Were I to fill that gap in my collection, it would probably be the .25-06.  It has stood the test of time, and I have a huge amount of '06 brass on hand that could be put to use. 

Maybe I'm showing my age, but I still find that '06 based long action cartridges can and typically are every bit as accurate, useful, and frequently superior to their "short and fat" equivalents, in all but dedicated custom target actions and barrels.  I know manufacturers have to keep coming out with new product to sell, with fancy new names and claims of superiority, but the "standard" '06 case would meet my needs just fine as a base for a .25 cal rifle, should I get that "itch."

A Savage 99 in .250-3000 would be too awesome for words.

Oh, no!  Now you have me salivating.  My wife thinks I have waaaaay to many guns now.  Bringing one home would meet with a very chilly reception. 

But adding a centerfire lever action would fill a void.  (My '50's vintage .30-30 Marlin 336, with which I killed my first buck was stolen).  That slick little 99, especially the early ones with the rotary mag, are so sweet.  And, of course, that round and that rifle are simply made for each other.  I could try to justify it by saying I'm only replacing the Marlin with something similar . . .

Neither rifle had the recoil or the muzzle blast of the .270 Winchester and both were pretty much a one shot, DRT proposition in his hands.   Ever since then I've had a lot of respect for those two calibers.  At this point my hunting collection doesn't have either of them represented but you never know - maybe someday.   

I think right there is a factor that not many people today talk about.  The 257 Roberts and the other quarter bores (Well, maybe not the 257 weatherby) are decidedly soft shooting yet still had the power to go after elk and black bear at reasonable ranges.  Also, scopes weren't nearly as common in the heyday of the quarter bores as they are now.  Your eyesight limited you to the extent that it doesn't matter that at 300 yards a 30-06 is still darn effective and the quarters are becoming marginal for elk or black bear.

Yes, pretty much everyone can 'handle' 30-06 level recoil, but it always seems when you give someone a gun that recoils a little bit less they shoot a little bit better, as well as shoot a little bit longer before really fatiguing.  This seems to be increased when the person is already tired from say hiking around in the mountains.

Now, there are some people who like recoil.  More power to them.  But generally these are guys blasting away at the range rather than going after a winter's supply of meat.

With all due respect gentlemen,  I think you all are missing the point.  I just received a Sharps 25-45 upper with a 20" HBAR Barrel and  Sharps Factory ammo in 87 grain Speer Hot Core Soft point bullets. I didn't have much hope for the 87 gr standard soft point bullet; sort of boring, nobody talks about Speer.  Everything is Nosler and Hornady V-max and now Barnes for lead free in Kalifornia. Anyway, the 25-45 was developed to use a .223/5.56 basic platform and be able to use it to hunt big game legally wherever .23 caliber and larger is required. The 6.8 requires a different bolt.
With the sharps all you need are the sizing die and seating die.  The sizing die necks up the diameter to accept the .257 bullet with no further steps. So, you can get .223 Lapua match ammo pretty cheap and have brass for your new cartridge. However, that being said, this is the most accurate round and rifle I have ever shot.  I went on line to look at what people were saying. You guys are truly misinformed, also, being ignorant and with a mob mentality, you have formed your own conclusions with absolutely no experience with the cartridge..  The lowest velocity I got was 2995.  I had 4 shots in a row at 2995 and my fifth was 2994.  As things heated up the velocity increased to as much as 3030.  That is super consistent with very minimal standard deviation.   But, the proof is on the paper. I had 5 shots go into a .25 inch group.  I had one flier I called; I am not a bench rest shooter, but an avid varmint hunter,  and I had my friend spotting me. He kept saying my shots were going through each other. Because I had a flier I took another shot and drilled it.  I was using a tack driver bag on its side for more height, so the bag was not gripping the foream (handguard) and I was balancing the rear on a suede bag. It was just ridiculously so easy to shoot this well. I was totally blown away by this combination. This cartridge could win world benchrest records with a mere mortal lead tip bullet.  This may be a one trick pony, but it's a helluva trick.  This gun can win shooting contests.  It can hunt everything from squirrels to Bears and perhaps Elk in a pinch.  Is it ideal for really large game? Probably not, but maybe if it helps you place your shots.  I'm sure a Nosler partition would do the job on just about anything.  The nickel Teflon bolt and carrier (Robar NP3 plus) practically wipe clean without solvent, but some is needed to get the bolt really clean. . So far, this is the most phenomenal shooting gun as far as accuracy and fun that I have shot in over 35 years.  This bullet has twice the energy of a 223 at 300 yards. I just wanted to share with you guys the real world of this sharps 25-45, rather than the B.S. that's been floating around by people with absolutely no experience with it.   GOOD LUCK

Snip/ You guys are truly misinformed, also, being ignorant and with a mob mentality, you have formed your own conclusions with absolutely no experience with the cartridge.. /Snip

I believe JesseL called it spot on with around 3k FPS for 87 grain rounds. There is nothing inherent in the case design OR setup to cause this to be more accurate a round than any other cartridge of the 5.56 family including the 5.56 itself. IF we are being ignorant OR having a mob mentality please point out the specific posts.   

