360yd crow.

[Big Al]

I haven't been out for a couple of weeks due to work and weather but got out for an hour yesterday afternoon. The scope had been off so half a dozen shots from a clean barrel to check my zero and we were good to go, the last 3 were nicely together within 1/2" so I was happy with that. After a bit of snooping around a shot presented itself and I had plenty of time to set up.

 

So heres the details;

 

.223 running 55gr SBK, the shot was a crow sitting face on at 360 yards, wind was steady 3-4mph at full value from left to right, I checked this a couple of times over 20 seconds or so. My Shooter App said 6 clicks left for a 4mph wind. I watched the bullet impact what could have been no more than 1/2" left and perfect for elevation. A very startled Mr Crow took off a flew away strongly.

 

As always after a miss I start analysing and first port of call is check the wind again, reading a steady 3mph now. When I vary between 3mph and 4 mph in Shooter its giving me 4 or 6 clicks respectively, so it looked like I took 6 when I needed only 4 clicks as the wind had dropped. So doing the maths reveals that 0.5moa over 360yds is 1.8" and if I give myself a 3" kill zone on a front facing crow then it explains the near miss. Looks like 5 clicks would have been a wiser choice and 4 would have been on the money.

 

I understand the difference between 3mph and 4mph is actually 25% but its all but impossible to perceive this difference. I also missed a 300yd magpie about a month ago now as a 2mph wind dropped of to zero. A 2mph change in wind speed seems very difficult to notice, at least for me.

 

Ive ran some numbers to see if using a heavier bullet would have helped and had I been able to shove a 75gr Amax at say 2900fps then Shooter gives me 4 clicks for either 3 or 4mph winds with a jump to 6 at 5mph. I think Im now starting to see first hand just why people choose to use heavier bullets at longer ranges.

 

So heres a question for you all;

 

How big and/or fast do you need to go before you have that little bit of leeway on shots in the 350-500yd range?

 

Im starting to wonder if Im outgrowing my 1:9 twist .223 and if so where do I go next?

[gbal]

Al,interesting..you will see why in our discussions I've been a tad sceptical of claimed consistent first shot hits on small targets at 500+,when there is any wind. Walked in ,maybe.

And my 'theory" (fact really),that velocity is an ally to 300 or so,but thereafter BC rules.

 

There really is only damage limitation for longer shots in wind.

A VERY hot 6mm (say 85g to get BC just above .40) might make 3600 fps..ok push your "AI" version,150+ more...and you still have 19 (or a tad less for "AI") inches drift at 500y in 10mph,so keep to 5mph and its still 9+ inches

Each 1mph misreading of wind is pretty close to 2 inch POI error...you have a 3 inch crow...

 

It's VERY tight....Oh,and the wind isn't steady all the way,or over time but on a 'good' shot your luck

will be in ,and the errors will cancel.

 

6.5? well,IF you can get a 100g BC .454 @ 3750 (mostly you can't,260 rem eg is 3200,AI will add say 200fps,still way short...),then your 500 drift with 5mph wind is 7 inches....(you won't of course see much,in the recoil...).

 

No doubt we'll hear of law of physics busters,but that's my opening sighter-I can walk it in or out,given good data.

 

gbal

[Big Al]

I guess maybe 500yds was a bit hopeful George given the fact that most of the time I will get one shot with no option of walking them in and how many days are dead still? then again we will have the with or into the wind shots that should help.

 

Im finding it really interesting to see just how much difference say that extra 60yds makes from 300 to 360. The same bullet in Shooter would require only 1 click difference between 3mph and 4mph so if you got it wrong again the .25 moa difference is only 3/4" at the target and would have meant Mr Crow didn't fly away startled, also had he been a side on shot it could have ended more favourably.

[Brummy Mark]

Well done!

As has been said and also drawing your own correct conclusions - wind is the enemy with small targets at distance.

I also use .223, first in 1:9 twist and the standard range of bullet weights, best I managed on windy days was 230m pigeon sat in a tree with 4-8mph winds, cold bore shot with a partner calling windage and a go or no go for the shot. Rifle was a Steyr pro hunter.

