Lloyd Smale
Member
Ive got 7mm ultra barrel that im going to screw on to my bdl in 7 rem mag. Will everything else work like the bolt face floor plate ect?
coverting a 7rem mag to 7 ultra?
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hardluk1
member
May not work at all. Base on the ultra is around 18th's larger and long enough to need a magnum action for the ultra where the 7rem mag will work in a 30-06 sized action. Also your mag well area may be to short for the ultra's length plus the cost for any amount a smithing will set the cost high enough you may just want to look at a new rifle. The ultra ain't a fix for anything that the 7mm rem mag can't do. Wicki the 2 rounds and make notes and you will see the difference . Why do you want to change. Hand load the 7mm rem mag and you can step it up to a higher level .
NCsmitty
Member
As mentioned, COAL will be the problem, unless you want to have a single shot or seat the bullets ultra deep and sacrifice powder space. The magazine remains the problem.
The 7mm Dakota may be the answer and is basically a short version of the RUM, and works through standard length actions.
It might be possible to set the RUM barrel back and rechamber for the Dakota round, but in reality, the 7MM Remag is a balanced round and will certainly do the job in the normal ranges encountered that the average shooter can actually hit their target.
With the 7mm RUM, why burn 25%+ more powder, for less than 10% performance gain, when compared to the 7MM Remag? Few people can actually take advantage of the difference.
NCsmitty
The 7mm Dakota may be the answer and is basically a short version of the RUM, and works through standard length actions.
It might be possible to set the RUM barrel back and rechamber for the Dakota round, but in reality, the 7MM Remag is a balanced round and will certainly do the job in the normal ranges encountered that the average shooter can actually hit their target.
With the 7mm RUM, why burn 25%+ more powder, for less than 10% performance gain, when compared to the 7MM Remag? Few people can actually take advantage of the difference.
NCsmitty
hardluk1
member
I rebarreled mine along with someother work and changeing from the stock 24" barrel to a 28" kreiger barrel was good for an extra 115fps average. I shoot the old hornady HM139gr sst and average 3410fps. Thats what the ultra's 140gr advertize's. Oh It way easier on my shoulder and rear pocket too.
Yeah, id probably stay with the normal 7mm. The ultra while nice, has to be handloaded and have a long tube to really get much more then any of the other fast 7mms. My SPS has a .375 length magazine it would handle the ultra. I dont remember if my old 7mm BDL had the longer mag or if it was 06 length.
MachIVshooter
Member
If your rifle is a Remington 700, it's doable; They only have two action lengths, and the LA is used for everything from 6mm Rem to .375 Ultra.
Feasibility is another issue, though; The 7mm RUM is way overbore, and performance really isn't much better than what you have. The 7mm STW teeters on maximum for the .284 bore size. The RUM will burn 50% more powder than you 7mm RM for a max gain of 300 FPS.
Feasibility is another issue, though; The 7mm RUM is way overbore, and performance really isn't much better than what you have. The 7mm STW teeters on maximum for the .284 bore size. The RUM will burn 50% more powder than you 7mm RM for a max gain of 300 FPS.
Lloyd Smale
Member
I knew they only had two action lenghts but was conserned about the mag box and floor plate. As to why? I have 3 7mm rem mags right now. Two 700s and one hawkeye. Dont really need 3 and found this barrel that was a new take off for 50 bucks and figured it would be something new to fool with. Thing is too that one of my remingtons is a mediocure shooter anyway and i guess theres a chance it will do better with this new barrel.
GooseGestapo
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I own a .300RUM.
I say go for it, if it's in a Rem. M700 action.
I suggest that you check with Widener's Shooters supply, and Jeff Bartlett at www.gibrass.com for some of the surplus powders. WC-872 is currently available. It's a surplus .50bmg powder and is available for ~$8lb.
I'm running WC-860, a non-cannister version of what Hodgdon sold as H870. I'm getting full .300RUM velocities with 180gr and heavier bullets and accuracy to what the rifle is capable of (factory Savage M110 w/26"bbl). But, it IS TEMPERATURE SENSITIVE...
Since you already have a couple of 7mmRemMags, I think it's a logical choice....
Initial cost of brass will be your only significant expense.
Look closely at the reloading data. Sources such as Speer's latest paint a "gloomy" picture because they use Federal cases (heavy-low volumn), CCI magnum primers (do use Fed.#215 or Win Magnum primers), and a 24" bbl. I get a full 200fps more velocity with RL25, Retumbo, and WC860 than what Speers manual suggest with the .300RUM. I suspect you likely will too, with a longer barrel.
I say go for it, if it's in a Rem. M700 action.
I suggest that you check with Widener's Shooters supply, and Jeff Bartlett at www.gibrass.com for some of the surplus powders. WC-872 is currently available. It's a surplus .50bmg powder and is available for ~$8lb.
I'm running WC-860, a non-cannister version of what Hodgdon sold as H870. I'm getting full .300RUM velocities with 180gr and heavier bullets and accuracy to what the rifle is capable of (factory Savage M110 w/26"bbl). But, it IS TEMPERATURE SENSITIVE...
Since you already have a couple of 7mmRemMags, I think it's a logical choice....
Initial cost of brass will be your only significant expense.
Look closely at the reloading data. Sources such as Speer's latest paint a "gloomy" picture because they use Federal cases (heavy-low volumn), CCI magnum primers (do use Fed.#215 or Win Magnum primers), and a 24" bbl. I get a full 200fps more velocity with RL25, Retumbo, and WC860 than what Speers manual suggest with the .300RUM. I suspect you likely will too, with a longer barrel.
