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35-284 or 416-284...ANYONE do one?

9312 Views 49 Replies 7 Participants Last post by  NFG
I'm back to wanting to "stoke-up" my Marlin 336 356 Win and do a 416 cal barrel. As far as I know the 336 and 1895 have the same barrel OD, threads, etc at the chamber, so I think it's doable. I'm looking at the 284, 444, 45-70, 450 Marlin and 350 RM cases to use as a basis.

I've been warned off the 284 case, but the reasons weren't sound...considering the size of the 45-70 and belted mag cases already in use.

I've been building my own wildcats for a very long time, have a lathe/mill etc., so I need input from someone who has done one or from a gunsmith with specific knowledge of the 336/1895. I will probably need to swap bolts and lifters and do some fitting I'm guessing.

Initially I want to do a 350 RM rechamber(35-450 M, 35-458 American, 35-284 etc) on my 356 Win, keeping the pressures within the limits of the rifle NOT the case...~40-42KPSI. I can reach 2.62" OAL without any problems.

I have Load from a Disk and can design the case with minimum taper to help with bolt thrust.

I also want to do a 416 using the same cases.

I've also talked with a couple of leversmiths, but as they are in the buisness of selling their products AND knowledge I didn't get too much specific information.

Any help or thoughts will be appreciated.

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I like your thinking but you have to remember the Marlin will not take the pessure of a Mauser.
You are also limited by how long the action is I think going with a 45/70 case necked down or a .444 is the best way to go but you have to keep the ovl and pressure to work with the Marlin. I have a .375 baised off a 45/70 in my mind for some time now.
If you want to work with the .284 or .308 cases at normal op pressure I would say your best bet is to find a older BLR to work with.
I understand....The Marlin is rated at at least 43KPSI for the 450 M and supposedly 52KCUP for the 356/375 Win standard loads. Whatever case I decide on I will load for the pressure limits of the MARLIN RIFLE, not the SAAMI specs of the case/caliber.

My Marlin will handle 2.62" OAL right now and I will be sending it to Mic Mc or Nonneman to have a "long action" done to it so it will handle up to 2.68" or so. I just have to seat the bullet to that length spec and load it mindfully.

If you take a look at just about ANY reloading manual, they list a range of pressures for each cartridge. The 350 RM for a 250 gr bullet has a low end starting at ~37KCUP and going up to ~53KCUP...that is supposedly within the pressure limits of the Marlin...the 336 was chambered for the 375 Win and 356 Win at one time.

I've had mine apart to do the barrel rebore and other mods and measured and calculated all the "stuff" back about 3 years ago, so I'm confident of what I WILL do fairly soon, and as I said, I've been reloading, doing wildcats and building rifles for a very long time, but I STILL APPRECIATE any observations others matter how good we think we are...we still can overlook something very obvious to someone else.

I have a bit of a problem with understanding WHY the 0.506" OD of the 45-70 is OK but not the 0.500" OD of the 284 case. There could be a slight problem with the 0.513" OD of a belted mag case with the belt turned off...but the 0.007" difference between the 45-70's OD and the nonbelted mag case shouldn't cause much redazzz.

I'm not even sure the rebated rim would cause a problem as the Marlin bolt face is already set for a 0.473" case head, but that has been brought up also.

The 375/45-70 has been done and it was my thought also when I was thinking of doing a 375 Win instead of the 356 Win rebore. A fairly simple straight forward rechamber job. I want to stay away from the large rim of the 45-70, but that could be turned into a rimless case pretty easily, but is a lot of trouble when other cases are readily available.

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The rebated rim of the 284 case my be the reason it might not work as well. It may cause feeding issues out of the mag tube, as in not being to hold the next round back in the tube. The case dia. is fine.

I have a 375 JCC wildcat based on the 338 RCM case in the works. I have it chambered in a bolt gun now & the marlin 450 xlr is going to Nonnemans soon I hope. The rim dia. is the same as the 450 but the case just carries forward at .532 with out the belt so it is fatter over all than the 450 case. There is alot more info here;,59513.0.html

Thank you very much, John...I have checked out the 358 JDJ and the 375 JDJ several times in the past...the "problem" with the case OAL can be mitigated somewhat by lengthening the action, trimming the case slightly and just seating the bullet to the length that will work through it...nothing all that hard to do....this is just a wildcatted wildcat.

AND...I checked out the RCM case as soon as I saw it as a basis for a wildcat...but the case OD put me off, the square threaded chamber walls were getting a little bit thin using anything over 0.0506 45-70 case OD..

I thought all the 348 case coversions needed extensive receiver/barrel mods, but I've since read it was just a rechamber, but I HAVEN'T read whether it was a rechamber to a "V" threaded receiver or a SQUARE threaded receiver, for certain...Widipedia just states it's a rechamber but not WHICH receiver. I am still checking that out.

