As promised (to a couple of members), here's an article I've been working for a while from my blog. It really should probably be in the gunsmithing section, but I figure more lever-gun laymen may see it here. One day there will be a part 2, but that's still a long way off. Enjoy.The purpose of this article is to give an entry-level guide to some of the (easier) alterations you can make to improve a lever action rifle’s inherent accuracy. In truth there’s virtually an endless list of improvements the tinkerer can make. Nonetheless the return on effort somewhat diminishes following the more significant modifications. I’ll therefore focus on these fundamental (and essentially simpler) improvements. Most of my information for this article comes from the rather famous, yet sadly out of print book “Accurizing The Factory Rifle – M. L. McPherson.” And to quote Paco Kelly’s Leverguns:
“Gaining accuracy in a leveraction rifle is really not much different than doing it in a bolt action. The principles are the same. There is no mystery, it is just that most folks take if for granted that 3 to 5 inches at 100 yards is normal and you have to live with it. That is utter nonsense….first of all on today’s market there is not one brand of lever action, one style, or one make that won’t generally shoot into less than 2 inches with the right ammo. Some few individual guns (lemons) may go into larger groups…but bolt actions have the same problems with the unusual stinker in a group.”
The Problem with BeddingAs the barrel and action heat and/or any timber warps, most factory lever action rifles exhibit a wandering point of impact (poi). I’ve had accurate lever action rifles which were profoundly accurate, but only for those opening cold-bore shots. After that, the poi rather dramatically moved as the rifle heated up, usually downward vertically. This is what is often referred to as “vertical stringing”, and is really common for levers.
- Typical full-power 50m group showing “vertical stringing”. From cold, the group starts tight, but inevitably wanders after repeated shots.
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I’ve had other lever guns that also seemed to cluster nicely, but then seemed to throw a “flyer”, often more laterally than vertically. I’ll label this “lateral stringing”. Both are symptomatic of different bedding issues.
- Extract from Accurizing The Factory Rifle – M. L. McPherson
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Vertical stringing usually stems from forend stresses. “Flyers” may well indicate buttstock-to-receiver bedding issues. Using your favourite load, a valuable test is to obtain a good sense of how your gun behaves (as the barrel and action heats). Then, completely remove your forend and carry out the same test to see how your groups change. This can be a little tricky, but is achievable by balancing the receiver on a front rest. With a bit of luck, your poi will be noticeably more stable (without the forend); then you know your issues are coming from the forend. If not, then it’s reasonable to presume your issues are more likely to reside in the buttstock.
Part 1: Forend BeddingTo quote M.L.McPherson “Obviously, any system that places wood (or almost any synthetic material) in direct contact with both the receiver and barrel offers the potential for the following things to induce stress between the forend and the barrel-receiver system: changes in barrel temperature, due to shooting or atmospheric temperature; variation in stock size and shape, due to changes in atmospheric humidity”
A lever action rifle leaves the factory with a tightly fitted forend to receiver and barrel. As a result, as the barrel heats, the barrel has a tendency to expand and move away from the timber, thus resulting in the aforementioned wandering poi. The wandering direction can seem odd, however remember that any barrel taper will impact poi characteristics. Furthermore, wood-to-metal contact with respect to the receiver and frontal forend capture are subject to any timber warpage over time, also possibly affecting any inherent stresses on the barrel. The basic premise of accurizing the forend is to relieve these stresses.
Firstly, we will remove a little material between the forend and the receiver. We will then replace this material with a gel-type epoxy bedding agent. BROWNELLS ACRAGLAS GEL® is the perfect product for this. The traditional, less viscous, BROWNELLS ACRAGLAS® can be problematic (when bedding the vertical surfaces). From personal experience, I strongly recommend using a gel-style bedding agent for the following step.
- Use a gel-type epoxy bedding agent
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Remove the magazine tube for the entirety of Part 1. Using a fine toothed file, carefully file away a small amount of material where it keys into the receiver. This will be replaced by our bedding agent, providing the perfect fit between the forend and receiver (and removing any problematic wood-to-metal contact). After making these reliefs and reassembling, the entire forend should be able to (ever so slightly) rock back and forth.
- Unrelieved
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- Relieved – just a very light sanding on the bearing surfaces. Notice I haven’t altered the upper flats as this does not make contact with the action – only the lower flat surfaces and a tiny amount on the vertical.
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McPherson takes this a step further, and actually suggests adding a layer of RTV silicone here (between the new glass and receiver), however the wider consensus is that the simple glass bed here will suffice.
Ensure that the keyed portion of the forend that enters into the front of the receiver is clean. If necessary, use alcohol or carburetor cleaner to clean any oil from the wood. Ensure any excess solvent has evaporated, possibly use a portable hair dryer to heat the wood and evaporate the remaining solvent.
Apply multiple coats of release agent under the barrel in front of the receiver and to the areas of the receiver face itself that might make contact with the forend. Apply quality masking tape around the perimeter of the receiver, and around the adjacent perimeter of the timber forend (to protect the finish). Dam the magazine feed hole in the receiver with modelling clay, mask over the top of this. Also dam the magazine channel in the forend (preventing any bedding agent from flowing into the magazine channel). As a precaution I also dammed the narrow upward pointed channels either side of the barrel on the receiver. Basically, as neatly as possible, mask any timber and metal that you don’t want bedding agent to bind to; the only exposed area without tape and/or release agent should be the timber that keys into the receiver.
