quick work of loading, especially when single stage loading, and in my experience makes for accurate ammunition.
Once again, my definitive research has produced more questions than answers. In .223, the results were as amazing as they were puzzling. The 62 grain Speer FMJBT with the penetrator tip, produced some ho-hum results when loaded single stage. But loaded on the Dillon, I produced the most accurate .223 ammunition I've ever fired through the AR! In fact, I used mixed, multi-fired brass in the Dillon and shiny once-fired, same manufacturer brass in the single stage. I Didn't change the loading 24.5 grains of WW748, using CCI's 5.56 primers designed specifically for the .223 for either load. There is something about the process within the Dillon that is very repeatable.
One of those processes that seems to be more repeatable is the powder measuring. There seems to be a sort of damping that takes place on a progressive. Possibly all that linkage helps even the arm stroke out. But there's got to be more to it than that. Is it bullet crimp tension? Is it case mouth expanding? I wish I knew!
What I do know about this load is that when loaded single stage it is capable of five shots into just over an inch at 100 yards. When loaded on the Dillon, it goes five rounds into under half an inch. No special attention to detail, no special attention to brass, (remember, mixed commercial) just incredible groups. It could very well be something I did incorrectly on the single stage But one thing is for sure: the Dillon progressive is capable, very capable, of producing incredibly accurate rounds.
In .45, I loaded up Speer's 200 gr. FMJ SWC over 6.7 grains of Unique and WW magnum or standard primers. This load has proven accurate and reliable and came out a little more accurately when loaded via single stage than those loaded on the Dillon, but not by much. When new brass was used, the groups were a couple hundredths of an inch tighter. I would have thought this would be more significant., considering my used brass varies greatly between number of firings. (Some of this brass looks like a new caliber, it's so shortened from use!)
The best five-shot group I could manage with the single stage reloaded ammo was a ragged hole measuring .77 inches, center-to-center. As I mentioned the Dillon-produced-ammo shot groups that were typically very close to their single-stage-produced brethren but a couple hundredths larger, coming in at .92 inches. This is probably statistically identical in terms of accuracy, I'm sure human error at the trigger could account for this.
So what can one glean from these results? Progressive loaders are not a compromise in terms of accuracy. In fact, in light of the .223 loads I made on the Dillon, an argument could be made that progressive loaders are capable of producing more accurate ammunition than single stage presses. Easier, quicker and better?!
As is true with so many things these days, it simply does not pay to fear technology.