If anyone knows FOR CERTAIN just which receiver, SQUARE OR THREADED, are used for the 45/50 ALASKAN conversion and what, if any, other mods were required I would sure appreciat the information.

I know of one 450M rechamber to 450 Yukon, a shortened RUM case that worked great.

Your XLR has "V" threads so the RCM conversion should be a shoe in.

I'm talking to Regan right now and will be sure to ask him if the square threaded receiver will work with the RCM case...if so I will be ordering a reamer from PT&G very soon...I already have a "35 RCM" designed and several loads worked up in Load from a Disk for that case.

Keep us posted about your progress.

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I understand about the square vs. V threaded receivers And as you said the 450MXLR is V threads. I was going to make a 358 JCC until I found out about the 338 ME. I thought the 358 was just too close cal wise & moved up to 375 JCC instead. Over all I'm glad I went 375 over 358.

What changes did you make, if any, to the RCM case for your 35 RCM cartridge? What type of performance numbers did you come up with. That should be a very good cal. I would like to know more. I assume 43-45kpsi. working pressure in the marlin?

The 375 JDJ could be made to work I guess but by the time you shorten everything up to fit, even at say 2.65 COAL, it will loose some performance & the load data will be incorrect also. Why bother is what I decided.

Please keep us posted here if you would also. Nice talking with you.
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By the way, if you are using a 356ER action for the conversion I believe that receiver has V threads also.

You're going to an awful lot of trouble to make something that is a MARGINAL improvement over the .356 at best. Why don't you just neck up the .356 to .375. Or better yet, buy a 45-70.
Most cartridges are only MARGINALY better than another one. All with 150gr bullets; 30-30=2300fps, 30-40 Krag=2450fps, 300 Sav=2600fps, 307 win=2600fps, 308 win=2800fps, 30-06=2950fps, 300WSM-300 win mag=3200fps, 300 Weatherby=3350fps, 300 RUM=3450fps.

The biggest jump between them is 200fps. give or take say 50fps. Besides................IT's FUN!!!!!!!!!!!! ;) ;D

Wellllll.....I HAVE a 45-120 I can shoot 45-70's in for "plinking", 458 American that I can shoot 45-70 and 45-90 rounds in, 375 H&H, 50 cal...etc, etc, etc. I've been wildcatting 50 odd's in my blood and under my fingernails. I don't NEED another rifle yet I have 4 at different levels of process...and this one might make it 5...just this year alone.

As to the marginality, that is what wildcatting is all about. It is the extra energy that is the quest. Bullet energy increases at the square of the velocity so an extra 100 fs can give you many hundreds of pounds more striking energy...the 356 is a very good cartridge with a 220 gr Speer running 2250 - 2300 fs with ~1500 ftlb energy at 200 yds, jumping up to ~2400 fs and you gain ~400 ftlbs of muzzle energy and about 160 ftlbs more at 200 yds...or having something special that no one else has. With the big bores a gain of 100 fs with a 500 gr bullet can mean 500 ftlb more whack.

But you're right, LVRFAN, the difference between a 356 and a 284 really doesn't justify the cost, but the difference between the 356 and the 350 RM is ~16 gr H2O. That would give me about 3200ftlbs ME with a 250 gr bullet at ~2400 fs against ~2500ftlbs ME with the 220 gr at ~2300fs...THERE'S where the value goes way PAST marginality in a NY second.

Wish I DID have the ER action, but No...I've had this one apart to do the 356 Win conversion...It IS a square threaded receiver. Sent the barrel to Jes Rebore to do it. At the time the 356 Win was the better choice as I had other ideas for down the road. Now it is down the road and I'm starting to work on it again.

All I did with my design was neck up the 338 RCM to 35 RCM without any other changes...that's only a 0.020" big deal.

I thought the same about the 375JDJ, but now that I understand some leversmiths can lengthen the action to 2.85" it has more appeal, except now with the WSM and RSM cases, even a belted magnum case with the belt turned off is a step backwards for a V threaded receiver...the WSM case at ~80-85 gr of H2O would be the one I would/have done if I had a V threaded receiver...but probably a 416 cal...some very nice heavy, high BC bullets are available for the 416.

A 375 WSM with a slightly blown out shoulder would have ~84 gr H2O...2300fs with a 300 gr RN at 2.85" COL easy enough with a 24" bbl. That's running neck and neck with a 376 Steyr. Not too shabby.

Yes, ~43KPSI would be my max with a 450 M, RCM, WSM or similar sized case.

