Today reader Ian McKee, whose blog handle is 45Bravo, discusses with us his puzzlement over which way to proceed with the testing of his Air Venturi Avenge-X Tactical air rifle. If you’d like to write a guest post for this blog, please email me at blogger@pyramydair.com.
Take it away, Ian
Changing paths in midstream
by Ian McKee
Avenge-X Tactical.
This report covers:
- Two masters
- Pellets are great
- Slugs for long range
- Tune for one type
- Which way?
- Tell me
Editor: I was supposed to post this guest blog while Ian and I were at the 2024 SHOT Show, but I didn’t. My bad and I apologize.
As you know I have been testing the Tactical version of the Air Venturi Avenge-X for a while. I love the gun, it shoots well above its pay grade, the quality is very good, the adjustability and modularity of the gun is unheard of in its price range.
Two masters
To say I have shot the Avenge-X a LOT is an understatement. But after wasting a lot of lead I have come to realize I have been trying to please two different masters — pellets and slugs. As I mentioned in the recent report, The natural progression of a hobby, until very recently I have been using pellets only and was happy doing so. Then I tried airgun specific slugs.
Pellets are great
Pellets are great. They are accurate; they can be shot at very low velocities and also at relatively high velocities — both with great accuracy and, up to a point, they can perform well at distances. Ounce for ounce they are relatively inexpensive compared to the number of slugs you get for the same money.
Slugs for long range
Beyond 100 yards, though, most pellets start running out of gas (well, actually air, but you know what I mean). Diabolo pellets are designed to be drag-stabilized and have a high drag coefficient, so their maximum range is limited. In contrast slugs are spin-stabilized and slip through the air with much less drag. And slugs do perform better at longer ranges,
Typically slugs like to be shot at higher velocities than pellets, so shooting groups with pellets and then shooting groups with slugs using the same settings does one of the projectiles a disservice.
Tune for one type
I have come to the conclusion that the Avenge-X deserves to be tuned for one type of projectile. When you find the one it likes best, record the settings. Then tune it for the other type of projectile and find what it likes best. In other words, set up the rifle for each specific type of projectile.
Once you have your tunes for the different types of projectiles, decide which path you wish to follow at that point in time. You can always change it as needed for the hunting season, or shooting discipline you are pursuing. That is what is so wonderful about an airgun like the Avenge-X that does it all.
Which way?
So now I am at a crossroads. Should I tune the rifle for slugs, and follow that path first, or tune for pellets and and go there first?
My personal thoughts are to tune for slugs and their higher velocity, since I like shooting at 100 yards and more. Then once I have found “the slug” for the gun, switch to low power with the transfer port adjustment, and find a pellet that likes that velocity. Since the low power setting drops the velocity about 100 fps, we should be able to find one that likes that setting.
With the new heavier pellets recently coming to market from JTS and other manufacturers the choices of pellet weights for testing has grown.
If I can’t find a pellet that likes the lower power version of the slug setting, then I can just record the settings then re-tune the rifle for pellets (that also gives me more blog opportunities).
Tell me
What are your thoughts? How should I proceed, slugs first, or pellets first? Leave your thoughts and reasons in the comments.
As always
Shoot safe, and HAVE FUN!
Ian
Editor: See what you get with the Avenge-X? It’s an entire battery of airguns in one single rifle.
Ian,
Well good luck with the project. Tuning for slugs should be relatively easy, but then to switch to low power and still be accurate, like I said good luck….
I keep thinking of the saying, “Jack of all trades, master of none.”
-Yogi
PS I understand that slugs usually like a faster spin rate than pellets do, not just forward velocity. B.B. did a blog once about how much faster the pellet is going round and round than it is going forward. One of his best!!!
Glad to see this post is finally up and running…
-Y
Yeah! They have it up and running!
Thanks, Ian, for this wonderful opportunity for us to “help” you.
If’n you was to ask me, I would try to see what I could do with the “slugs”. If I am not mistaken though, your pursuit of a “slug” will have difficulties as is pointed out by Yogi, although many of the present day manufacturers have hopefully been designing their “slugs” to be used with the same twist rate as many of the modern airguns use.
In the short time that I have been here, we haven’t gotten a whole lot of information on slugs. So, I vote for slugs first then see what happens with pellets. Thanks!
I think, tune the airgun to suit you. The happier you are with it, the more positive will your reports be.
I like a happy tale… 🙂
———-
As for shooting non-waisted, rifling-stabilised only types of projectiles, eg slugs or bullets, I would be very interested to know the barrel rifling twist rates of each of those suitable airguns. Please.
hihihi,
Read my Reply below.
Remember to show your WORK!
shootski
shootski,
thanks for your comment and yes, I did read your “Reply below”.
Here are my thoughts:
Projectile rotation is a result of the barrel’s rifling. Therefore it is it’s twist rate that determines the rotation.
That is why I am interested in the barrel rifling twist rate, especially with airgun’s that evidently work well with bullets/ slugs. 🙂
hihihi,
As sone as you add the term RATE it requires some unit of time beyond just the amount of twist per unit distance. The barrels twist remains constant but if the time taken changes the RATE of ROTATION changes.
