I rarely shoot varmints, mostly just coyotes, but I went with some friends today and really got into it. I have a 220 swift, my question is what is your opinion on the ulimate varmint gun and why.

Depends on what varmint you are banging. I like 17s, 20s and 223s for PD size of varmints and I also use all of those for coyotes. But is I am serious about killing coyotes, I only use 223s, 22-250s and 220S guns. I use a 223 AR at times and it shines on multiple coyotes coming to a call. But most of the time, I use bolt guns.
I just packed for a coyote calling trip to Ks, and cased a 20 Vartarg custom on a Sako A1 action and a Rem 700 220 swift.
My son packed his AR.
If I could only have one varmint gun, it would be a bolt 223.

A 270, LOL. Now I like the 22-250, speed, accuarcy it has it all. Mine is a heavy barreled M 70. What is nice about the rig is that I can see the impact when shooting 50 grain bullets. I tested 55 grainers first then 50 grainers. The 50's shot better in my rifle, and I noticed that the crosshairs did not "jump" as much.

I have used the 223's a lot as walking rifles, they are tuff to beat. I also used a M70 243 with a semi heavy barrel. It got fed 70 ballistic tips, they flatten yotes.

A good friend of mine used a 243 all the time for yotes. He said it performed better at longer ranges then a 22-250. Then he got older and started to use a Tikka in 22-250. All he uses for bullets are ones with plastic tip, no hollow points. He says hollow points are not as reliable. I figure he has been doing it for 60 plus years, so he knows.

Exactamundo.....

If you already have a sporter weight 220 Swift you are all set. If you are going to do high volume prairie dog shooting a heavy barrel 223 will let you see the bullet impact through the scope and it won't heat the barrel as fast.

To me the ultimate varmint gun is determined by what varmint and what the condition's are.

A few years ago we went to help out a rancher that was over-run with prairie dogs, it was 95 degree's outside and even shooting my triple deuce the barrel was hot in 5 shot's. the ultimate gun that day was the 17HMR as we shot at least 10 times the dog's we would have with any center fire.

On the other end of the spectrum me and my nephew were shooting rockchucks at 2100yard's and on that day my 338 LapuaAI was the ultimate varmint gun.

So to me the ultimate varmint gun is at a minimum 10 different varmint gun's.
hope this help's

It depends if you are a varmint hunter or a varmint shooter. Two different disciplines.

Perzactly. I have an itty bitty riihimaki 222 for walking/calling and a 15lb wide flat forend pure bench gun in 223 for sitting and shooting from a bench. Right now missing a true looooonnngggg range rodentbuster, when funds allow will build a big, heavy fast twist 224TTH. My newly aquired lightweight 6mmAI might be accurate enough to fill in during the interim, have yet to shoot it and see.

What prairie dog shooter said...with the Swift for coyotes, you could use the .223 for small high volumn shooting..then the next step would be a .25-06 or above for long range coyotes..

I used to shoot high-volume varmints (prairie dogs and gophers) exclusively with a .22-250 Rem or .22-250 AI. Over the years I found that I did not need to burn 35 to 45 grains of powder on every shot to kill a small rodent. I found that even a .223 or .204 is usually a bit much. Barrels heat up and you either have to put down the rifle for a time or you have to rotate to another rifle or two so that you can keep shooting. I probably use my K-Hornets the most. Next comes the 20 VarTarg. The results of the hits are not as spectacular with the smaller rifles (though the VarTarg shoots a 32-grain at 3850 fps), but the enjoyment factor is still high, plus I do not replace barrels every other season, either. Save the Swift for coyotes.