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I would have tryed the 375 WSM but i was afraid of the rebated rim & larger dia. of the case. I also wanted something that was easy peasy to form & chamber with out much modification to the action ect. My 375 JCC is also a simple neck-up job with no other changes. One pass through the die & your done-no trimming required. This is my first wild cat so "simple" was a good thing. ;D

The 450 Yukon, 45 cal WSM an online search - all the information is available at Beartooth... is a simple rechamber in a 450 Marlin, no problem with the rim, and cases are easily made. I see no problem with doing a 375 WSM.

Wildcatting requires lots of decisions no matter what. :eek:

But as long as you are happy with your 375 JCC, that's all that matters...the rest is just smoke and mirrors. ;D

I think the rebated rim "stuff" is overblown or no one has actually tried it, at least it is with the 284 based wildcats I've built for Rem's and Ruger's. Sometime in the next few days I make up a few 284 dummies and try it for myself...that way I will KNOW for certain. This is a work in progress just started, so I don't have all the answers yet. It boils down to how much "extra work and parts" it would require, and how much "mucking about" it takes to get there...I already know it requires some mill work on the ejection and loading ports.

At some point economy dictates what actually the fact when I started this "imagin-airy" project several years ago I could get parts from Marlin, now that has changed, so I don't know just how far I will get.

I keep hoping to get good feed back from others that have done conversions, but so far either there aren't that many, those that had don't go online or they are just keeping mum.

Enjoy your shooter, John.

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I made up some 284 dummy's today...good news, the rim didn't cause any ruckus, bad news the case is too fat in front...there is some inside the frame dimensional differences at the front between the 336 and the 1895 to accomodate the larger OD cases of the big bore. The same with the WSM case.

I also ran some LD data for the 375-284 case which ends up about 70 gr H20 or about 14 gr over the 356 so the gain is the ability to use a 300 gr, 375 OD bullet at the same velocity as in the 356 if the action could be lengthened to handle ~2.85" would be worth the effort for that alone. I don't see a lot of interest in wildcatting for the smaller calibers anyway. I will definitely keep my eyes open for a "cheap" bigbore tho'...I still want my 416 something, something levergun.

The big brown truck delivered my 8mm bullets and 25-06 brass for my new 25-06 and 8mm Mauser projects, so the Marlin gets tabled's very close to bang flop dead, but I will strip down the Marlin sometime this year and see just what milling is required to handle the fatter cases...maybe it will get a reprieve again.

Wouldn't it be nice is RemMarlington would do a 375 cal big bore RCM/WSM, long action with the mag tube dropped down about 0.050-0.075" where it belongs. ;D :D 8)

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It is my understanding that the lever itself is milled thinner in one spot for the larger cases & rims to slide by. As for the mag tube being lowered in the frame..........Hell ya. I don't see why they don't "just do it". How hard could it be?

A 375 RCM/WSM with a 250gr gummy tip would be just great. Power & range in one small package that isn't going to kick you into next week ;D That was my whole reason for the 375 JCC. A true hunting cartridge that could be used for big & small with 250yd. range in a user friendly platform. I need to get it done as soon as taxes get back.

As for the rebated rim being a problem, you are probably right. I'm sure it would work just fine.

I've been crawling all over the net, parts pictures and places etc, asking questions and so specific or direct information forthcoming. Gun Parts has many parts but I can't tell from drawings just where and what...the receivers are supposed to be exactly the same except for the ejection port differences.

Wish I had levers from both to measure or see the shape/milling. It looked like the case was wedging against the lever but not by very much and it was hanging about 3/8" from the shoulder at about 3/4 stroke, so it won't take much to clear it. Sure would be nice if that was all that is needed.

I also want to go with a 26" bbl, just like the Cowboy...a 416/284, 350 gr bullet at 2000-2100fs for ~3250ftlbs ME, 2600ftlbs at 100 yds, 2000ftlbs at 200...that's plenty all right for sure. The 450 Marlin is ahead at the muzzle, neck and neck at 100, but starts fading fast past that mark. Your 375 should do even better with the right pointy bullet as a two shooter.

I'm must be part masochist...the whack from a big bore just makes me smile, shake and tremble all over...and breath heavy at the same time. Hahahahahahahasick

I'll have the 8mm and 25-06 going in couple of days, I've prepped the cases already and started load workup on the 25...this Savage Axis doesn't like the same load as my Rem Sendero liked already and the trigger is 6-7 lbs AFTER I played with the springs and polished the sear a bit. Looks like I be buying a new trigger for it.

I have about 3 weeks yet before the new barrels for my other two projects arrive, so I might strip down the Marlin and really get up close and personnal with it again...I really need to measure the threads myself to be sure. The snow is clearing off quickly so I can get into my shop and start making chips again.

Midway was out of 375 barrels last time I checked but they did have 416 barrels...maybe my choice is being made for me. will be fun to actually get the project in the starting blocks if there actually is a way to do it.

