Home Forums Hunting & Shooting Long Range Hunting 7MM-300RCM ON A LONG ACTION

Looking to repace my 7mm Remington Magnum tube with a cartridge easier on barrels.Love the 7mm bore but want something with less powder capacity and the .532 case head.

I was wondering if anyone knows if dies are available for the 7mm-300rcm and who would i have to talk to about a reamer?

Thanks a bunch

7mm saum or wsm seems a lot easier, no?

The WSM is no easier on barrels than the 7mm rem mag(Ithink) but I will check to see if saum will feed as slick as the 7mm-300rcm.

7WSSM............

W

You may be better off just trading the 7RM for a short action 7WSM or similar. With just changing the tube, you'll have a long action with a short round. The beauty of the short mags is the short, lighter action and gun. The short round may not feed so well from a long action.

DF

The two cases are "Almost" identical, the case of the 338 RCM being even closer to that of the 7 SAUM.

AND Dirtfarmer might have a valid point also, but you could check most of that issue before tearing down the 7 Rem Mag barrel to some degree.

A cartridge that shares similar capacity is that of the Remington Short Mags of 6.5 and 350... I was thinking that by necking up the 6.5 Remington mag it would then give you the reduced capacity you are seeking and the longer body of the cartridge might soften any feeding issues you might have with the RCM's and SAUM's and WSM's.
This option would allow for some liberty concerning bullet seating if throated such in your long action that you wouldn't have with any of the others in a short action.

But..... Trading/Selling toward a 7mm SAUM makes a ton of sense. (and so does several other cartridges of .284" dia.)

I used a 700 LA that had been chambered for 7RM and turned it into a 300WSM without any issues. The head size and everything matches up between the regular and short mags.

I'd look at the 7WSM or the 7SAUM if I were you, should be an easy conversion and both are pleasant to shoot. You might gain some barrel life, depends on how hot you run them.

4 cases,...WSM, SAUM, 350 RM and RCM are all so close as to be identical as far as the conditions you are presenting SawDoc...72 to 76 gr H2O...take your pick...

The 7mm WSM and 7SAUM are factory calibers so I wouldn't bother with the other two...wildcatting costs more...just take your pick of the two factory offerings, to me that's a no brainer.

As far as "hard on barrels" go...ANY case/caliber that produces over 40KPSI and has a powder level of 60 gr and over is "hard on barrels"...barrels getting eaten is the price of performance. If you want something that's easier on barrels trade off to the 7-08...I have two, a pistol and a rifle and they both do their jobs very well.

Besides you should get at least 2000 rounds of hunting level accuracy out of a 7RM, which is a lifetime for a normal hunting rifle. I have that many through my cheap ol' Sav 7RM shooting everything from sage ratz to elk and it's still doing >3/4" with just about anything I feed it and bugholes with one particular Nosler 150 gr bullet.

It's nothing but a simple rebarrel whichever way you decide...find a cheap take-off barrel and DIY or have a 'smith install a factory barrel. Ain't no thang, Bro.

Basically a krap shoot as to which factory or wildcat case to pick, but going factory would be much cheaper overall and the results would be an excellent shooter.

If it were me I would just stick another 7RM tube on it and down load a bit...I load my 7RM from 7-08 velo to 7RM and a tad over. It's all good.

Go 7 saum or get a smaller bolt head and run a 284 if you want a bit less capacity. I like the non rebated rim design or the rcm's and have a 338 rcm that I really like but if I was doing a 7 short and wanted a little less powder than a 7 rem mag it would be a saum.

Bb

Campfire member Terry Berkhouse had a barrel, reamer and dies in the classifieds awhile back. I considered it but just couldn't swing it. Ya might consider pming him for some details.

Biggest problem with the 7mm Rem is it's short neck,
which is claimed to cause early throat erosion, and relates to erratic pressure spikes.

Same short neck length problem with the short mags ...
not necessary in a LA .

If you don't mind the belt, there's the 7x61 S&H ;
capacity is similar to the 7SAUM/280AI,
Venturi shoulder, IIRC Norma supplies brass.

7mm Wby has a longish neck, and doesn't have to be loaded to max.

Maybe look longer ... Mashburn ?

Hopefully, Somebody will chime in with the MSM neck dimensions etc.

MSM??? or...WSM at ~0.243 is shorter than the 0.271" 7RM neck...SAUM neck is ~0.311"...and neck length can change dramatically depending on trim length. The 7-08 and 284 have ~0.284" necks.

I know there is a whole lot of hoohaa going on for a long time about neck lengths...I think the "problems" are actually other things getting all mixed up together and the neck getting blamed. Hi-velo varminters seem to like long necks, but I have never read a scientifically set up test between similar cases, one with a long neck and one with a short one. I would be interesting.

I like to stick close to a one cal neck whenever I build a wildcat. Just something from way back that may or may not mean a thing...BUT...some of my larger cal wildcats hang around 70% cal diameter and seem to work OK.

I think the neck length subject should be considered if building a wildcat, but other than that just something more to arguing about and not much else.

