Sunday GunDay: Suhl-Action .22 LR Rimfire with Indexed Barrel
This article was originally written by noted rimfire gunsmith Bill Myers. Sadly, Bill passed away in May 2010, but his legacy lives on. He pioneered many advancements in rimfire gunsmithing and Myers-built guns still win matches in benchrest competition.
Crafting competitive rimfire benchrest rifles is considered an art as much as a science. The smith must understand subtle, yet critical aspects of vibration control, barrel tuning, and rifle balance. In the United States, only a handful of gunsmiths consistently turn out rimfire BR rifles that consistently run at the front of the pack at major matches. Bill Myers was one of those master craftsmen. In this article Bill discussed the process of building a winning rimfire BR rig. He reveals some interesting secrets, including his procedures for testing bedding performance and his barrel indexing system. Bill’s methods obviously work, as the Suhl-actioned rifle featured here won a truckload of trophies in its very first match.
Building a Match-Winning Rimfire Benchrest Rig
by Bill Myers
In my opinion, a winning rimfire benchrest rifle is probably twice as difficult to build as a competitive centerfire rifle. The relatively slow .22 LR bullets stay in the barrel much longer than centerfire bullets. This means that vibration control is critical. Likewise bedding is critical. Bore finish and lapping are very important. The amount of bore taper or “choke” can have a huge effect on accuracy. Ignition is also very important and above all, rimfire BR rifles need a very stable stock that tracks perfectly. A rimfire that shoots great is a complete marriage of all components and of the shooter’s need to be aware of everything possible.
Click Photo to Zoom
The rifle featured in this article was built from scratch with attention to all the details that go into accuracy. The goal was to build a gun that could win from the get-go. This would be a “Spec Gun”, meaning a rifle that was personally tested and tuned by me for optimum performance before it went out to the customer.
The Suhl trigger is as good as it gets so no change was needed. It easily adjusts down to about 2 ounces.
Baer Stock in Bubinga Wood
There are many choices when you start to build a complete rifle. It has to shoot well and it has to catch ones eye, or it’s just another rifle on the line. I prefer wood stocks on rimfires for two reasons: they are very stable if the right wood is used and they have a certain traditional appeal to many shooters. I chose Bubinga wood for this particular gun because it is very stable and heavy, it has a very dense grain and a very pronounced figure with a natural red color. The Bubinga is a very forgiving wood to work with.
Gerry and Bruce Baer in Pennsylvania do all my stock blanks. I do all my own inletting and bedding. The blank weighed 4.5 pounds when it came off of Bruce Baer’s duplicator. This Bubinga wood is so hard that it did not need pillars, but I put them in anyway. I bed all my stocks with Loctite Steel Bed liquid and add filler to desired thickness. The final bedding is done with an aircraft tooling epoxy that does not deteriorate over time. The stock has an ebony butt plate and six (6) coats of automotive clear, polished to a “high buff” finish.
Suhl 150-1 Action
Accurized and BN-Nickel Plated
I used a new, unfired Suhl 150-1 action. As explained in the sidebar below, the Suhl 150 actions were originally crafted in East Germany for position rifles. They have a very fast lock-time and come with an outstanding trigger. However, they need some work when adapted to a modern BR gun. The action needed to be accurized and threaded. I have a special tool that I use to accurize actions. It uses two sets of spiders for dialing-in the bolt raceway. After the bolt raceway is running true, one can thread and true up all bearing surfaces so that everything is in perfect alignment with the action raceway bore.
BN-Nitride Plating on Action
I decided to plate the action and all bolt parts with Boron Nitride nickel plating. I bough the BN Electroless Nickel Kit from Caswell Plating and did the job myself. I started by bead-blasting the action so that it would end up with a “satin” finish. The plating material is then applied in a tank. The Boron Nitride goes directly into the plating solution, but you need to use a pump to keep the solution agitated so the BN distributes evenly.
Once the action is completely ready (the metal must be perfectly prepped, with no contaminants), the process goes easily and can be completed in about half an hour. The end result is a very slick, low-friction finish, that is .0002″ (two ten-thousandths) thick and hard as glass. The Boron Nitride makes everything very smooth. After the plating job, the action was noticeably slicker than before.
The cone breech (photo below) permits the barrel to be INDEXED (rotated around bore axis) to any position on the clockface. You then test various rotation settings to find the best accuracy. The system does work. Some barrels shoot best in a particular rotational setting. E.g. with index mark at 3 O’clock vs. 12 O’clock.
Fitting and Chambering the Barrel
As for a barrel, I had two good choices: one Shilen 1:16″-twist, 4-groove ratchet and one Benchmark 1:16″-twist, 3-groove. Both barrels were very accurate and at the end, I decided to leave the Shilen on the rifle because I wanted to put the Benchmark on another Suhl I’ve set aside for myself. I chambered the barrel for Eley flat nose EPS. We’ve found the gun also shoots the new Lapua X-ACT ammo very well.
The barrel finished at 25″ long and features a tuner by the Harrell brothers of Salem, Virginia. I use a flat 90° crown–it’s the most accurate and its gives a good seal against the tuner. I also use a 45°, 12-flute cutter that leaves no burr when cutting the crown. This chamfer protects the crown when cleaning the barrel. There is no sharp edge for the brush or jag to hit on the return stroke. The barrel was headspaced at .043″ and I use a tapered reamer ground by Dave Kiff of Pacific Tool & Gauge in Oregon. The chamber leade area is lightly polished to remove reamer burrs. The breech end of the barrel is machined with a 1/2″ ball end mill to produce what I call a “Myers cone breech.” Technically, it has a sloping radius as you can see, rather than a straight-sided cone. Finishing the breech in this fashion facilitates indexing the barrel, as the barrel can be rotated to any position (on the clockface), without requiring new extractor cuts.
