I currently have a .243 Winchester that I have shooting 55 grain ballistic tips for all of my varmint/predator shooting (which isn't a lot), but I haven't been able to ever watch the bullets impact through the scope.

Which cartridges are going to be the best for that? I am thinking I would like to have a 204 Ruger as the largest thing I hunt with my .243 is coyotes. I would think the .204 would handle them just fine. I just want to get a rifle/cartridge combo that I can watch the bullet holes in the paper or fur when they happen.

Thanks.

Key here is recoil. First, if the gun does not fit you at all, then the recoil will work against you badly... If you can get the stock so that recoil is straight back and not "up" is the best start. THEN, you need to hold down the front end of the gun. Heavy recoil reducer on the barrel. Weight in the fore end of the gun. There are several "recoil" moderators available for shotguns and work the same for rifles. Enough weight and the caliber doesn't matter, but transport becomes a pain. As you suggest, the .204 might be a great compromise. HAPPY HOLIDAYS. Luck.

AR15 in .223

I shoot a lot of sub-.22 caliber wildcats including a .204 with a minimum spec zero free-bore chamber(as in NEVER use factory ammo in it). The .204, .20 Tactical etc will move a 39 grain Sierra or 40 grain V-Max at 3,900ish fps. Even with them it takes a heavier rifle to see the hits with 40 grainers but not so heavy with 32's, the 32's by the way will chrono in the 4,100ish+ range. My .20 Tactical which is built on a Remington 700 Varmint Synthetic with a 26 inch barrel that mic's .800 at the muzzle and is a ballistic twin to the .204 will indeed allow you to spot your hit's with the 39/40 grainers. That is in fact one of the big reasons I'm so fond of varminting with the sub-.22 calibers. You don't need a spotter.
Before the cursory "the .223 is better chorus" starts (and I have no problem if a guy prefers it)here's some delivered energy comparisons.
A 39 grain Sierra Blitzking at 3,900fps with it's .287 BC delivers the following energy at distances:
300 yards 766ft FPE (foot pounds energy)
400 yards 674 FPE
500 yards 521 FPE

Off Hornadys web site the .223 with 40's and 55's energy by comparison (both bullets are V-Max's).
300yards. 40's 479 FPE 55's 576 FPE
400 yards 40's 330 FPE 55's 427 FPE
500 yards 40's 221 FPE 55's 312 FPE

The .223's are Hornady's own factory loads (their 40 grain load is faster than I get in my 40 grain .223 load and I don't shoot above 50 grainers in the .223's I have so I used their loads). The .20 load is my own for my rifle chrono'd repeatedly with an Oehler 35P and calculated off of the 'Point Blank" computer ballistics program.
This post is absolutely "not" a wizzing contest over which round is better the .223 or .204 cause I have and love both of em, they are "both great rounds". It does however appear to me that the answer to your specific question as to spotting hits in the scope is pretty clear in an objective ballistics comparison given the right weight rifles. All my .223 loads leave the target in the rifles I have. As to which round is flatter shooting and makes hits easier at distance the 40 grain .20 cal at 3,900 fps compared to a 40 grain .22 cal at 3,800 fps blows it's doors off when it comes to bullet drop especially out there a ways. Ya just can't argue with Ballistic Coefficient and velocity for light thin skinned critters. There is less fur damage also if shot over a couple hundred yards if that matters to ya. Not a lot of drama with the sub .22's, just good ole dead. Wish I'd a had one in the late 70's when fur was worth serious $$$.

When a hunting buddy told me that he could see bullets hit game I was astounded. He is heavier than me but shoots about the same kind of rifles.

Perhaps his nervous system is a little different as well.

Then I got a Kimber 84M Montana in 243 and tried the 55 and 58 gr bullets and noticed that I could see some of the bullets hit game. The comb is very high on a 84M. Perhaps what I see is the animal jump or fall. At least now I see something sometimes.

I am not sure if its that load or that I have changed with age.

What works well for sure is to turn the power down on the scope.

I would not worry about this too much.

I have a Rock River Varminter and I shoot the 50 grain V-Max bullet at 3300 fps. I can see impacts with this rifle.

I do not wish to get into the 204 vs 223 argument, but IMO the 223 with a 50 grain pill is at best a 325 yard groundhog cartridge. I do not know how anyone can consider the 204 a cartridge that will reliably kill ground hog's past 325 yards. I have shot alot of GH's, and any shot over 250 yards I deliver a double tap with my AR. If you do not double tap you will have crawl off's.