There used to be a great animation of this but it seems to have disappeared from the Web :^(
shootski
shootski,
oops, I didn’t mean any measure of time.
I apologise for confusing with the term “barrel twist rate” when what I meant was the measure of how close the rifling spirals, ie the distance over which the rifling groove makes one complete turn.
Sorry. 🙁
hihihi,
This guy, Brian Litz, knows from ballistics: https://bergerbullets.com/the-state-of-the-art-in-rifle-bullet-stability/
It may answer your question better than i have been doing. His book(s) definitely will!
shootski
Ian,
First I want to thank you for your work and for letting us participate by sharing ideas. As for myself, being a bit selfish, I would like for you to get started on the road of slugs because, I admit, I know very little about them.
That said, the road maybe bumpy. The idea of aerodynamic projectiles is appealing but their stability is affected by shape, speed and spin. Unless different barrels are part of the tuning, this ties your hands.
“Your mission, Ian, should you decide to accept it, . . . ” (cue tune by Lalo Schifrin.)
Best luck, and thank you again!
Henry
Ian
Just for research and development in the airgun world I suggest you go on with slugs. It’s an area that needs exploring.
Come on Shootski, put the paddle aside and help me into enabling Ian. As if he needs such…
Bill,
I was working on your wish!
shootski
45Bravo,
The most obvious solution to your conundrum is one i have faced a number of times.
The KISS solution is two (or more) rifles!
I wrote a reply some year ago about tuning my DAQ’s. The first step was to determine the needed Terminal Ballistics for the target; usually caliber/Mass driven.
The second step was to find the projectile that DAQ shoots best with PERHAPS slight powerplant tuning to optimize the projectile’s External Ballistic.
Folks always get wrapped around the axel of barrel twist far TOO MUCH. Internal Ballistics takes care of projectile SPIN RATE within reason. Twist Rate selection is secondary.
Perhaps this is the point to use an example: if you have a barrel with a one in ten (1:10) twist and a pellet travels those 10″ in one second the projectile spin is ONE Rotation Per Second (RPS) IF you increase the airflow to the same barrel and you get that projectile to travel that 10″ in 1/10th of a Second the projectile will spin SIX Revolutions Per Second! The barrel TWIST is exactly the same in both cases yet the spin has increased.
You can do the math for 1/100th of a second! Please show your work!
Back to the real discussion:
Should be your choice Ian.
A wise hunter ( my Dad) once told me: “If you chase two rabbits at the same time both will elude you.”
I will be surprised if you start with a pellet tune and then raise POWER IN to get the rifle to shoot Bullets (slugs) the reverse may work since pellets are both drag and spin stabilized you will have more wiggle room.
shootski
PS: AS you well know the bullet/slug typically has far fewer points on the body for trans/supersonic shock waves to attach too or form on compared to diablo pellets; so driving them faster is less of a problem from a consistency of External Ballistics perspective.
Readership,
I made a simple arithmetic mistake!
Traveling 1 Unit (TURN) length of twist in 1/10 of a second = 10 RPS.
The second case should have been 10 RPS
Color me RED with embarrassment.
shootski
We ain’t poifect, shootski.
FawltyManuel,
So true…and lately my pencil erasers have been wearing down at an alarming rate!
shootski
I have always wondered how well boat tail bullets would fare in an air rifle. Also if dished or flat bottom slugs would have better performance. The engineer in me would love a comparison of rotational energy and linear energy of each slug / bullet of the same weight (boat tail, dished bottom, and flat bottom) as each travel from the muzzle to the target. Yes I realize that would be very technically challenging to get actual data, though approximations are only a bit of math with some assumptions.
Though in actual use the only thing that is required is the ability to hit what you are aiming at consistently.
Mike
Mike,
Boat tails work just as well inside the barrel as long as they fill the bore diameter the same as other bases in my experience. They also don’t experience blow by or the cutting that some bullets do in firearms.
(I have seen makers call projectiles boat tails that are NOT true boat tail shape they are just bullets that are ready for Gas Checks.)
Once outside the barrel the real boat tails typically have a much better BC. The confusion comes when folks try to simplify a very complex group of factors and equate weight (Mass) with required rotation rate for stability instead of the more important overall length of the projectile. To add to that is the fact that stability isn’t a fixed number of rotations but various degrees of stability found in a range of revolutions per unit time.
Beyond that you start talking about center of pressure and center of gravity and their relative location/position along the projectile centerline. The spin of the projectile slows (decays) at a far slower rate than the velocity decays on the muzzle to target flight.
I can do the velocity change since i get many data points along that path with the Doppler Lab Radar (n.b., the new little Lab Radar isn’t capable of giving you the data to calculate actual BC) spin decay measurements would require optical or other sensors i can’t afford.
Yup, the numbers on spin decay from labs (like the US Navy Dahlgren Lab) indicate less than 2% for even the longest range ballistic projectiles.
