Was pondering the Leverolution .30-30 ammo, and got to thinking "M1 Carbine ammo had a round nose too, wonder if a ballistic tip HP could be loaded in it to improve the range and wounding characteristics?

With the 30car you have a light bullet at only a low to medium velocity . you can't improve much on either due to small case capacity.
In theory you could improve it some but there might be feeding issues.

       I have long loved the M1 carbine but truthfully a good bit of that joy was due to cheep available ammo. It was something fun to shoot when I wanted something more than a rim fire without chewing up lots of expensive ammo .For the present and immediate future ammo is a grim story.
       The was once available a 110gr soft point load that on paper would be a great close up self defence round and I presume a decent hunting round for smaller deer
at shorter ranges.

A HP could give you more accuracy. Thats becasue the rear of the projectile would be perfect and the HP enalbes the tooling to take place at the front of the projectile instead of the rear.

I am loading 7.62x25 Tokarev with 168 gr SMK's and 110 gr HP's. I am still working on loads but I am able to push the 110's to a calculated 1700 fps out of a bolt gun.

I started the project trying to duplicate the 147 gr 9mm subsonic with better ballistics. It has morphed into its own little project now. I am able to get .357 energy out of a rifle that is about as loud as a 22lr. The powder is burning up in the first 6" of barrel and has disipated enough by the end that it is relatively quiet.

I think if you can find a spitzer type bullet that you can load and keep the same length then it wouldn't hurt.

Dolomite

The answer is YES. But there are some buts:
The case capacity is not the real issue, its the receiver and bolt. They cannot take the increased pressure that would be required to make the round "hotter". Just as the 5.7 Johnson is ballisticly "better" than the .30 Carbine, it is limited by the strength of the gun firing the round. There is plenty of barrel at 18" for a rifle powder to develop velocity, but that powder would blow the poor little M1 to bits. Hence the powder is the same stuff as a .44 mag, essentially a slow pistol powder.

The .30 Carbine case has a useful case capacity of 1cc. Other rounds that have the same capacity are:
.218 bee
.17 Ackley Bee
.25-20 Winchester
.270 R.E.N
.32 H&R mag
.38 Auto(ACP)
.38 Super
.357 Mag (1.15cc)
10mm Auto (.95cc)
.45 Auto Rim

I think some of the thought process is: one could make a rifle round with 1cc case capacity, but then the barrel/receiver/bolt would have to endure tremendous pressure, and would have to be super strong and/or heavy in order to endure that pressure. The M1 was designed to be light and easy to handle ie light recoil. the round and rifle was designed around that overriding design parameter. It was to be a pistol replacement and just got a bit too big for the army to completely remove the pistol from service. So it is my belief that one could have a pretty potent .30 Carbine Super +p+, and you could make a custom bolt gun that could handle the pressure, but there are other rounds that would do the same thing in a lighter package. (think 7.62x39 at around 2cc case capacity)

Sierra, Barnes, Berger, Hornady all make 110grain bullets that should shoot better than the regular round nose FMJ, but as stated before, feeding will be an issue. MidwayUSA has all those in stock.

Last year I did some M1 carbine tests out to 200 yards using 110gr Sierra Varmint HPs and did not notice any accuracy difference between those and 110gr Hornady round nose FMJ.

I think a good expanding bullet can help 30 carbine's terminal ballistics quite a bit.

Off topic, but I always wondered why they invented a new cartridge for the US Carbine rather than go with 45 ACP, since it was already available and in production.

The U.S. already had a .45 cal M1 Carbine, the M1 and M1A1 Thompsons.

The "U.S. Carbine, Caliber .30, M1" offers half the weight, more penetration, better accuracy, and has 2-3 times the effective range as a .45 cal Thompson.  It filled the niche they were looking to fill.

Also, because of the design of the M1 carbine's gas piston, corrosive ammo is a no-go.  Most ammo in WW2 was corrosively primed, but the carbine's ammo could not be corrosive, so it couldn't use the same ammo even if it were in the same caliber.  Might as well make a newer more effective carbine cartrige than either retool for all 45ACP or 9mm to be non-corosive or take the very likely chance that soldiers would ruin thier new M1's in the field.

I have often pondered the possibility of the FN PS90 chambered in .30 Carbine
and using hardened steel penetrator cored full metal jacketed spitzer ammunition at around 1900 feet per second.
It is certainly do-able and in theory should be much more effective than the 5.7X28 appears to be,,,,

NO - the .30 Carbine never used corrosive primers by US manufacture!

So, you didn't read anything he actually posted, did you? because the salient line was "the carbine's ammo could not be corrosive."

What receiver did you use in building your Tok' rifle?  What barrel length did you settle on?  Pictures?