A 10mm 1911

I recently found a Rock Island Armory 1911 Ultra FS 10mm for sale on Gunbroker.com. It was marked down to an unbeatable price by one of my favorite sellers, so I pounced.

This after I’d said–not for the first time–“I don’t need any more guns!”

My excuse

We hiked Yellowstone and Grand Teton National Parks this fall. The parks were gorgeous–and they offer free passes to veterans.

There were already snow flurries in the higher elevations, and rangers warned us that grizzlies (!) were coming down from the mountains to fatten up for the winter.

Should you encounter one of these giants, the National Park Service recommends bear spray as a last line of defense.

I wanted something more definitive.

If you’re going to carry a firearm for bear defense, experts recommend a rifle (or shotgun loaded with slugs) with a large caliber handgun for backup.

Rather than alarm my fellow vacationers unduly, I passed on the rifle/shotgun option and settled for bear spray and a Ruger GP100 in .357 magnum.

Although the .357 is supposedly on the light side for big bears, with its six-inch barrel my GP100 is anything but: big, bulky, and awkward to conceal under clothing.

It’s a great firearm, but there’s nothing discreet about it.

Back home while researching alternatives to the big revolvers, I discovered that the 10mm auto–after being largely abandoned by the FBI in the 1990s–is experiencing a renaissance among outdoorsmen.

The cartridge has ballistics comparable to–or even superior to–the .357 magnum, depending on loads. The Rock Island 10mm is smaller and slightly lighter than my GP100, carries two more cartridges, and is easier to reload.

I can be a bit of a gun snob, but Rock Island/Armscor has been making 1911s for decades and according to their many fans these entry-level firearms punch well above their weight.

So I went for it.

Setup

The pistol was shipped to a local gun store. After filling out the necessary paperwork I raced home, then retired to the garage for the unveiling.

The first order of business was to wipe off the thick packing grease.

Next I measured trigger pull weight. The trigger was surprisingly good for this price point: a decent break, averaging about 5 1/2 lbs–although I noticed a few excursions above 6.

There was a fair bit of pre- and overtravel. I reduced the overtravel with the included adjustment screw: to do this, turn it clockwise until the trigger doesn’t work, then back it out one full turn. Use blue Loctite to fix it in place.

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Time to disassemble the pistol! (p.s., if you’re not a 1911 expert, YouTube is your friend).

The Ultra FS in 10mm auto uses a bushingless design. The recoil spring on the full-length guide rod has to be restrained by a paper clip inserted into a hole drilled in the rod for that purpose (paper clip not included) to remove the slide.

If you remove the paper clip to inspect the spring (or because you’re curious), you’ll find it difficult to compress the spring enough to put it all back together.

Luckily I happened to have a plastic bolt gauge handy: the 3/8″ hole was just the right size to allow me to compress the spring with one hand and reinsert the paper clip with the other.

I may drill a 3/8″ hole in a piece of scrap aluminum for next time. I’m thinking a purpose-built tool might hold up better than that old plastic…

Speaking of fragile materials, the first 1911 I owned used a lot of cheap metal injection molded (MIM) parts. MIM is perfectly acceptable for some applications; for others, I prefer steel.

One part that broke on that first pistol was the slide stop.

While I’m sure the engineers at Rock Island use better components in their designs, I ordered a carbon steel EGW slide stop from Thunder Mountain Custom to be sure.

I was also concerned about recoil from the full-power loads I planned to shoot. According to Danill at Armscor tech support, the pistol ships with a 20 lb recoil spring and 25 lb mainspring. Those seemed reasonably stiff*: I didn’t plan to replace them with heavier ones unless I had to.

*compared to a 1911 in .45 ACP, which normally has a 16 lb recoil spring and a 23 lb mainspring

However, some internet authorities also recommend a flat-bottomed firing pin stop to mitigate recoil.

I decided that the oversized version from EGW would also keep the extractor firmly in place, minimizing malfunctions.

