The Official Word on Rechambering the Marlin 336 Rifle from .35 Remington to .356 or .358 Winchester

By Barr H. Soltis

It was Saturday, January 17, 2009, when I made my usual trip to the Sweede Road Rod and Gun Club located in Pigeontown, PA for a little range work. The usual crowd was shuffling in and setting up their stations for a little target practice. The club boasts a covered outdoor range with two pistol stations for 25 yard shooting and 10 stations with backstops for 50, 100 and 200 yard rifle shooting.

Just a few days before we had our first membership meeting for 2009, we voted in about 10 new members. They included a man in his late 30's who brought his 10-year old son with him to the range on this cold and snowy Saturday morning. Although I did not know his name at the time, I later learned from local news reports that his name is Elwood. I found this out while I was at home washing the dried blood from my hands.

Elwood appeared to be a nice fellow and it was nice to see his son sitting beside him on the bench. My chance to become better acquainted with Elwood and his son was preempted when the range officer called the range “HOT.” Elwood was shooting a Marlin 336 lever action rifle that I recognized as a .35 Remington model. Most of us were shooting bolt action rifles chambered in .223 Remington, 6.5x55 Swedish Mauser and .308 Winchester.

I glanced over at Elwood and noticed that he was having some type of mechanical problem with his rifle. It seemed that the cases were not ejecting with the usual ease of a 336. Moments later it came, the explosion, followed by blood curdling screams. As the action exploded into fragments, Elwood’s trigger finger was shredded. Pieces of the steel receiver ripped into the right side of the boy’s face, but luckily none was fatal and the protective glasses that he wore protected his eyes from the flying debris. I hope that the plastic surgeon will be able to restore his face to original condition after the burns heal.

All of this could have been prevented, but Elwood thought the super cool bargain he had picked up at a pawn shop was something he could not pass up. It was a Marlin 336 that had been rechambered to .358 Winchester. Unfortunately for Elwood, at the very moment that the explosion occurred, he lost more than his finger; he lost his career as a court reporter as well. You just cannot type fast enough with only seven fingers and two thumbs. I think that Elwood will be singing the blues for a long time.

While the above is a fictional story, I wrote it to illustrate my point.

Many hunters who own the Marlin 336 chambered in .35 Remington are not satisfied with the anemic factory loaded cartridges that are offered by the major ammunition manufacturers. These people believe that the .35 Remington, which was introduced in 1906, could be much more and I agree. The problem is that not all rifle actions can safely withstand the pressures that the Marlin action can tolerate and this is why you see load data that skirt the maximum energy levels that otherwise would be safe to use in the Marlin 336.

I believe that maximizing the potential of your rifle or hand gun cartridge is an acceptable practice, but it must be done in an intelligent manner and within limits. Unfortunately, there are those who want to increase the power of their firearms on the cheap and tempt fate. For them, the answer is to ream the chamber of a .35 Remington to accommodate either the .356 (rimmed) or .358 Winchester (rimless) cartridges. I submit to you that this is a potentially dangerous accident waiting to happen.

There may be times when you can make a silk purse out of a pig’s ear, but rechambering a .35 Remington to either of these calibers is not one of them. Over the years, I have found a few articles on the internet and forum chat with claims that you can up the ante simply by running a reamer through the chamber of a Marlin .35 Remington and viola, you have your new magic dragon slayer.

I have to admit that the proposition is intriguing. In one article, the author discusses how a gunsmith came across a broken Marlin .35 caliber rifle, restored it to its original condition and then rechambered it to .358 Winchester. Reportedly, the rifle and conversion combined cost less than if you were to buy a new Marlin Guide Gun, but in the long run, is it worth it? I think not.

(The .358 Win. is factory loaded with hard point semi-spitzer bullets, which are strictly forbidden for use in the tubular magazines of Marlin 336 rifles! If you insist on blowing yourself up, at least avoid a magazine chain reaction explosion; go the .356 Winchester route, as it uses flat point bullets designed for tubular magazine rifles. -Ed.)

Some of you may disagree with me and that is fine. However, I believe that there is a time in our lives that we have to stop believing in Santa Clauss, the Easter Bunny and the Tooth Fairy. It is time to come to grips with the fact that rechambering a .35 Rem. Marlin lever gun to .358 Win. is simply impractical.