 

A while has passed since then, and Im now runnng a .223 semi custom with a 1:7 twist barrel chambered for up to 90gr vld. Now I can run 75gr amax easy, but wind is still a problem on small targets, I have far more long range misses on feathered critters than hits. I also give myself a fighting chance by choosing targets that present a side on shot as this gives a wider area and margin for wind reading error.

Better to learn your calibres drop and windage than to think that stepping up a calibre is going to perform massively better, get a cheap wind meter?

Have fun

[gbal]

Brummy Mark: sounds honest to me !

 

I wasn't advocating a move up to a hotter calibrereally-more suggesting that there is no answer -but if you absolutely must,even a VERY hot 6mm is going to struggle,and anything less than near perfect wind call-all the way out-means 500y shots probably won't reach an acceptable hit rate.

Of course know your cartridge/load parameters,practice wind reading-kestrel,but be realistic-and don't exceed the cartridge,or the rifle...remember to add in the rifle error-very ,very few rifles will be under an inch at 400-and even that is being generous with an pro rata extrapolation from 1/4 inch at 100-that's every group,too. Ding dong gongs,by all means,but try a few 3 inch ones-good luck with those!

 

gbal

[Big Al]

So heres a question for you all;

 

How big and/or fast do you need to go before you have that little bit of leeway on shots in the 350-500yd range?

 

Im starting to wonder if Im outgrowing my 1:9 twist .223 and if so where do I go next?

 

Im starting to think that this was too broad a question and now realise that 500yds looks very much hit or miss in anything but ideal conditions or a well read wind scenario.

 

Maybe I should have said out to the distance I missed at which was 360yds?

 

The drift on a 75gr Amax at 3200fps is half that of my 55sbk's running at 3000fps so in theory had I taken the same shot with a .22BR for example the crow in theory would be dead.

 

With the amount of wind drift my current set up has its going to be as much luck as skill that I hit thinks at 350+ on anything but a still day or into/with the wind. Ive had success at 350yds but it was side on and I think I must also have just got lucky. It really seems like once you get past 300 its a whole different ball game?

[Alycidon]

Run the ballistics on a 20 cal 39 gr SBK at 3700 then compare to what you are shooting, then the 20 cal 50gr Berger at 3500fps and compare that. 50s are now discontinued and replaced by 55s.

 

360 yards is a hell of a shot for anyone, wind speeds are far from constant over the length of the shot, I have seen wind flags blowing in opposite directions on a 100 yard range. Dont beat yourself up over missing it, we all do it all the while for one reason or another.

 

I would ( and did) look at the BR case, 20 has the edge drop/drift wise over 300 yards but 22BR is a very nice round, both are far far more accurate than most 22,250 /22 Swift and you usually get to see the impacts. Both have more capacity than your 223 and will drive similar bullets faster and flatter all be it at the expense of a shorter barrel life. You would need a single shot action as they dont feed nicely from mags. A single shot helps accuracy as there is more rigidity in the action on firing.

 

A

[Big Al]

I already ran the numbers on the 39 SBK @ 3750 and although flatter and drifting less than my current outfit the numbers are not significantly different enough to have made that shot a hit instead of a miss in those conditions. Shooter still shows 2 clicks difference between a 3 & 4mph wind. Now the 55gr Bergers running at 3400fps through a 20BR are significantly better than the 39SBK's and are right on par with a 75gr Amax @ 3200fps. The other issue I have of course is accurate BC's, I have read that the 39SBK's are optimistic and Litz has his own lesser figures for the 75Amax so again how accurate is the BC for the new 55gr Bergers?

 

This is my first year of long range varminting but Im far from daft, learn quickly and tend to look at the laws of physics rather than some of what I read or see online. Im keen to upgrade my rifle for something that would give me an edge over my current set up but it has to be an edge if that makes sense, not just a change of caliber hence my PM to you last night regarding the 20BR.

[Brummy Mark]

Brummy Mark: sounds honest to me !

 

I wasn't advocating a move up to a hotter calibrereally-more suggesting that there is no answer

 

gbal

I know you weren't

I added my comment more as an outloud thought, I also thought the exact same thing, and for a while was toying with going down the 6.5x47 for longer range smaller targets, then I woke from my daydream and realised this was going to be an even more expensive lesson!