As it turned out, the new part would increase extractor tension enough to require adjustment later.

By the way, it’s important when ordering 1911 parts to know whether your pistol is a Series 70 (like most “GI” clones) or a Series 80 design.

As always, Mike C. at Thunder Mountain had my order in the mail within minutes.

The new slide stop fit perfectly. I kept the old one as a spare.

Here you can see the main difference between the firing pin stop I ordered and the original: the new one (left) has a flat bottom with almost no radius.

I knew the new one would NOT drop right in–it’s intentionally made too big, so you can shape it to fit your particular pistol.

I carefully filed bits away until the new stop just barely fit into the slide, then used cold blue on the exposed metal.

I intended to replace the standard firing pin spring with a stronger one to prevent accidental primer strikes; however, the Rock Island original was even stronger than the upgraded one so I left it in.

The pistol was MUCH harder to rack with the new firing pin stop–I can see how that would “spread out” the recoil as opposed to letting the slide instantly slam back, unhindered.

I disassembled the frame and lightly buffed interior friction points (sides of the trigger bow, sides of the disconnector and sear, sides of the hammer, mating surfaces between disconnector and trigger bow, etc.) with green abrasive pads, but left the engagement surfaces between hammer and sear strictly alone.

You can quickly render a perfectly good pistol inoperative or worse, dangerous, by fiddling with those.

They say the same about sear springs, but after reading this guy’s article I’ve been able to safely adjust sear spring tension on three different 1911s. Skip down to the second page where it says “Sear Spring Prep” and follow his instructions. No tools required, other than a trigger pull gauge–and patience.

I ended up with about the same break (since I hadn’t touched the hammer and sear engagement surfaces), but now with a consistent 4 1/2 lb pull.

When using this technique I find it helpful to bend both the center (disconnector) and left (sear) spring leaves so that each just touches its respective surface when you place the spring in its retaining slot. Then I lightly polish the contact points on the leaves with green abrasive pads.

To get my 4 1/2 lb pull I adjusted tension on the center leaf to 1 1/2 lbs, then the total/left leaf to 3 lbs.

Although it’s not difficult to adjust a sear spring you can still screw it up, with potentially dire consequences. Best to make small adjustments and check them as you go.

While I had the pistol apart I also reduced the trigger pre-travel.

You do that by bending these little “ears” on the trigger bow outward, forcing the trigger to sit further back in the frame.

It’s easy to overdo this and “preload” the trigger/disconnector to the point where the pistol fails a function check (e.g., the hammer won’t cock/stay cocked).

To avoid that, I make sure the back of the trigger bow doesn’t protrude past these rails inside the frame.

If you overshoot, take it apart again and bend the ears part of the way back in.

Reassemble the pistol and check it until you’re happy with the results.

Of course, anytime you change ANYTHING on a 1911 you should perform a thorough function check. Then when you shoot it, load a single round first, then two, then three, before you trust your “adjusted” pistol with a full magazine.

Use

My plan was to carry this pistol on a velcro holster board enclosed in a chest pack. I’d been using belt holsters but coats and rain gear tend to restrict access. With the chest pack, no one knows it’s there and I can still get to it in a hurry.

In addition to spare magazines**, I can fit trail maps and other essentials into the pack. I attached a bear spray holster to the outside where I can grab it with my free hand.

**Note: I buy upgraded magazines for almost all of my firearms. While not a glamorous purchase, I’ve found that lower-tier magazines can cause more gremlins and heartache than they’re worth.

For hiking in bear country I decided to go with Buffalo Bore Dangerous Game 190 grain “mono-metal” (copper) rounds, and use my own reloads for practice/general purpose shooting.

Range testing

I used a laser bore sighter to check the sights before I left: they appeared to be dead on.

I shot the Buffalo Bore ammo at 10 yards, standing. The recoil was easily manageable: more of a “push” than an obnoxious snap back.

