Wind drift question

[Petrol & Powder]

I think the author of that article is talking about the effects of small caliber projectiles as they transition down through the sound barrier as they slow during flight.

THIS IS NOT NEWS!

Small bore rifle shooters (AKA .22 rimfire shooters) have known the problems of transonic projectiles for well over 70 years. This guy is using some ballistics software to act as if he has discovered a new element, cold fusion or an honest politician.
And he’s writing about it in terms of wind drift?

 

[Snakeoil]

When you toss is "air rifle" and kind of projectile weights involved, I get suspicious of velocities over 1100 fps.

I know very little about modern airguns. What I have noticed is that max MV quoted in marketing literature is often much higher than what shooters are seeing or using. I think max MV is one of those thing like HP numbers that used to come out of Detroit. It is a number that was achieved when all the stars and planets were aligned. Hence the old weasle words, YMMV.

 

[RicinYakima]

I know very little about modern airguns. What I have noticed is that max MV quoted in marketing literature is often much higher than what shooters are seeing or using. I think max MV is one of those thing like HP numbers that used to come out of Detroit. It is a number that was achieved when all the stars and planets were aligned. Hence the old weasle words, YMMV.

I always found it interesting that that my 135 HP Chrysler FH six powered Plymouth would beat 185 HP Chevy V8s .

 

[BBerguson]

Usually, (maybe always) it’s Gamo advertising these incredible speeds. It’s marketing and it sells guns to those that don’t know any better. And yes, I think they do obtain those speeds but with incredibly light pellets and it will be pure luck if you ever hit your target. Pellets start to lose their accuracy at about 900fps so when they start advertising 1100+ fps you really need to question their quality because they are selling you on fps and that’s pretty worthless in actual use. I’ve noticed some Gamo ads recently that are 1400 fps! Not only inaccurate but also very hard on the gun as the piston is slamming to a stop because the pellet isn’t heavy enough to slow it down properly. PCP’s are a different animal and avid air gunners won’t be bs’d with or sold on velocity.

I have light 7-8gr pellets that shoot really well in my FWB 124 Springer, maybe around 3/4” at 30 yards. Max velocity is about 800 fps. If I shoot the same pellets in my Benjamin Marauder (PCP), 30 yards groups will open up to 1.5” and this rifle is more accurate than the FWB. If I remember correctly, MV on these was over 900 fps which is just too fast for these light pellets. 10.34 gr JSB pellets work well in both guns.

I also have an RWS 48 springer but I haven’t found an suitable pellet for it yet. I have some coming tomorrow that are 11+ and 13+gr that I’m anxious to try in it. This is a very powerful springer and I’m hoping these heavy pellets will tame it down a little and give me the accuracy I think it’s capable of. This is a fixed barrel and it should shoot much better than it does. Of course I’m sacrificing velocity but it will be worth it.

One of the pellets I used to shoot all the time in my FWB 124 and it was always very accurate, the most accurate I’m thinking. Boxes didn’t have the weights on them and I never weighed them. They were pointed (cool) and accurate, that’s all I knew. They are probably more accurate because of the weight, weighing about 11.5 grains. I have two boxes of those coming, I’m certain they’ll shoot well and an extra box for nostalgia.

I still have a partial box of 6.1grain Prometheous pellets. These have a plastic skirt flared on both ends and a ballistic tip like insert that I‘m guessing is made out of zinc as it‘s quite hard. Supposed to be really fast hunting pellets. So… we hunted with them one night, shooting pigeons in a barn. I hit the first couple but wasn’t anchoring them. Then the misses started and we were shooting 30-60ft and couldn’t touch a pigeon. I looked through the barrel and I could hardly see through it, The plastic skirts were being shredded by the 12 groove rifling and I had a bad case of “plasticing“. Shot some lead pellets through it to clean it and went back to hitting the pigeons again and never used those pellets again. I need to post some pictures of these pellets and guns…

 

[RicinYakima]

My RWS 45 has been accurate and killed every varmint or vermin shot. Don’t care how fast it goes, but does it work?

 

[Petrol & Powder]

So going all the way back to BBerguson's first post he quoted the article:

" .....The wind drift at an MV of 1500 fps is about 50% more than at 900 fps. In fact it is as poor at 1500 fps as it is at about 600 fps for most slugs we use. You have to use an MV of about 2500 fps before the wind drift is as low as what it is at 900 fps!...."

BBerguson expressed some dismay about that statement, and I share his dismay.
The author of that article is merely using a ballistics program to feign some knowledge about wind drift.
Furthermore, the author of that article is conveying OLD information. I would venture a guess that nearly everyone on this forum is aware of the issues of small caliber bullets and transonic velocities. This is NOT new information.

The author of that article isn't saying that air rifle projectiles reach 1500 or 2500 fps but he conveniently tossed those numbers out to make his point.

 

[RBHarter]

Reminds me of a 45 Colts Carbine.........
Lotta lesson demonstrations in that one that all apply to this .
That carbine was of satisfactory accuracy at 25&50 yd and plenty for most range uses and medium game to 75 with a 1275 MV then everything goes to ..... falls apart but the bullets have .185 BCs . Wind was never an issue. Back it off to 1000 fps and it looses a little but will still be 6" at 100 which isn't bad for what the rifle is .

I've played the game looking for retained energy a lot . Fast twist 30s have been the focus but I've worked 8.5 , 9.25 , 10 and 12" twists side by side . One starts to shine just about the time the other quits .......speed , weights , shapes , powders ...... Of course air rifles take half of those out of the game . I've threatened a time or 2 to use a solid 3-4 dia length bullet in a .177 that's closer to .180 . It takes about that to start getting into the "free BC" . Fixed pressure volumes in a caliber which will get squirrelly at some point where the weight delays don't outweigh pressure rise acceleration. So internally is where the authors flaws start . You can't compare a wasp waist to a RB to a 3 dia hollow whatever even if the weights come out . The aerodynamics don't work out and the wind effects aren't even close .

Move up the weight to a fixed BC and run the speeds up and down you still have 3-4 speed points where things will be weird and out of the linier scale and it won't happen the same place per shape probably close but not the same .