When indexing a barrel, one rotates it to different clockface positions relative to the action. Imagine marking a barrel at TDC or 12 o’clock, and then rotating it so the mark is at 3 O’clock, 6 )’clock, 9 O’clock and so on. At each position one shoots groups to determine at which index setting best accuracy is achieved.* I know that barrel indexing is controversial. I don’t want to get into a lengthy debate other than to say that I believe that careful and thorough testing can reveal a “preferred” index position for a good barrel. With the barrel set in that particular position relative to the action I believe the barrel can yield optimal performance. I perform the indexing tests indoors at 50 yards. I use a rail-gun with floating action. The barrel is held in place with a clamping fixture similar to an Anschutz 2000-series action. Basically, two vertically-stacked metal blocks clamp around the barrel. I can index the barrel this way simply by unclamping the barrel blocks, rotating the barrel and then re-clamping the system. I have a special system so the action can stay in the same position, even as the barrel is rotated. It takes time and effort to get solid indexing results. Normally I shoot at least 400 rounds of ammo in 3-4 indexing sessions. Shooting a handful of groups is not enough. You may think you’ve identified the best index position, but you need to shoot many more rounds to verify that. Also, in a very good barrel, the effects of indexing may be subtle, so it will take many groups to confirm the optimal position. In my experience, really good “hummer” barrels do not benefit as much from indexing as an “average” barrel. |
Accuracy Testing with Both Barrels
I tested the rifle indoors at 50 yards at the Piney Hill Benchrest Club range. There was no finish on the stock, but it shot well in my one-piece rest with the Benchmark 16-twist, 3-groove barrel and no added weight on the tuner. I shot 30 rounds of Eley Match EPS Black Box (1064 fps) and had 25 Xs and five 10s on the IR 50/50 style target. Not too shabby for a new barrel with no special break-in.
When the Shilen barrel arrived, I installed it on the rifle. By this time the stock had been clear-coated and finished, and the action had been polished and plated. I shot the Shilen barrel outside since it was too hot in the building. The first target was a 250-19X with a new lot of Eley Match EPS Black Box (1054 fps). The gun shot well. My friend Tony Blosser asked to shoot the gun, and he drilled a 250-20X in a steady wind using the same Eley ammo. See target at right.
Barrel Tuning Using 2-Way Electronic Indicators Bedding and Vibration Control Another pattern I watch for is uneven vertical movement. For example, if the barrel vibrates .008″ up but only .002″ down, that tells me the bedding has issues. As noted above, I look for minimal vibration travel (after the tuner is fitted and optimized), and I also want that travel to be relatively equal both up and down. Good rimfire gunsmiths agree that proper bedding has an important influence on vibration control and tuning. By measuring actual barrel movement during firing, we can, to an extent, quantify how well the bedding is working. At a minimum, we can see if there’s a serious bedding problem. |
Trial by Fire — Shooting the Gun in Competition
After semi-gluing in the action, the rifle was shooting great. So, I decided to take it to the Maryland State Unlimited Championship to see if it was truly competitive — whether it could “run with the big dogs”. As it turns out, the Bubinga Suhl was more than just competitive. The rifle won three of the six cards and won the meters championship. In the photo below you can see all the trophies the gun won in its very first match. One of the other competitors in Maryland, dazzled (and perhaps a bit daunted) by the Bubinga Suhl’s stellar performance, told me: “Sell that gun Bill. Whatever you do, just get that darn rifle out of here.” Confident that this was a rifle capable of winning major matches, I packed up the rifle and shipped it to Dan Killough in Texas. Killough has shot some impressive scores with the gun.
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Suhl 150 rifles were manufactured in former East Germany (GDR) by the Haenel firearms factory in the town of Suhl. This region has a long history in arms production. In 1751, Sauer & Sohn founded the first German arms factory in Suhl. Following WWII, Suhl 150s were produced for Communist Bloc marksmen, including East German Olympic shooters. Prior to German unification, the East German national shooting arena was located at Suhl and hosted many top-level competitions including the 1986 ISSF World Championships.
Superb Rifles with Amazing Triggers
Suhl 150 Benchrest Conversions
Many of these rifles were left “as built” and used successfully in prone competition. Others were converted into benchrest and silhouette rifles, “parted out” for the actions and triggers. If you were able to grab one of those imports at a good price–consider yourself lucky.
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Today Suhl 150 rifles are very hard to find in North America. In 2006, a used Suhl 150, even without sights, might fetch $1200.00 or more. Then, in 2007 through early 2008, hundreds of Suhl match rifles were imported. This drove prices down, and those “in the know” snapped up complete Suhl 150s at prices ranging from $450 to $850 (see 2007 advert at right), depending on condition.
* Bill Myers actually created his own clamping rimfire action to facilitate barrel indexing. CLICK HERE for Myers Rimfire Action. To index the barrel, Myers simply loosened three clamping-bolts and rotated the barrel in the action. Because there is no thread to pull the barrel in or out, the headspace stays the same no matter how much the barrel is rotated. With a threaded action, you might have to use shims to test different rotational positions, or otherwise re-set the shoulder with each change.
Last week we ran a story on revered stock-maker 
