The Remington XR100 was trotted out a few years ago after big green saw that the .204 ruger was a hit. The guns heart is actually the old XP100 piston action. A scaled down bolt gun action in a bolt action pistol chambering the .221 fireball. Which the fireball is a wonderful round for varmint hunting and wildcating. The XP100 was well thought of by serious boltgun-pistol shooters it was ahead of its time in a lot of ways.
The 204 ruger was developed by Hornady and ruger from the older .222 magnum round. If you care and can not find brass like me when it first came out, you can neck down 222 mag brass the fire form it in your 204 chamber then full length size. No need for that these days, but it can be done if you get some 222 mag brass really cheap.
The 204 is a 20 caliber round that fires a 32 to 45 grain bullet and velocities that rival the 220 swift but with less barrel burning and pressure. The 204 compared to the 17 remington has less fouling, less pressure, longer case life and longer range all with better accuracy. The 204 usually has around a 4200 fps muzzle velocity but can be loaded a little hotter wit handloading. The 17 remington is the closest caliber to compare to the 204 when it comes to terminal effects on varmints. With the 17 you either get a dead animal with not a mark, or immediate disassemble of the target. The 204 is always impressive on the target. Crows look like a grenade went off inside a feathered pillow and the flatter trajectory of the .204 allows dead on aiming to ranges that you would not believe if you are used to 22.250s and .223s.

The XR-100 is the same action as the xp100 pretty much, but thats where it ends. The Rifle comes with a laminated stock with a thumbhole grip that feels great in the hand. I was never a thumbhole stock fan but this is nice. The barrel is free floated and the fore arm has the cooling slots. I have not clue why because it is a single shot bolt action and it would be real work to heat it up enough to really need them. The stock is sadly not bedded in any way which is typical for remington in those type stocks. It does not effect the accuracy of the gun in any practical way though.

The gun using my handload of Vit powder and a 32gr Vmax shoots 1/2 MOA to 3/4 MOA depending on me. One thing I notice is people tend to think their groups are worse when looking at the results of the 204 on paper. The holes are smaller so the space between holes in the group sometimes makes some people mistakenly think its not shooting up to par. On the surface it can look so so until they stop and think about the size of the holes and measure the group. A 3/4 MOA 100 group with a 20 cal looks horrible when shown beside a 3/4 MOA group from a 308.
I usually zero the .204 so I can hold dead center of a crow out to 300 yards and they have yet to let me down. That is the real benefit of the round to me more so then its terminal effects. It is easy even for a beginner to use since they have little experience judging distance and using hold.
The XR100 comes with the standard remington 700 trigger but it is adjusted to be very very light. Some feel less then 3 ponds and break like a GI Joe action figures thumb. This makes the gun a pleasure to shoot when you out good glass on it and consider its accuracy and trajectory. Opening the bolt shows the guns solid no magazine action. The gun is single feed. This is not a big deal for what it was meant for but some people would want a repeater.

The gun has a leupold VX-II 6x-18x scope on it. This scope with the target turrets has long been a favorite of mine when it comes to none tactical uses. It is attached with leupold bases and rings.
I have some strange habits when varmint hunting that some find odd but I am always trying to make it easier to hit at long range but not have to carry a lot of stuff with me. I have other uses for a back pack and if I need something out of the pack to help me usually the time has passed for the shot by the time I get it out and in play. One of my little tricks is to keep a caldwell rear bag attached to either my belt or a strap by 550 cord so it can not get lost but it is always there when I need it and has freedom to be adjusted. Since this gun has a thumb hole stock I looped the cord around the hole and kept it with the gun. It worked out a lot better then I imagined. When I move it is always with the gun and I wrap the extra cord around the stock. This is not the kind of rifle you are running around with over mountains or hanging by a 3 point sling so this works nice. And its already with the gun if I see a shot and I need to just grab the gun and get ready fast before the shot passes.

Bag is filled with foam beads so it weighs nothing but works as great support.
I always try to keep a simple set of bushnell laser range finders with the gun so I can get a fast reading if I am in land I am not used to estimating range in.

And like all of my working varmint guns I have a set of harris bipods. This rifle has the BR model which although is not the best all around model, is my favorite if the grass is not too high. The leupold sunshade is also something to consider when trying to nail crows that are smarter then your mother in law. Depending on the sun position, a little flash is all it takes for a crow to go into counter sniper mode.
The XR100 is a nice target/varmint gun and the 204 is a wonderful killer that can make you look like a better shot then you deserve. If you can find this combo and want a varminter, this is a good choice if the price is right. I have for years been a 17 remington fan but dumped it as soon as I got to work with the 204 ruger. Sure it does not have the performance and range as my 243 WCF or the complete familiarity of the 5.56 but it is worth having in every ones arsenal.