Burlyboy has a very good point...the 284 is an excellent choice and should work OK with your mag bolt head. It runs about 64-65 gr H20. I've had several including a long throating, 28" bbl jobby, to seat the 175 gr Sierras out as far as practible and get better velo...it would run very close to my 26" 7RM but with ~10-15% less powder. Pressure played a big roll here. I could get low end 7RM velos but at higher pressures in the long throated 284, but then I could crank the pressures up in the 7RM and get past the 284 at a run.

I had an 7BR XP-100 rechambered to 284 way back, but it wouldn't shoot worth chit, the twist was all wrong for the added velo and the recoil could whip that shooter up and back so fast you had to wear a hard hat to keep from splitting your scalp. I pulled it out every time the subject of "my badazzz rifle kicks like a mule" came up. I fired one round to show what would happen if you didn't hang on...and I NEVER got any takers to try their hand. Hahahahahahahah The boys would drift quickly after the demonstration.

Choices, choices...always choices. What a neat game.

284win requires a 0.473 boltface (308 class). If neck length doesn't matter, then why is the 7mm SAUM cleaning everybody else's clock at the LR game?

The 7mm rem mag is not particularly hard on barrels. If you do manage to wear one out, which will be hard unless you shoot a LOT, then treat yourself with a new barrel.

Yes....the 284 has a .473 rim size, and a .0500" body size, but depending on the skill level or requirements of you or your 'smith, a .532" bolt face will work just as well...you just have to fiddle with the extractor a bit maybe...Were only talking about 0.030" per side difference. MANY bolt faces don't have ANY KIND of recess and work with a wide range of rimmed AND rimless cases...take a look at a Mauser...OR in the case of a Savage, just change the bolt head.

I have a Savage bolt I ground out to fit the Rigby case...it will handle Rigby cases, Belted mag cases AND .473" cases...I just had to fiddle the extractor detent recess a bit so it would slide deeper into the face and grab the smaller rim a bit more...checking this out and doing the work to answer the question of "what needs to be done to do certain things" is part and parcel of what I do when I'm futzing around with things no one seems interested in doing.

It's of absolute NO VALUE to smiths trying to make a living and well beyond the perview or interest of anyone but an experimenter.

I built a 50 cal Rigby on a Tang Ruger that was origninally a 30-06...I had to grind out the boltface recess out a bit and use a magnum extracter modified to fit the larger case, but all I have to do to go back to the .473 rim size cartridges is replace the extractor with a OEM .473 extractor and swap barrels...

Lots of things can be done outside the "normally understood methods of doing things"...doing the "odd things" is just not all that obvious, economically feasable or acceptable.

I don't think neck length has ANYTHING to do with the skills of the shooter or the accuracy of the rifle OR what particular cartridge might happen to be in the winners circle at any one time. That basically depends on nothing more than spin doctoring like ALL polititians do. That kind of logic is totally faulty but is used all the time.

At one time the 7RM was winning all the marbles in 1000yd matches...you can say the same thing about MANY different cartridges. That really doesn't prove much other than it was "King of the Hill" in ONE limited time interval.

If the 7SAUM is top dog now, it will only be there for a time before something else comes along...this is no flame or diss the the cartridge...it is a good cartridge as are the many that came before and the many that will come after.

If you have one and like it, just enjoy it.

Interesting bit of info there as per the bolt faces...

I've said many times I'm NOT an expert on gunsmithing, but I do things to gain knowledge...I would much rather build something and muck it up and LEARN from the mistakes than just keep building things by rote.

I've built model airplane engines to Jimmy 6-71's, worked on large constructions projects to backyard projects and building a rifle, as far as the metal work is concerned is relatively simple, basically drilling/reaming a hole in a tube, threading it and sticking into another threaded part. Wood work is another story...I start out to make a wood rifle stock and end up with a tooth pick and a pile of kindling.

The fact that skads of information is available at your finger tips, few people do their own work or even question the status quo, gunsmithing schools pretty much teach the same procedures and people are pressed to get to work making a living, pretty much leaves out what I did and how I learned to "play with guns".

CNC lathes and mills don't lend themselves to experimentation EXCEPT as adjunct to producing a saleable product, they COST TOO MUCH....futzing with boltfaces in NOT ecomonically viable unless you plan on selling them in large quantities and some bolts don't lend themselves to simple modifications.

In the scheme of things, most of the hot air on forums has little or no permanence or value anyway.

MSM == Mashburn Super Magnum

I see....my data for the 7mm Mashburn Super Magnum indicates a neck length of ~0.350", case length 2.625" - 2.635" and case volume of ~84 - 88 gr H20 depending on the source.

Basically in the same catagory as the 7mmRM, 7mm ICL Wapiti, Quakenbush and Dakota, and several other similar sized pre-7mmRM wildcats. Why would you pick a REALLy "strange" wildcat, in some cases, over the original 7mmRM?...this seems to be going the wrong way as far as I'm understanding the OP's original question.

I don't see any redazzz here as far as bragging rights go...HOW MANY out there HAVE a Wapiti or Quackenbush chambered 7mm? Lots of pro's and con's to ANY wildcat, but it's neat to have something NO ONE or very few has. Hahahahahah

FINALLY!!!

The voice of reason!