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The Optimum Velocity

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wyshadow

wyshadow

Member
May 11, 2015
1,697
238
Las Cruces, New Mexico, United States
I have to admit before I got in to airguns, I knew nothing about airguns and traditional firearms. I grew up shooting my dad's 10/22 ruger, my grandfather's double barrel shotgun, and of course shooting my brother's assortment of pellet and BB guns. After I decided to become a stay at home dad, I got in to airguns and I gain so much information in this hobby that I transferred over what I learned from air rifles to powder burners. But there is one thing I don't quite understand with air rifles but it is always done with powder burners and maybe someone here could help me out. When I got started in reloading for my 22-250, I first got the manual and study it. I went out and bought three different powders, two different primers, and about seven different bullet types and weights. I spent hours making bullets that had a combination of bullet type and weight, primer type, and powder charge. According to the manual, the book will tell you the safest charge you can test for each bullet by giving you what charge to start and will tell you how much powder you can safely use. After I made hundreds of rounds to test and found the perfect bullet recipe, I did it all over again because a shooter at the range told me about measuring bullet jump. So I went back to my mad science layer to start the test process again. To some extent, air rifle enthusiast do the same thing but except for one thing: pellet velocity. My question is, What is the optimum velocity a pellet should travel at for each round? I do understand the pellet's velocity shouldn't exceed the sound barrier but is their a general speed area we should have our pellets. The reason why I'm asking this question is because when I set my velocity on my guns and I know it's shooting good, I just leave it where is at and never mess with the speed again for fear of jinxing the gun. I watch a lot videos where the shooter will test a batch of pellets and choose the pellet with the best group but what I don't see is the shooter testing each pellet at different velocities. Maybe the pellet that didn't do to well was because the gun was shooting the pellet to fast or to slow.
 
I can see my question could have a lot of different answers so let me narrow it down. I believe most of us shot jsb pellets. What should be the optimum velocity for a .177, .22, .25, and .35 jsb pellet? For my marauder .25, I have my pellets shooting out at 892 fps. For .35 cricket, I have the gun shooting at 761 fps. Are these two pellet's velocities to slow or to fast? If I find I get poor results if I increase the speed, would that give me a clue their might be something wrong with my gun because that pellet should be traveling faster with a stable flight?
 
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All guns, barrels, pellets, etc, will dictate what each combination needs for optimal performance as stated above. If I were to try and answer in the most general way including all calibers from .177-.30(calibers I have experience with)850-900 seems to be a good goal to shoot for. With that said, my p-rod shoots boxed premiers at 705fps and it shoots them very well. Another one of my .22's can shoot the same pellets to the same level of accuracy at 910fps.

If I am thinking about building a gun or trying a certain pellet/bullet, that thought only becomes reality if I know that I can achieve atleast 850fps. This is just my opinion and is based on my results and experiences thus far. It seems to be undeniable that any pellet that is bullet like(jsb monster .22's as an example)will perform well at speeds above 900 as do every bullet I have ever tried in an airgun.

To truely achieve optimal velocity, I feel video analysis is the key.
 
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I'm finding a good "average" velocity for pretty much any caliber is around 900 fps. My .25 wildcat shoots 25.4 gr. Jsb around 910 fps. The jsb heavies around 800fps. But now I increase the velocity for the heavies up to 900fps. The heavier pellets can shoot at geater velocities and still be accurate. I would like to shoot the heavies at around 930 to 950 fps. Shooting at too high velocity makes the pellets do weird things and makes them inaccurate. Overall from what I gathered on these forums and from personal experience the best average velocity is around 900 fps
 
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I tightened the hammer spring all the way, but now I'm not exactly sure of the velocity. I've been using a chrono app for velocity. Before I adjusted anything I tested it and it read from 880 to 912 fps. Which is about right. After I tightened the hammer spring it read from 876 to 900 with the heavies. I just tried it again and its only reading 854 to 877. What I need is a real chronograph. If anyone with a .25 wildcat has done this I would like to know the velocity their getting by tightening the hammer spring and shooting the jsb heavies. Thanks
 
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Just as a point of comparison and maybe it has nothing to do with airguns, but some years ago when I was heavily into smallbore and anything .22 lr it came to be known that some ammo needed faster or slower twist rifling. The CCI stinger needs a 1 in 12 twist for stability compared to a standard 1 in 14. I remember reading about a 60 grain .22lr round that had the tendency to keyhole when shot from a 1 in 14 twist barrel and I think it was found to behave better with a 1 in 16. I may have the speed of twist on these two examples mismatched, but you get the idea. http://www.gunsandammo.com/ammo/pair-barrel-twist-rates-ammo/
 
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