Bcause of the effective killing range of the two cartridge's it is hard to really find a dime's bit of difference between the two. I know alot of people will take issue with my statement about the "killing ability" of the two cartridge's. I am sure alot of guy's will say their rifle's are effective killer's at 400 and 500 yards. But I am not buying it. I have watched too many ground hog's in my 35 year's of ground hog hunting that crawled off. Tom.

Tom you make some great points and just for "Discussion", "Not Argument". I took the liberty of posting my personal data from both my .204 with 39 grain BlitzKings and my 50 grain V-Max load for my .223 varminter which is a titch faster than your load but close enough for government work.
Also I believe what you call ground hogs around your place are a fair bit bigger than our rock chucks and probably take a bit more thump to anchor em (just guessing there). With that in mind I'm with ya on the "effective" range of the .223 give or take a few yards. I also share your feelings that even with rodents crawl-off's are unacceptable. I too have been hunting them for longer than I'd like to admit, actually your post made me think about it and I been shooting rock chucks regularly since 1961 (scary huh?).
As to seeing one's hits I disagree totally with the poster that stated it really doesn't matter. It's invaluable to spot your own hits and misses "especially" hunting fur. I can see where your semi auto would facilitate seeing the hits as the action cycling will certainly moderate muzzle jump, especially on a good one such as the "Rock River". I hadn't considered that as all my rifles are bolt guns and most of em heavy to fairly heavy.

All that aside and just looking at your 325 yard max using working loads out of my two rifles it comes down to this at 325 yards. My .204 drops 2.87 inches less, drifts in a 10 mph cross wind 3.3 inches less, and packs 126 ft lbs more energy. The bullet weighs 11 grains less so in similar design and weight rifles the muzzle whip and resulting loss of sight picture will be more pronounced with the 50 grainer. Not huge differences for sure but every one of em as it applies to the original thread topic is in favor of the .204.
Some might disagree with your 325 yard numbers (me for one on stuff smaller than ground hogs or coyotes) and at further distance the ballistics stack up heavier in favor of the .204 the farther you go out. I've shot lots of p-dogs over 500 yards with the big .20 cals, a lot tougher with a 50 grainer in a .223.
Sure not being argumentative Tom but my experience is that if your goal is to see the hit's (and misses)with your varmint rifle the sub.22 cals. win hands down.
If other criteria is the goal it might well end a guy up with a different view point.

Here's both rounds as calculated off "Point Blank" ballistics program to 500 yards. From here a guy makes his own call.

Happy new year to ya.

Load Data
~~~~~~~~~

Name: .223 with 50 grain V-Max at 3,350 fps
Ballistic Coeff: 0.242
Bullet Weight: 50
Velocity: 3350
Target Distance: 200
Scope Height: 1.500
Temperature: 70
Altitude: 4800

Ballistic Data
~~~~~~~~~~~~~~~
Range Elevation Velocity Energy ETA Drop Max Y 10mph Wind Deflect
0 yds -1.50 in 3350 fps 1246 fpe 0.000 sec 0.00 in -1.50 in -0.00 in
25 yds -0.51 in 3261 fps 1181 fpe 0.023 sec 0.10 in -0.57 in 0.06 in
50 yds 0.27 in 3174 fps 1119 fpe 0.046 sec 0.40 in -0.50 in 0.24 in
75 yds 0.84 in 3089 fps 1059 fpe 0.070 sec 0.92 in -0.36 in 0.51 in
100 yds 1.18 in 3006 fps 1003 fpe 0.095 sec 1.67 in -0.17 in 0.89 in
125 yds 1.29 in 2924 fps 949 fpe 0.120 sec 2.65 in 0.10 in 1.39 in
150 yds 1.14 in 2844 fps 898 fpe 0.146 sec 3.89 in 0.43 in 2.02 in
175 yds 0.71 in 2765 fps 849 fpe 0.173 sec 5.40 in 0.85 in 2.81 in
200 yds -0.00 in 2687 fps 802 fpe 0.200 sec 7.20 in 1.35 in 3.72 in
225 yds -1.01 in 2611 fps 757 fpe 0.229 sec 9.30 in 1.94 in 4.77 in
250 yds -2.33 in 2536 fps 714 fpe 0.258 sec 11.71 in 2.63 in 5.95 in
275 yds -3.98 in 2463 fps 673 fpe 0.288 sec 14.45 in 3.42 in 7.28 in
300 yds -5.98 in 2390 fps 634 fpe 0.318 sec 17.54 in 4.33 in 8.75 in
325 yds -8.38 in 2319 fps 597 fpe 0.350 sec 21.03 in 5.36 in 10.42 in
350 yds -11.21 in 2249 fps 562 fpe 0.383 sec 24.93 in 6.54 in 12.29 in
375 yds -14.46 in 2180 fps 528 fpe 0.417 sec 29.28 in 7.86 in 14.34 in
400 yds -18.16 in 2113 fps 496 fpe 0.452 sec 34.07 in 9.34 in 16.56 in
425 yds -22.33 in 2046 fps 465 fpe 0.488 sec 39.32 in 10.99 in 18.95 in
450 yds -27.04 in 1981 fps 436 fpe 0.526 sec 45.12 in 12.82 in 21.57 in
475 yds -32.18 in 1916 fps 408 fpe 0.563 sec 51.34 in 14.82 in 24.29 in
500 yds -38.01 in 1854 fps 381 fpe 0.603 sec 58.27 in 17.07 in 27.33 in