The slide to frame fit was solid, with no rattles, the trigger was good, and the pistol fit well in my hand. It’s a little nose heavy, if anything, but I think that helps mitigate recoil.

I had the odd failure to feed which told me the extractor was still a little too tight.

The sights needed to move about an inch up and to the right, but I decided to test my reloads before making any adjustments.

Reloading

I planned to use the same reloading setup as my other pistols, which meant I needed shell holders (Hornady #10, RCBS #27–and a Lee #19, which I already had), Hornady New Dimension dies, and a Lee Factory Crimp die.

Speaking of which, the 10mm auto, like most semiautomatic pistol rounds, headspaces off the case mouth so it’s important not to use a “roll crimp” (the Lee Factory Crimp die for this caliber applies a mild taper crimp).

Some reloaders avoid deburring the outside of 10mm cases to ensure they end up with squared-off case mouths for positive, consistent headspacing. I always do a light debur and chamfer and haven’t had any problem with headspacing, at least not according to my gauges.

BTW, I had to order a separate 10mm case gauge since my pistol checker doesn’t include 10mm.

In another nonstandard procedure, I run all my auto pistol brass through the trimmer station on my case prep machine. Since these cases tend to shrink with use they rarely engage the cutter, but it makes me feel better. I spot check for minimum length, too: that way I know the brass is within spec.

I bought another pistol powder metering assembly for my dispenser: I use a dedicated insert for every cartridge so I can just leave it set once I settle on a load. It lives in that big red Hornady box along with the dies.

As far as components go, I really like the Hornady XTP line so I ordered their 180 grain bullets. I stuck with my favorite handgun brass from Starline and decided to try Accurate #7 powder (per the Hornady manual) with my usual CCI large pistol primers.

For load development I started with Hornady’s max load of 12.0 grains of Accurate #7, then stepped it down .2 grains at a time until I had six test loads. I loaded five of each (12.0, 11.8, 11.6, 11.4, 11.2, 11.0) and shot them over a chronograph at 10 yards.

I shot seated, using a rest to minimize the effect of shooter error on the resulting groups.

11.8 grains showed the best accuracy. Average muzzle velocity over those five shots was 1260 fps with an extreme spread of 26.7 and a standard deviation of 10.2. Despite the small sample size, I’m comfortable declaring a winner.

Further Improvements

I’ve been known to replace everything but the slide and frame on an entry-level 1911, but even a pathological tinkerer couldn’t find much else to change on this pistol.

The very slight remaining trigger creep meant there was no need to upgrade the factory ignition parts, and the pistol’s accuracy was surprising–certainly good enough to keep me from running out and ordering a new barrel.

I backed off the extractor tension to fix my occasional failures to feed, and adjusted the rear sight a few clicks up and right.

When I first had the pistol apart I used a feeler gauge to check the slop between the hammer and frame and between the sear and frame (ideally it would only be a few thousandths). There wasn’t much more than that, but I knew a set of appropriately-sized Shively shims*** would help smooth out the trigger pull.

***Full disclosure: I use these shims in just about every gun I own. They’re an excellent upgrade, especially for the price. Lance is great on customer service: his website has tons of useful information and he’s quick to answer your specific questions via email.

I traditionally use a couple of leftover hammer shims to reduce the rattle in 1911 grip safeties, but the Rock Island fit was tight enough to make that unnecessary.

The sights worked well out of the box. However, I think a green front sight is easier to see than red, so I ordered some .060″ green fiber optic.

Just snip the old fiber optic in half (I used sprue clippers used by plastic modelers to get a clean cut) and remove it. Slide the new piece into the sight, leaving the end protruding slightly.

Heat that end until it mushrooms–I used a heat gun–then snip the other end off and heat it to secure the whole thing in place.

As I’d hoped, this entry-level 1911 is now behaving like a higher-priced champ. I just need to shoot a few hundred rounds through it to finish breaking it in…