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These are 45-70 levers. see the milled out area towards the end.,70746.0.html

The first 3 are 336 levers & the last one is a 45-70 lever with the milled out area.,61441.0.html.

Hope this helps

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Far out, Man....thank you very much, again...I've been looking but not seeing all this time. ;D

I really like those big loop levers. One is on the "buy" list along with the leather loop cover...if I quit spending my not so very available loose cash on food, gas and other non-essentials. ???

I'm gonna go blind staring at the monitor chasing parts and info before this is all over.

Snow and cold came back again...normal late winter weather...sunny for two-three days, just enough to get me started on some project, then Ol' man winter starts laughing again.

I keep going back to the 375 cal 284 cased cartridge although a beltless mag would have slightly more case capasity and a shorter length...other than having to turn off the belt it might be a better fit case AND OAL length. Wouldn't take much to do t5 cases...this isn't a varminter where I go through 500 rounds in a weekend. ::)

This is old-time wildcatting...having to re-invent and discomboob-youlate everything. Hahahahahah

If I was smart and flush I would do it the easy way...just buy a Win 71 45-90, send it off to a real leversmith and have him do a 375 AND 416 barrel...Naw, where's the fun in that. :D

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You are welcome. I asked a lot of questions doing my 375 project so i'm glad to give a little back when I can.

You keep going back to turning off the belt on a magnum case. I don't see why you would do that? The belt doesn't cause any problems that I can see? You can head space off the belt or off the shoulder. Should feed just fine out of the tube mag.

I like the big loop lever also but not as big as the WWG/Marlin lever. They are just too much of a good thing. I like the DCR loop & Mule Man loops better. Most of the big loops have the milled out type lever so that they fit 336 & 45-70 actions with one part.

You are welcome to use my reamer for the 375 JCC if you wanted to try that out. Hell you might get your rifle done before I do ;D ;D

I'm trying to arrive at a case with maximum case volume and minimum case OD. While the belt per se isn't a problem in feeding, the metal "thinness" around the chamber is the issue. Once the case OD starts getting over 0.500" then the thickness/thinness of the barrel metal under the square thread minor dia starts becomming the issue.

Turning the 0.532" belt down to case OD just in front of the belt equals 0.513" and the distance from a standard belted mag cartridge base to the end of the belt is 0.220, a 450 M is 0.252" and the solid brass section for both is 0.244"...the tenon length is ~0.65" long so the thinnest section of metal in the chamber is ~0.406" long. You can go nutz trying to work through the "area under the curve" or just take a cross section area somewhere along that length and calculate how much pressure that representative section will handle before making life as you know it come to an end.

I'm just crunching numbers, asking question, making some observations and HOPING the questions and answers will stir up some "controversies" which will also give me more information to use to arrive at a safe conclusion...hopefully.

All this monkey motion could be moot anyway...the belt is supported by solid brass which by itself will handle a good 65KPSI and at a point outside the pressure issue at the pressures I will be running...there is only about 5 gr H2O difference in using a "belted OR beltless" 350RM/other belted mag case at 75gr H2O and the 284 W case at 70gr H2O,, using identical lengths and case design dimensions, which also adds adds the cost of a reamer and only gives about 50fs more velocity...not worth all the extra work for certain, but could only be understood by doing the "thought experiment".

Yeah, the only way to a wildcat is lots of questions and mucking about with numbers, blood, sweat and tears...thats the joy of wildcatting..."the other side of the story", is all the extra good stuff you learn that others miss out on.

I appreciate the offer of the reamer, but with a square threaded receiver, the OD of the RCM case puts it way beyond my comfort zone. Using that case in a "square" receiver leaves only about 0.95" of metal and crunching that number gives 0.7 safety margin at 45KPSI...If I could have gotten away with the larger case I would have done my 416 WSM way long time ago...I've been messing around with this since 2008.

The good part is I can rent a 375/284 reamer for $55 bucks, the dies are available from CH4D, the bad part is it took 9 months to get the last set of wildcat dies from CH4D, so the total cost of the rebarrel is less than $250, and I won't have to mess about with the boltface, extractor, ejector, carrier, only do a little milling on the lever or buy a big loop. I will have to send it out to DRC or Nonneman if I want the full 2.75"-2.85" case length treatment tho', like he does for the 45-90 case...that might get a little pricey.

A 375 cal, 265gr hard cast FN bullet at 2.65" OAL and ~2300fs isn't a 375 H&H, but it will handle just about anything I care to eat. ;D

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How hard is it to open up the 7mm neck on the 284 case to 375 ? That seems like a lot. I would use the 284 case over the belted case for sure if it means turning off the belt.......that's just me ;)

I will say you do learn alot making a wild cat, I did for sure & i'm not done yet.

Good luck & keep us posted

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