What Sierra or Speer varmint bullets will work good in both?

What ones do you have? If the answer is none, look at Hornady.

I'm asking about weight wise.
I like Speer and Sierra.

Take it from a seasoned varmint shooter, don't chase Sierra or Speer, just get Hornady VMax 40 grain bullets and kill the piss out of them...

What's ideal in one is less than ideal in the other. If you're hellbent on just one bullet take Shrapnel's advice. But, do yourself a favor and select two good bullets at least, one for each.

Very true, but if one bullet, it is better to yield to the best performer in the Hornet, if not get the 50 grain VMax for the 22-250...

The 40 Sierra BlitzKing is just as violent as the 40 V-Max.

It also has a better chance of running in the possible 1-16/1-14 twists of the Hornets being not as long, flat based and will tolerate 22-250 speeds as well.

Get back to me when you have some experience…

Don’t know about both, but the hands-down best Hornet bullet I’ve found is the Speer 45 grain PSP (#1023.) Accurate in all four.22H rifles I’ve owned, and lethal on our big Eastern woodchucks out to about 200 yards. They might work okay out of a .22-250, but with a relatively-low B.C. of .167 it would seem like a bit of a waste attempting the ranges the ‘250 is capable of with them.
The 50 grain Sierra Blitzkings are the go-to bullets for my .22-250 and .220 Swift rifles, but the slow-twist Hornet barrels might not stabilize them; pretty hard to find right now, also.
It would probably take a lot of time and error (and $!) to find a bullet that would work satisfactorily in both those chamberings, and it being one of only those two brands would be unlikely. But good luck.

you've got some answers from guys I HIGHLY respect...

BUT.. my experiences don't necessarily mirror theirs.

I shoot a lot of V Maxes, but also a lot of Speer. I did shoot a lot of Sierra and Nosler, until under Biden they have started selling at drug dealer pricing. Shrap and BSA may be shooting sage rats at longer ranges than I do. Most of my shots are 200 yds and under. I may also have a different style of shooting than they do.

My most favorite way, is I don't Shoot the squirrel itself. I bounce the round right in front of them, so it comes up as shrapnel ( maybe that is where Shrap got his handle). This is where you get the preverbial "RED MIST" at. This way really blows the crap out of them, back east we just called it exploding... That can flip them 8 feet in the air, and/or send one half of his 20 yds to the left and the other half 10 yds to the right. Sometimes there is no bottom half or top half to even find.

Bouncing the round in front of them, the bullet hasn't got to have surgical precision. As the season gets going, and I get my trigger finger back in swing, my hit ratio is normally 80 to 90%. hence why I keep my shots to 200 yds and under.

Most of my loads are shotgun powder, instead of rifle powder. Economy, barrel life, reduced recoil, so I can see my hits within the scope sight picture, and I single shoot each shot, so I don't end up with a hot barrel with low charged shotgun powder.

The Speer 50 and 55 grain SP aren't as accurate as say Hornadys, but the Speer 50 TNT and their 52 gr HP ARE.
and I buy them in the bulk packs of 1000 bullets each. On an average year I go thru 5,000 to 8,000 round in the spring and summer...500 round days are common. Last couple years tho, its been to 2 to 3,000 rounds down range, due to schedule requirements, as I am not as retired person, although the wife thinks I am and thinks I am available for her constant needs, wants and desires.. which is ALL WORK...she wants to avoid having to do.

That is what has been working for me for the last 25 years or so. I started using the Speers back when I could get a box of a thousand, at $60 or so each, on the door step.. so I'd spend $200 or $250 once or twice a year. Get them usually for around a $100 per thousand from Midway on my "birthday" special from them.

Oh and my 223 handloads with shotgun powders, will usually equate to what your Hornet is doing. they just have 1 in 12 and 1 in 9 twists... not 1 in 16.

I wouldn't go through 100 rounds in 10 years.
Just not much shooting targets of opportunity around here.
Southern Virginia, in the Tennessee -Kentucky corner.
All hills and hollers.

I once tried some 40 Sierras loaded hot in a .219 Donaldson Wasp, quite similar to .22-250 capabilities. What I got were a lot of "blue streak" tracers and only maybe half actually printed bullet holes in the paper. Could've loaded them down to a sane level, but then I would've been encroaching on Hornet territory, so what would've been the point?

In a good p-dog town,or gopher field,you can burn 100 rounds in an hour. Given that volume of shooting we can get a pretty good idea of what a bullet will do. Price, accuracy and splatter factor favors the 40 V-Max as Shrap pointed out. Also you might want to try and hit flesh on the fly instead of some lame a$$ plan of skipping it off the ground. It works better that way.

The 40gr. V-MAX DOES have a better B.C.....