Upgrading the Arcus Pistol

In June 1923, a patent application was filed for a 9mm Parabellum semi-automatic pistol. The patent (#1618510) was granted in February 1927, just three months after the inventor’s death. Here’s how that gun is described and how it works: It is recoil-operated with a locked breech, an exposed hammer, and reloads itself after each shot until the magazine is empty. The ribs on the barrel’s breech end engage similar grooves in the slide that firmly lock the two together at firing.

The breechblock is integral with the slide, thereby sealing the breech against forces expected when the gun is discharged. Recoil continues with the breech sealed until the bullet exits the bore. At that millisecond, the rear of the barrel is cammed down to disengage it while the slide and breech block continue to the rear. Extraction, ejection, and reloading of the pistol from a fixed magazine are close to being identical with the inventor’s other breech-type pistols.

Its safety systems block the hammer, sear, and include a magazine disconnect. Sound familiar? It should. It was the last semi-auto handgun designed by the immortal John M. Browning. Initially produced in quantity by Fabrique Nationale in Belgium as the GP 35, the pistol is far better known as the Browning Hi-Power. The gun remains in production with a retail price of around $800. That’s for anew-in-box, untouched pistol.

The pistol pictured here is a clone of the original Browning design with the exception that its thumb safety blocks the hammer rather than the sear. Outside of that and some minor cosmetic refinements, the Arcus has been made by the Bulgarian company with the same name since 1994. It’s produced’quite nicely, I would say" in both single-action (Model 94) and double-action (Model 98) versions. The latter has an additional "firingpin safety mechanism." By that, I assume the manufacturer means "firing-pin block.

Both models are sold for import to these shores. The Model 94 I worked with for this article was imported b tional Arms, Inc. Although there are other sources of Arcus pistols, I have a good reason for including Century Arms’ phone number in the previous paragraph. The reason is that the price of a Browning Hi-Power is too high for some customers to bear. But you can suggest that the customer buy an Arcus, and save him about $500 over the cost of a Browning.

And then you can suggest that he use some of that savings to pay you to make some upgrades to the Arcus pistol. In fact, he might get carried away with the upgrades’as some customers do’and you could make a lot more than if you’d sold him a Browning in the first place. This limits to some degree the steps you can take in performing a significant upgrade to its function as a personal defense handgun.

While it’s advertised and sold as a "true clone" of the BHP, I was anxious to find out if the Arcus would accept parts made to the Hi- Power specifications. These would include the aftermarket upgrade components sold b Slide that I wand love, as well as the non-restricted items that are available from Browning and Brownells. Since I didn’t have a Hi- Power in the shop at the time I was writing this, I asked Jim Garthwaite, Pistolsmith of The Year for 2006, to help me out.

Jim builds top-notch custom Hi-Powers and usually has more than a few on hand. He sympathized with my predicament and agreed to check out the Arcus Model 94. I shipped the Arcus to Jim’s Pennsylvania base of operations, and just in time for me to complete this article, Jim emailed me with his observations. I’ll condense those observations here and add some additional information gleaned from my discussions with the technicians at Cylinder & Slide who work on BHP pistols everyday.

So here’s the deal: Most BHP parts will interchange nicely with an Arcus. But there are some exceptions. The sear lever in the pistol presents problems (to be discussed later) and the Arcus barrel is .650 shorter. A BHP barrel will install in the slide and will work, as long as there’s no objection to the muzzle not being flush with the end of the slide.

If this is judged to be unsightly by the custom- Arcus Model 94 9mm Semi-Automatic Pistol (Specifications subject to change without notice) 1 Slide 2 Barrel 3 Frame 4 Slide Stop 5 Retaining Plate 6 Firing Pin 7 Firing Pin Spring 8 Firing Pin Retaining Plate 9 Extractor 10 Sear Lever 11 Sear Lever Pin 12 Disconnector Lever 13 Front Sight 14 Rear Sight 15 Recoil Spring 16 Guide 17 Guide Spring 18 Guide Ball 19 Trigger 20 Trigger Pin 21 Trigger Spring 22 Trigger Lever 23 Trigger Lever Spring 24 Magazine Latch 25 Sear 26 Hammer 27 Safety 28 Follower er, the Browning barrel would have to be cut back to the proper barrel length and recrowned, with shorter recoil springs installed and the recoil guide shortened accordingly.

