LGS has a used Remington 700 in .300 Remington Ultra Magnum for $599. Stainless barrel and action, synthetic stock with blued/oxide rings and mounts.
This immediately struck me as a pretty fair deal but I was unfamiliar with the round. I initially thought this might be a good rifle for elk, as I was shopping for a 7mm or .300 Winmag for next years elk season and as a multi purpose gun for white tails and mules. I reload so ammo availability isn't really an issue, so long as I can find brass.
Anybody have experience with this round on elk and smaller deer? I know that the round is offered in three different power levels but has anybody used the high voltage level III loadings on smaller game? How are recoil and muzzle blast? Is it overkill?

Not overkill.  

AZ is home for me and a good friend uses 300 RUM for everything.  He did put a brake on it since recoil wason the higher side prior

Is the rifle you are talking about a Sendero, if it is that is a good price

I have one that I have used on some VA whitetails.  One with factory Remington CoreLokt 180gr spire points, and several with Hornady 165gr SSTs.
The one with the factory ammo, was a big (for here) 180lb dressed 10pt buck.  Shot was at about 80yds, and punched through both shoulders, deer lunged forward one jump and no further. Small entrance and maybe 1/2 dollar exit hole.  
Several smaller does, ranging from 90-120lbs with the SSTs that I reload.  Velocity is running around 2900+ on chronograph.  My attempt to download to 30-06 range with this caliber.  

Couple deer hit in neck, DRT.  Two more hit in chest at 60yds, both went down as if hit in neck.  Surprisingly, the SSTs didn't blow up on the rib hits, but looked like a grenade went off in the forward chest cavity.  On one, I found a piece of the heart about the size of a thumbnail, just the lower tip.  The lungs and rest of heart was souped.  
The other chest hit, I found a little more of the heart, a sliver about half inch thick and 2in square.  Both had about 1/2in exit holes, never recovered the bullets.

This load is using the once fired and new Rem brass, with Rem magnum primers and Retumbo powder.  It will give me less than 1/2 in all day off the bench.  Doesn't seem temperature sensitive, either.  

Rifle is a Rem 700, with stainless barrel and black composite stock, not the sendero.  Haven't done any work to it, besides playing with the trigger a little.  It works, so I am not messing with it.  Other Rem 700s I have had to get into some glass work, but they all shoot well with tweaking.  This rifle will also shoot very well with Sierra 180 GameKings.  I have used IMR 4831 in it, but settled on the Retumbo, since it also works in my 338RUM.  Oh, BTW, both of those are unbraked.  I did add a Limbsaver recoil pad to them, that was a drop in replacement.  Took a lot of the sting out of the recoil.  For muzzle blast, I use a set of Howard Leight electronic earmuffs.  Allows me to hear, and cuts the noise down, so my ears don't ring after the shot.  

I haven't shot it long range yet, but am going to get some 208gr AMAX bullets and work some loads with those and hit a long range near here.

I paid 565 in 1996 for mine.  That sounds like a good price for 2013-14.

I'll second retumbo powder being a good one. I use it on .338 Lapua and have no noticeable shift in POI in any temps, out to 1000. For large game I'd imagine 300rum being solid, for whitetail I'd ask why punish the shooter for so little in return? It's definitely a caliber that'll help a shooter develop a flinch, unless practiced with properly and often. Be sure you want to commit to that much practice or large high power rifles will almost always make your shooting worse.

300BO, Grendel, .308, 6.8 are all better deer calibers and are much less harsh on the shooter.

I used a 338 Ultra for a while and wouldn't touch another one. The recoil is nothing short of brutal (and I do take recoil with the best of them), most of these have a brake installed after a few rounds, which is a pita to the shooter and everyone around them, It's basically a hundred grain case which irritated the Hell out of me and it does nothing a 300 WTHBY can't do with none of the side effects.

Oh, I will readily agree that there are better rifles suited for VA whitetails, but as I explained above, I do like to use the bigger ones occasionally.  One day I will hunt out west and really need them.  As for smaller rifles, I do have a 243win, and 3 308s, that see most of the time afield.  My favorite for deer here, is the Rem Model 7 Stainless, with scope, right around 6lbs.  

If you need more than 600m range it would be worth looking at.

I'd not expect a guy qualified to do that kind of shooting to ask about it here though.