Load Data
~~~~~~~~~

Name: .204 Ruger with 39 grain BlitzKing at 3,880 fps
Ballistic Coeff: 0.287
Bullet Weight: 39
Velocity: 3880
Target Distance: 200
Scope Height: 1.500
Temperature: 70
Altitude: 4800

Ballistic Data
~~~~~~~~~~~~~~~
Range Elevation Velocity Energy ETA Drop Max Y 10mph Wind Deflect
0 yds -1.50 in 3880 fps 1304 fpe 0.000 sec 0.00 in -1.50 in 0.00 in
25 yds -0.73 in 3795 fps 1247 fpe 0.020 sec 0.07 in -0.58 in 0.04 in
50 yds -0.12 in 3711 fps 1193 fpe 0.040 sec 0.30 in -0.52 in 0.16 in
75 yds 0.34 in 3630 fps 1141 fpe 0.060 sec 0.68 in -0.42 in 0.36 in
100 yds 0.63 in 3549 fps 1091 fpe 0.081 sec 1.23 in -0.28 in 0.64 in
125 yds 0.75 in 3471 fps 1043 fpe 0.102 sec 1.95 in -0.09 in 0.99 in
150 yds 0.70 in 3394 fps 997 fpe 0.124 sec 2.84 in 0.15 in 1.42 in
175 yds 0.45 in 3318 fps 953 fpe 0.146 sec 3.93 in 0.44 in 1.96 in
200 yds 0.00 in 3244 fps 911 fpe 0.169 sec 5.22 in 0.79 in 2.59 in
225 yds -0.66 in 3170 fps 870 fpe 0.193 sec 6.71 in 1.21 in 3.31 in
250 yds -1.53 in 3099 fps 831 fpe 0.217 sec 8.42 in 1.68 in 4.13 in
275 yds -2.61 in 3028 fps 794 fpe 0.241 sec 10.35 in 2.23 in 5.02 in
300 yds -3.94 in 2959 fps 758 fpe 0.266 sec 12.52 in 2.84 in 6.02 in
325 yds -5.51 in 2890 fps 723 fpe 0.292 sec 14.93 in 3.54 in 7.12 in
350 yds -7.35 in 2823 fps 690 fpe 0.318 sec 17.60 in 4.31 in 8.34 in
375 yds -9.46 in 2757 fps 658 fpe 0.345 sec 20.56 in 5.18 in 9.68 in
400 yds -11.87 in 2691 fps 627 fpe 0.373 sec 23.81 in 6.15 in 11.15 in
425 yds -14.57 in 2627 fps 598 fpe 0.401 sec 27.35 in 7.21 in 12.72 in
450 yds -17.58 in 2564 fps 569 fpe 0.430 sec 31.19 in 8.37 in 14.39 in
475 yds -20.89 in 2501 fps 542 fpe 0.459 sec 35.35 in 9.65 in 16.17 in
500 yds -24.56 in 2439 fps 515 fpe 0.489 sec 39.86 in 11.04 in 18.10 in

A 15# varmint rig in a small caliber will help spot hits...along with a quick eye in the scope..here's my 20 Practical...40 gr V max main diet....

Nice rifle. Course I'm biased. What can I say, I'm a small caliber guy?

I shoot both 20 and 25 grain bullets out of my 17 Remington in a 700 with a 10x scope as a calling rifle and impact is easy to spot.

Um not to piss on peoples chips here but I see impacts with all my rifles including my 375 H&H may be its just me, dunno.

If I dont, Ive done somthing wrong and generally it is a miss, and secondly if I hear the BOOM Ive missed as well.

Just my 2c.

To this end I am planning on fitting a muzzle blast deflector with a downward vector, to reduce muzzle lift and blast intensity, on my 303 Brit. (Something along the lines of the jungle carbine muzzle cone). They tell me that moderators work well to reduce recoil. The 'Maxim' style moderators only add an inch or two to the rifle length.