 

As an addition to 75gr amax and speed in .223, I have a nice accurate load that's been tested out to 830yds, not very fast though:

N140 24gr

COAL 2.545 (could go up to 2.585 max to lands)

Rem 7.5BR primers

Lap match brass.

 

7C -2577fps

16.7C 2608fps 985.5mb

 

drops that were different to Ballistic AE output,100yd zero:

810 yds was 27moa

830 yds was 29moa

 

These were on gongs, so the 2moa difference may be misleading really.

 

The reason I have added this info, is that I have struggled to get close to 2900fps without signs of pressure, let alone 3000fps+, I also didn't hit any other accuracy nodes that were any better than the load I have, which importantly, I can use all year round regardless of temps (so far anyway!)

[Big Al]

The 3200fps was in relation to .22BR which seems possible Mark but 20BR with 55gr Bergers at 3400-3500 looks even more fun

 

All this said of course, I may just as easily have missed with any caliber as Im not a machine so human error has to also come into it.

[Brad Y]

I have shot a 223 and 20 practical side by side. The 20 prac of mine was using 39gr sierras at 3700fps and the 223 was using 50gr nosler BT's at 3300fps. At 250 meters we had set up on a rabbit warren and took turns shooting each others rifles in a cross wind. On paper the 20 practical should have eclipsed the 223. But in all honesty the slightly heavier bullet really held its own and performance was deemed the same.

 

I now have a 6mm dasher that shoots 87gr vmax at a mild 3050fps in a 21 inch barrel. In the wind I find there 'aint no replacement for displacement'

[Big Al]

I remember reading somewhere that the BC of 39gr SBK's was not quite as good in the real world as the figures would suggest?

 

Im tired of doing comparisons only to wonder just have close the quoted BC's actually are?

[gbal]

OK,interesting.I read these posts as:

Brad confirms that to 250/300y most likely cartridges are in effect equivalent,and beyond that a 6mm Dasher reduces the probable wind error a bit...

 

Mark suggests absolute velocity isn't the holy grail,though High BC might be,and a 223 can hit gongs at 830 yards (size of gong? and with walk in?

 

Al and I think that the margin for error in shooting 21/2 inch wide crows at 500 yards in wind is extremely small,and most shots will exceed this margin;Al with 223 in field ,and I'd add hot 6mm (or anything,really) .

 

250 is relatively easy,500 is very challenging,800 is doable with bigger targets.So,be realistic?

 

gbal

[Brad Y]

End of the day my belief is the light projectiles will lose velocity quicker and thus be more wind affected. Saying this Im actually going back lighter in bullet weight for spotlighting at night for ease of spotting hits through the scope. If its windy and foul weather its nicer to stay home and enjoy a scotch instead of spotlighting. Most of our shooting is done at night or when weather is fine enough to go.

 

I dont use calculators to give me a windage value to wind on for most shots, i make a call and hold for it and learn from missed shots. First time I did this I had a 270m crow explode into multiple pieces in 20-25km/hr winds! (the hold was intimidating to make but was very effective) The first time I used a calculator I wound the wrong way and looked like a fool! Not suggesting any one method is right but I like being able to put faith in the skills I learn by missing shots. Note if I were shooting an animal that could be wounded and escape then I would think a bit more about it before taking the shot. Crows and rabbits are still dead if your hit isnt quite center mass.

[Alycidon]

The 3200fps was in relation to .22BR which seems possible Mark but 20BR with 55gr Bergers at 3400-3500 looks even more fun

 

All this said of course, I may just as easily have missed with any caliber as Im not a machine so human error has to also come into it.

 

 

55s at 3500 would be a pretty hot load in 20BR, if can be done yes but perhaps a bigger case may be better, perhaps the 6x47 case. Barrel life at that sort of heat would be 800/1000 rounds I would think. Using my usual 50gr load under a 55 I would expect a 300fps drop in velocity maybe more, so down to 3200 approx. Pressures would also be quite a bit higher. On my rifle I am on the edge of showing pressure signs in the primers with 50s at 3500. In the US some are driving the 55 at 3700/3800 using the 6x47 or 22.250 case both necked down.

 

http://www.saubier.com/forum/showthread.php?t=22619

A