My thoughts on the 300RUM is it is way overbore.  A 300 Win or even the Weatherby is as large a .308 caliber I would go.  I would step up to a .338 of some sort if I wanted to go larger.  

It's a little big... You can dump an elk with a .308 and out here in the desert I've never needed that much cartridge to shoot something. It sounds like a decent price and could be a fun gun to mess around with long range shooting but it's way overbore for hunting especially deer.

get a real rifle, 30-378 weatherby  

Decided against it. Too much power for the type of hunting I usually do. I think I'll go with a 7mm mag.
Thanks for all the feedback.

Great as a long range sniper rifle, not sure about hunting applications

It is defiantly overkill for whitetail inside 500yds, but that is more opinion based on "you could do the same with less", but it's never stopped me from using it. It really shines pushing heavy bullets really fast, and it isn't as overbore as some think, most go off the conventional wisdom of big magnums. Not many have short barreled RUMs. I've had 3 different 300RUMs from 26" to 22", my current is a 22" barreled 700. It will push 185/190s around 3250fps and 208s just over 3000fps. I honestly think the extra barrel is useless especially in a hunting rifle. Velocity loss from 26" to 22" was around 50-60fps. I love the round and have been tweaking the loads and rifles I've have chambered in it since I got my first one in highschool. If I knew then what I know now I would've taken my original basic varmint model 700 cut the barrel to 22" added a Micky A-3 and been done with it.

That's what my dad shoots, but when the next canyon ridge is 1000yds+, you need all the power you can get.

Personally, I think the .300 RUM is major overkill.  I would not touch it...

The RUM has one use in life:  To impress people with massive velocity, and thereby sell rifles.  A regular plain jane old .30-06, pushing a 180 grain bullet at 2700, sometimes 2800 fps works really well.  recoil is moderate, and kills game reliably, especially with decent bullets.  It does all this with 50 grains of powder.  if you want a bit more velocity, presumably for greater range, then the .300 Win pushes the same bullet to 3100 fps with about 70 grains of powder.  The .300 is entirely appropriate on elk, and likely a significant amount of overkill on deer.

The .300 RUM?  Well, it drives the same 180 to about 3250 fps.  In order to get this increase, the powder charge is upped to 90-100+ grains of powder.  You now have a massively overcapacity case, barrel life is going to be very short, recoil is SIGNIFICANT, muzzle blast is up a whole lot, and all for another 100- 150 FPS???  Um, no, thank you.  And now your bullets are at or beyond their design limits:  Massivve overexpansion leads to under penetration, and decreased killing power.  Nice big huge crater wounds that look impressive, but are actually fairly shallow.

If you want more killing power, try a larger caliber.  Look for a .33 or .35 caliber.  Velocity is no substitute for mass.  Elk and deer can be really well served with a .30-06, .300 WSM, 300 WIN, or even a 338-06.  There is no real utility in a .300 RUM.

I've got a Sako 75 in 300 RUM, haven't killed anything with it yet except paper. Taken it on elk hunts the last two years but haven't seen any animals yet to shoot at. It's a fantastic long range, big game cartridge but it does have a little bit of recoil that a lot find too much. I'm using a 180gr Seirra with 113grs of I believe WC872 and it shoots sub MOA. That powder was dirt cheap when I bought it and works great, $32 a 8lb keg so I bought 3.

Even better get a lazzeroni .308 warbird.  180gr at 3550 fps!!!

You haven't killed any big game with a 300 Rum have you...they actually do the opposite of what you claim..they hit hard and put big game
down..I invite you to face a big grizzly on the ground at under 100 yards wit an 06..... even a howitzer doesn't seem big enough... as for longevity, mines got over 3000  hot rounds thru it and it has finally opened up to over 2 moa.. and needs either a chamber set back or a rebarrel. Yes it uses a little more powder then a 06, but  there are many brands of bullets made to handle the velocities/energies of big magnums. I have harvested everything from wolverine, fox, wolf, grizzly bears, moose, caribou with mine over the years..never been an issue if you can shoot.......

I shoot a 300 RUM and use it to its fullest.  I use 200 grain swift As and nearly always find the bullet right in the skin on the back side, which means it has expelled every bit of energy from the round into the animal.  Also I don't have to do any tracking because  it puts most critters down fast, including an 1000 lb grizzly at 10 yards coming in hot.  It is a great gun you will love it!
-JR

Or a .270, all day long