- Forend ready for bedding
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- Feed tube plugged, we still need to mask and coat the action here with release agent
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Mix a small batch of gel-type bedding agent. Since this material will be visible on the finished rifle, add a dab of colorant to match the hue of the forend. Remember a little bit of colour goes a long way.
- Go easy on the colarant – a little bit goes a long way
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Apply the bedding agent to the keying portion of the forend (the relieved perimeter that you just cleaned). Be sure to get a sufficient coating to adequately cover the surfaces that key into the receiver. Reassemble the forend (excluding the magazine tube). Wipe away the excess gel that extrudes out with a damp cloth.
- More gel is better - we can always remove later
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- You want enough gel so it extrudes out like this
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- Excess gel can simply be wiped away
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Allow to dry for 24 hours with the magazine removed and barrel and receiver supported. Do not allow the rifle to rest on the forend while the epoxy hardens, the rifle should be right side up and horizontal during this process. Once the epoxy is set the forend should come apart fairly easily.
Upon disassembly, chip away any gel that has spread up onto the upper flats surround the magazine channel - this area is not a bearing surface and thus should be kept that way. Your forend should now be a perfect fit that should facilitate easy disassembly and reassembly. This is the foundation of the next (most crucial) step; RTV silicone bedding the barrel channel.
- Only the lower bearing surfaces should have the glass bed.
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Again to paraphrase McPherson: I can recommend laying a bead of silicone down the barrel channel. Assuming the forend is bedded at the receiver and at the forend attachment hanger (as described in the previous sub-sections), this RTV layer can aid in preventing resonation of vibrations between the forend and barrel. Further, it performs as a soft cushiony gasket which will not produce or allow significant stressing between the forend and the barrel as the barrel and action heat.. On two-piece stocked rifles (including tubular magazine models), black RTV (Room Temperature Vulcanizing) silicone is the magic elixir for bedding the forend to the barrel and receiver. DO NOT, I REPEAT DO NOT use a traditional acetic cure RTV silicone for this purpose. Acetic cure will rust through your barrel faster than a fat kid with a box of cupcakes. Instead look for electronics grade RTV, it’s usually acid free. Permatex make one called “ULTRA BLACK”; that’s the one I used with good success.
- Room Temperature Vulcanizing silicone
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Before the application of the RTV silicone be doubly certain to apply a good thick coating of release agent to the barrel and receiver — failure to do this will almost positively guarantee that you will not be able to separate the forend from the barreled-action without destroying one or the other! This product does exactly what the name implies — it vulcanizes, bonding with tremendous tenacity and strength.
It is important to ensure that the barrel channel clears the barrel along its entire length. With a dowel that closely matches your barrel profile sand away the barrel channel until there is sufficient clearance to slip a playing card between the forend and the barrel channel with the forend normally installed. The card should not bind at any point. I achieved this by buying some 25mm dowel that matched the diameter of the barrel at its thickest point next to the receiver. I carefully turned the dowel down using 80 grit paper (and a cordless drill!) to closely match my taper. I then glued 80 grit onto this piece of tapered dowel, creating a sanding tool that near-exactly matched my barrel channel profile. As specified above, I then sanded out the channel just enough to (after reassembly) slide a few pieces of paper under the barrel with no pinch points.
- The poor man’s lathe!
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- Keep sanding until barrel profile is matched
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- I attached sandpaper on using epoxy
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- Sanded barrel channel
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- Sufficient clearance to slip a playing card between the forend and the barrel channel with the forend normally installed
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Apply a good thick coating of release agent to the barrel, especially the underside where the silicone is sure to make contact. Mask the outside areas of the forend parallel to the (newly) sanded channel - the masking should be neat and precise as this area will obviously be visible. Liberally apply release agent to the front of the receiver where the silicone could possibly extrude.
Run a large pea-sized bead of silicone down both sides of the channel (where previously sanded), enough so that a bead silicone will extrude out either side out along the barrel upon reassembly.
- Better too much than too little here – we will trim away any excess silicone once green
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With the magazine tube still removed, reassemble the forend and tighten up the screws. Invert the rifle and support in the horizontal position and allow the RTV sufficient time to cure to a soft rubbery consistency, about six to twelve hours. At this time the RTV is still "green", it has not developed its full strength.
- A little extrusion of silicone is what we are aiming for
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Use a single-edge razor blade or an X-acto knife (or similar tool) to carefully trim away the RTV that has extruded from between the forend and the receiver. If you applied release agent properly, the RTV will not stick too tenaciously to the exposed wood or metal surfaces. You should not have any trouble cutting and peeling the extruded RTV away from the barrel and forend.
- For best results lay the blade at about a fifteen degree (15°) angle to the edge of the wood. The goal is to cut the RTV layer off flush at the wood side but deeper at the barrel side.
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- The RTV bedded channel after curing and trimming
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- Not perfect, but pretty good. Especially on older rifles imperfections are less noticeable.
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That concludes Part 1. At this point I suggest shooting some groups to get a clear idea of how your rifle groups. It may be sufficient to finish your alterations here (and skip Part 2 altogether). It really depends on the nature and to what degree you are chasing accuracy.
- Following the bedding procedure, here are 9 shots in a row WITHOUT pausing between targets. 21grs AR2207/H4198 under a 150gr (~1900fps). No more vertical stringing.
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- BTW the above work was carried out on JM era Marlin 30AS manufactured in 1996
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- 200m 12-shot group - for a 30/30 lever, a bit over 4" is pretty outstanding for such a long string of shots.
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