Lloyd Smale
Member
well i dug around the loading room and found some ultra mag brass i thought i had stashed somewhere. I mocked up three differnt bullets seated to the crimp grove and they all fit in the existing 7 rem mag magazine box and fit the bolt head so id have to say at this point all i need is the barrel. By the looks of it if a guy wanted to seat a bullet out any farther then the crimp groves hed need to look at a bigger mag box but in my experience most remington rifles are short throated anyway.
MachIVshooter
Member
May as well go .300 Ultra. It's still overbore, but offers more advantage over the 7mm RM than the 7 RUM will.
Seriously, check ballistic tables and reloading data; The RUM doesn't gain much for all the cost of the conversion and the extra 30 grains of powder you'll be burning.
I'm a big proponent of high velocity cartridges, but there is a point of diminishing returns. The 7mm Ultra is like necking the .30-06 down to .22 caliber; It gains very little over the .220 Swift, at a cost of powder consumption and throat erosion.
The .300 Ultra will get another 150-200 FPS with the same bullet weights as the 7 Ultra, and give you the option of 200 & 220 grain loads.
If you're doing the conversion on a M700 BDL, the action length will be the same and won't be a problem. Remington only makes two actions lengths--short and long--and the long action handles everything from the .30-06 family all the way up to the Ultra Mags, albeit with different bolt faces. The Ultra Mags have a rebated rim to allow the same bolt face as the magnums based on the belted H&H case, .534". You'll need a different magazine, but that should be about it.
The bigger question is why you would do such a thing. The 7mm Rem Mag is one of the most popular and versatile big game cartridges ever developed. It is supremely useful, and has a decent bore diameter to case capacity relationship. The 7mm RUM, on the other hand, is exactly the opposite. It is obnoxiously overbore, and has quickly developed a reputation and a barrel burner and one of the more finicky cartridges to load for. The 7mm Rem Mag will be with us for years to come, even if its belted case has fallen out of favor, because it has shown itself to be easy to load for, comfortable for most to shoot, and possessing a high degree of utility. You're not going to get much performance advantage from the RUM compared to the increased powder consumption, blast, recoil, barrel wear, and the cost in brass and powder. I'd keep the Rem Mag and ditch the RUM. In fact, the 7mm RUM is about as practical in my opinion as tits on a bull.
The bigger question is why you would do such a thing. The 7mm Rem Mag is one of the most popular and versatile big game cartridges ever developed. It is supremely useful, and has a decent bore diameter to case capacity relationship. The 7mm RUM, on the other hand, is exactly the opposite. It is obnoxiously overbore, and has quickly developed a reputation and a barrel burner and one of the more finicky cartridges to load for. The 7mm Rem Mag will be with us for years to come, even if its belted case has fallen out of favor, because it has shown itself to be easy to load for, comfortable for most to shoot, and possessing a high degree of utility. You're not going to get much performance advantage from the RUM compared to the increased powder consumption, blast, recoil, barrel wear, and the cost in brass and powder. I'd keep the Rem Mag and ditch the RUM. In fact, the 7mm RUM is about as practical in my opinion as tits on a bull.
Lloyd Smale
Member
Ive also have 2 300 win mags and a 300 wby and figured the 300 wby is closer to the 300 ultra then the 7rem is to the 7 ultra. I dont have any illusions about great efficentcy here guys. Biggest reason im doing it is just to have something differnt to play with. About any place i look gives it 200 fps over a 7rem and thats as much differnce as the 7rem has over the 280 or the 280 has over the 7x57. If it truely gives 300 fps more like MachIVshooter said thats a MAJOR jump in power. Thats about the difference between a 308 and a 300 H&H mag.
MachIVshooter
Member
Not that I see a problem with owning three 7 mags, two .300 win mags a .300 weatherby, but it does beg the question: Why? From a logistical standpoint, there's nothing one will do that the others won't WRT game gettin'.
NCsmitty
Member
I thought that the M700 used an elongated magazine on the RUM and H&H magnums, but apparently I was wrong, and I stand corrected. Thanks for the first hand information.
Good luck in your endeavor, Lloyd Smale. You're obviously not a stranger to large capacity cases.
NCsmitty
Good luck in your endeavor, Lloyd Smale. You're obviously not a stranger to large capacity cases.
NCsmitty
MachIVshooter
Member
I can put a .375 RUM round in my .25-06 mag from the bottom. Of course, the fat case won't fit through the feed lips.
I do believe you're right, however, on the DM models. More specifically, I don't think any DM models were ever made in 8mm RM, .375 H&H, .416 RM or the Ultra Mags because the detachable box encroaches too far on the ends.
There is a company doing detachable 5 and 8 rounders for the RUMs:
http://www.stockysstocks.com/servlet/the-473/Wyatt's-Outdoor-Detachable-Magazine/Detail
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Lloyd Smale
Member
I was looking at midway and they do sell a ultra mag specific mag box and follower. I have to wonder if its a bit fatter rather then longer or maybe it is a tad longer. I seated the bullets i had with crimp groves to the crimp grove and they fit but barely. those are both things that can be cheaply bought if needed. What has me worried are the feed lips on the action. I dont know if remington opens them up or not. I did some rough measuring both on this 7 mag and my 8mag bdl and they seemed the same but the ultra mag is a bit fatter round then the 8mag. As to why so many mag rilfes. Ill say this. First i own 7 44 mag handguns right now and a total of about 75 handguns and can only use one of those at a time too. I just like guns and dont need to justify buying another. I do it because i want to. Also I do crop damage deer shooting every year and get the oportunity to shoot probably 50 deer a year and its fun being able to try differnt calibers and loads and differnt guns.
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