There is a little too much product placement in your post for it to be believable. It also seems a bit fishy to have only 2 posts. 

Or it could be you are a fanboi and got your cereal pissed in, but either way we tend to try and keep a reasonable board here with honest opinions being dealt with in a mature manner. So we would appreciate it if you would attempt to do the same.     

  Like I said, .250 Savage performance in an AR. Nothing axis tilting, just nifty.

I've been here a couple of years now and I still feel squishy about posting on necro threads. New comers and opposing opinions are both welcome here, but please state your case instead of calling us misinformed. I do not claim to be an expert, merely an enthusiast. But we have a tremendous and valuable wealth of knowledge here on WTA.

Ok,  I see I came on a little strong for my first post and I am going to apologize for that.
But, I would like to clarify and reiterate.
I got my new upper and did some good testing with it and yes I am enthusiastic.  Somebody stated that my posts looked suspicious because I only had two posts.  Well, I just joined the forum, so yes, I only had two posts. This is not a commercial or advertisement, just my personal experience.  I happen to be quite an experienced hunter and shooter so I take exception to that comment to the contrary.  Moving forward......

 I went to search to see what others were saying about the cartridge and came across your forum.  I read 6 or 7 posts and what I saw were people belittling the cartridge and comparing it to the Roberts and saying there are better cartridges for certain types of hunting. 
But again, the point of this cartridge is to provide a caliber in the AR platform that makes it legal for big game in most places where at least .23 caliber or larger is required. again, using the basic AR platform with no other changes other than the barrel and able to reload ammo simply by running a .223 into a sizing die which expands the case mouth.
Comparing the 25-45 to the .257 Roberts and the 25/06 and the 6.5's and .260 etc are all irrelevant because they do not fit or function in THIS platform.  This cartridge is about stepping up the usefulness of the AR platform with minimal fuss.  The cartridge is suitable for many more hunting opportunities, from squirrels, prairie dogs, Coyotes and similar predator hunting, to deer and possibly black bear.

I wanted to share my experience and show the extreme accuracy I got from this rifle with factory ammo with Speer Hot Core bullets.  Comparing half inch groups to quarter inch groups is NOT the same thing, it's a world of difference.  And I thought it was pretty outstanding.  I thought fellow shooters would find it interesting that Speer pointed soft point bullets would shoot so well.
Thanks for listening.

Swiftkill, we are always glad to hear from someone new to the forum - even if the subject of your post is an old thread.  One of the reasons you managed to end up here is that so little about the 25-45 has been posted elsewhere that this thread stands out as one of the first group of links about the cartridge.  No problem - as I said, we are glad you stopped by to discuss it. 

Many of us are enthusiastic AR platform shooters.  Over the years the gun and all its caliber options and other variations have been discussed to the point of exhaustion.   Then we started over again.  That's because it is likely the single most popular gun in the U.S. at this point.  One of our forum sponsors is an AR manufacturer and an expert by any definition.  A number of our members routinely compete with the AR platform rifles as well as carrying and using them professionally.   As a new member I expect some of that may have gotten by you at first glance but make no mistake - you have not wandered into a nest of "Fudds" with no patience for anything not invented before WWII. 

That said, there are also a number of members here who's experience does run to decades .  I am one of them .   You are correct in stating that I have no experience specifically with the 25-45 but I routinely shoot centerfire rifles ranging from .22 to .44 caliber both at the range and in the hunting fields.  There is nothing remotely "special" about the 25-45 that cannot be claimed just as strenuously for a number of other cartridges.  I'm not throwing rocks at your chosen weapon or caliber - just making observations based upon my experience and my study of external ballistics.   I didn't "miss the point" of your earlier post and I didn't miss the point of the 25-45 in regards to making the AR platform into big game rifle legal in some otherwise restricted jurisdictions.  What I did was join in a discussion of the pros and cons of the cartridge as it was presented a couple of years ago.  I understand your enthusiasm for it but frankly your post didn't add anything new to the discussion we already had about it.   

I will stand by my contention about your hunting experience.  There is a world of difference between being a shooter and being a hunter.  Anyone who states that the 25-45 is even marginally OK for bear or elk is stretching credibility to the breaking point.  You state  that " .  .  . a Nosler Partition would do the job on just about anything.".   Those are some of my most favored hunting bullets but Nosler doesn't currently manufacture the Partiton in a .257 diameter that is lighter than 115 grains.  That doesn't work out so well in a cartridge that has to fit into an AR magazine.   At best you are going to run some other bullet of 90 grains or less which is probably fine for game the size of a pronghorn or a white tailed deer or even mule deer but, unless God himself grants you consummate skill and extraordinary hunting prowess as well as supreme luck in encountering absolutely perfect conditions for your shot - you are likely going home empty handed.  Either because you had the good sense to pass up a bad shot or because you took one with a round that simply wasn't up to the task you set for it. 

As I said before - its never a good idea to let your enthusiasm cloud your judgement.   And you can trust me - I speak from experience on that score.