I am happy to announce that Dave Camera of the Marlin Firearms Company responded to my inquiry about this subject. This is Marlin’s official statement: “It is Marlin’s policy that any such conversions are not safe and should never be done. Marlin, as part of the R & D process, extensively tests any and all chamberings we offer in any given model to protect our customers. Without said testing, we will not guess as to the potential outcome. Any conversion of this nature should be considered hazardous to all involved, will void all warrantee claims and be done at the liability of the person doing the conversion.” I believe that this statement should make any further debate a moot issue.

In a previous article, "CPR For the .35 Remington," I briefly discussed the Marlin rifle, but more especially the cartridges that are currently available and my conclusions are as clear today as they were then. I submit to you that the .35 Remington is a wonderful deer and black bear cartridge that can humanly harvest deer, black bear, hogs and even larger animals at appropriate ranges with both factory and hand-loaded ammunition. I also suggested that if you felt that standard cartridges were not sufficient, you should try Buffalo Bore ammunition.

During the past few years, I have I fired Buffalo Bore loads from my Marlin 336 SC, which was manufactured in 1958. The head spacing was fine and none of the cases or primers exhibited any signs that would indicate excessive pressure. If you really want more power from your Marlin .35, try Buffalo Bore ammunition before you spend your hard earned money and expose yourself and those around you to the potential dangers of a rechambered Marlin.

Tim Sundles (the owner of Buffalo Bore Ammunition Company) provided me with the following information: "Assuming a muzzle velocity of 2250 fps with a Speer 220 grain bullet, this load generates muzzle energy of 2475 ft. lbs.; at 100 yards, energy of 1936 ft. lbs.; at 200 yards, energy of 1518 foot pounds."

(If those numbers are achieved from the 20" barrel of a Marlin .336, this is a VERY hot load, likely in excess of the SAAMI MAP for the .35 Rem., which is 35,000 cup. The highest velocity, maximum pressure reload for that bullet listed in the Speer #14 Reloading Manual delivers a MV of 1901 fps from a 20" Marlin 336 barrel. For comparison, a maximum load for the .356 Winchester [MAP 52,000 cup!] typically drives that bullet to a MV of about 2300 fps from a 20" barrel. Heed the author's warning at the end of this article. -Ed.)

Based on these numbers, Hornady’s HITS calculator (Hornady Index of Terminal Standards) scores a whopping 1213. Hornady uses a numbering system where you can place your calculated score to determine its optimal use at 100 yards. In this instance, a score of 1213 falls about dead center in the 901 – 1500 category for large game, which they define as 300 to 2,000 lbs. This is what I would use if I were on a paid pig hunt, was hunting for black bear where the potential for large bruins existed, or if I were going to shoot an elk at short to medium ranges.

My calculations indicate that the maximum point blank range (MPBR) for this cartridge when sighted in at 100 yards is a good large game cartridge out to about 155 yards, where most medium to large game is killed. Sighting in at 3 inches high at 100 yards should increase your MPBR out to about 200 yards. At this distance, this bullet retains about 1456 foot pounds of energy.

Buffalo Bore’s .35 Remington ammunition is loaded with a 220 grain Speer Hot Core flat nose bullet with a sectional density of .245, enough for at least a 450 pound animal. I think that it is safe to say that this bullet will not be easily deflected by twigs and leaves as pointed bullets would and will strike its target with bone crushing penetration. Let us not forget that this bullet starts with a large pre-impact cross-sectional area of .1007. At 2250 fps velocities, I believe that it is reasonable to expect this bullet will both penetrate and expand to lethal proportions.

Buffalo Bore enjoys a solid reputation in the ammunition community by offering a quality product for both rifles and handguns. I must say that this ammunition is not for the faint of heart, as the recoil is much more pronounced than your average factory loaded cartridges. However, if you want your firearm to perform at maximum levels, you have to expect a little compromise and, trust me, Newton’s third law of motion clearly applies. Puff, your days are numbered!

Please note that Buffalo Bore Heavy .35 Remington ammunition is safe for use only in mechanically sound Marlin lever actions, Thompson/Contender Encores and strong bolt action rifles (Remington Model 600 and the like).

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Copyright 2009, 2013 by Barr H. Soltis and/or All rights reserved.