All this is possible and not too difficult to accomplish. What isn’t so simple is modifying the frame’s recoil lug. No small task that. Extremely precise measurements of the barrel’s recoil lug must be taken. After that, the frame lug has to be machined, stoned, and polished just as precisely. The question that must be asked is this: Since adapting a BHP barrel to the Arcus frame is unlikely to produce a significant gain in accuracy, is the added expense really worth it?

Because there’s nothing wrong with the Arcus barrel and because the pis- 29 Follower Spring 30 Magazine Housing 31 Magazine 32 Sear Spring 33 Strut 34 Main Spring 35 Follower Spring Support 36 Magazine Bottom Plate tol is intended primarily for close-in personal defense, I would say "no." On the Other Hand" But I’d answer with an unequivocal "yes’ if the customer asked me for a smoother, crisper, lighter trigger pull. Here you have some choices.

The original Arcus trigger system components appear to be machined of goodquality material, so you could opt to work with them. Or you could substitute and rework Browning factory parts, assuming that the factory sear and hammer aren’t castings. If they are, they won’t hold their tolerances for an extended period of time after stoning. Or the better option would be to use nothing but aftermarket upgrade components. ¨

Complete "how to" instructions are widely published and not included here for that reason. I’ll tell you why I’d go in that direction. The Cylinder & Slide sear is CNC-milled, treated to 52 RC, and will maintain the stoning applied to its engagement surfaces indefinitely. That stoning on the sear and other trigger-system parts would be accomplished with the help of an old friend of mine’t he Ron Power Custom Series I Stoning Fixture.

I’ve used this tool for hammer/trigger/sear work on more than a dozen different handguns, and my confidence in and satisfaction with this tool is complete. There’s nothing more that needs to be said about this tool; Ron provides comprehensive instructions with every fixture he or Brownells ships out. In addition to the sear, I’d order a 54.5 RC hammer, and an extended slide release and springs’which I did for this Arcus.

I did not include a wide combat trigger, however, since installing such a trigger would have made it necessary to defeat the maga- Point "A" identifies the nose, and point "B" is the paddle. Installation of this significant upgrade is not recommended with the Arcus pistol for reasons stated in the text. The feeler gauges and adaptors are not included with the fixture. All adaptors are firearm specific. B Azine disconnect, and I never defeat a safety or any part of a safety system on any gun.

Caution on Cutting the Sear The Ron Power instructions will provide the step-by-step "how to" information, but be careful not to overdo it. And watch that sear pin. It’s under plenty of pressure from the hammer spring and removing too much sear material will allow the spring to win. The pin will become bent. Cut a little, install the sear and carefully cock the gun. If you meet up with stiff resistance in the cocking, back off quickly.

Remove the pin and roll it on a true surface such as a square of plate glass to ensure no bend is present. Then, maybe, you can stone the engagement surface a wee bit more before running another test. I know that all this installing, disassembly, reassembly, and testing is tedious and can wear you down. Do it anyway. Almost nothing can ruin this particular upgrade like a bent sear pin. Every tolerance you’re working toward will be thrown out of whack. Install a New Sear Lever?

If the Arcus was a clone of the Browning Hi-Power Mark III, there’d be no problem with installing anew sear

The removal of very little material will be all that’s required. lever and no reason not to, and the trigger would be further improved. But with a Mark II clone such as the Arcus, that isn’t the case. There’s no accommodation for the bend in the lever or the paddle that serves as a firing-pin stop in the Arcus (see the photo above). Sure, those modifications could be made by machining a cutout in the center rail of the slide for the bend, and grinding off the paddle. But I chose not to do that on this pistol. Why?

The reason I chose not to install the lever was the fact that the out-of-box trigger pull on the pistol was not that unpleasant. it was a reasonably clean-breaking 7 pounds" not 8, 9, or 10"and that was decreased to an infinitely smoother and crisper 5 pounds as a result of the stoning, spring work, and polishing I did. Actually, the pull felt more like 4 pounds. But make no mistake about it’on a Mark III or a Mark III clone, the sear lever would have improved even on that.

A Final Check-Point Does the thumb safety move into its slide notch? Good. It’s supposed to. But when it does, is it blocking the hammer? Insert a magazine, cock the hammer, and pull the trigger. If the hammer follows, the safety isn’t moving far enough up into the slide. The photo shows the area that material should be taken from. Usually, it only amounts to a couple of thousandths. Need I say go lightly with a smoothcut file and check your progress often? I thought not. I