I can pass up the research costs and go with simple Rule of Thumb numbers that are almost always in that ballpark..
I totally agree with you: “Though in actual use the only thing that is required is the ability to hit what you are aiming at consistently.” I would only add; with enough energy to get the job done.
Even a minimally unstable projectile scrubs off energy at a prodigious rate.
shootski
I had forgotten about Dahlgren’s work on ballistics.
Thanks for the information
Mike
Mike,
This guy knows his stuff like i told hihihi above:
https://bergerbullets.com/the-state-of-the-art-in-rifle-bullet-stability/
shootski
Hmmm… Finally got past the “page not found” issue.
Interesting blog Ian, I’m getting less and less patient about getting my Avenge-X. 🙂
I’d say tune for slugs. The farther the distance, the smaller the target and the higher the velocities the more critical the tune.
Tune for the slug and a pellet of similar weight may shoot reasonably well (adequately accurate at closer ranges) without retuning. Depends on how much accuracy you want/need.
Cheers!
Hank
FM is a bit sluggish about commenting; no matter – go for the slugs.
Everyone,
If you can’t get back to this blog, scroll down to the bottom of yesterday’s blog — Part 2 of the BM8 and just above the comments there’s a link on the right side that leads to this posting.;
BB
Boy, you guys here do get serious sometimes.
Ian, go for the slugs first. One setting, high. Then dress it up like this. Who knows they may come out with a belt fed, select fire, slug gun for maximum fun or thinning a herd of furry critters. 😉
I wonder if R Arms Innovations (RAI) was an influencer with his Chassis? Perhaps it’s just a normal progression of PCPs with all the options available. Alot of high tech Airgunners are smiling these days.
Thanks for your time and effort Ian, and you too BB for giving us the opportunity to participate to such a high degree.
The rain has stopped but the stream of water passing through my property has developed rapids.
Very interesting chassis, i can see where you are thinking RAI.
But the muzzle device design will surely make what is a quiet rifle very loud.
I wonder what purpose the magazine serves other than aesthetics.
45Bravo
I was more or less trying out all the options possible with his Chassis and folding stock hinge adapter with the Marauder. It has about everything on it. That magazine is just an empty removable plastic airsoft / paintball? one, inside workings removed. You can store anything that fits in it, Allen wrenches, pellets / slugs, scope dust cloth, oil, whatever.
That was his first chassis design. the second, shown below, is a much simpler and lighter design. I have lots of pictures, like some with Ruger 1022 picatinny rail options installed.
That top barrel rail / cover is for a Mossberg 500 shotgun. The flash hider attachments sometimes turn out louder and sometimes not, depending on the rifle it’s used on. At least to the shooter anyway. Dulls the crack. Noise is not a problem up here for me. If you’re making it look like a firearm, throw the sound in too. Popular in Airsoft. What the heck? Just watch where you shoot.
I know very little about slugs and airguns other than what has been written here on this blog, so my vote is slugs first, but I am even more curious about how the gun will then perform with pellets at the lower power levels. Slugs for the distance and bigger critters and then switching to pellets and lower power for closer range or smaller critters or plinking.
Well, it looks like readers have spoken, slugs it shall be!
I want to thank everyone for the input.
I have a decent selection but there are new ones being released everyday.
I will start with the ones we all know, and introduce the new ones as I can acquire them.
It is time to send some emails to the manufacturers.
Ian
Just noticed, when you click on a blog picture to enlarge it, you sometimes get a small X above it to the right to close it out. Sometimes not. When you click on the back arrow it returns to the top of the blog. Not where you left off. Then I got a pop up. Hit the ESC button! Never too old to learn.
Bob M,
on my ipad, a tap on the darkened background edge, outside the enlarged picture, has the same effect as selecting that ‘x’, ie the picture shrinks back and the page is restored. 🙂
Oh, of course, this only works with pictures in the comments section.
hihihi,
That’s how I found it, accidently wandered into that area and got the popup.
Ian,
I tried to get to this last night, but couldn’t.
Yet now that I can, I will cast for more vote:
“I’d say tune for slugs.”
I don’t know much about them hence, I’d like to see more on them. 🙂
Thanking you for another great report,
dave
Ian
Late getting in my two cents. Glad you chose tuning for slugs first. It fits your current preference to shoot 100 plus yards and readers overwhelmingly choose slugs.
Once you decide which specific slug to tune there are 4 variables you can tweak as I understand it.
1- Air pressure you put in reservoir
2- Low and High port setting
3- Hammer spring tension
4- Regulator psi setting
Some may say the regulator setting takes care of any additional air pressure in reservoir but this only works for some of the reservoir psi curve. The point I’m making is there are so many overlapping variables one can only arrive at an approximate sweet spot tune.
You have your work cut out. Enjoy!
Deck
Off subject trivia topic. If BB’s were first invented in England in early 1900’s why would their size be in millimeters instead of inches? Is .177 mm a later adopted way of stating the diameter? I have looked both in history section of Tom’s blog and on internet in general. No luck.
Deck
Deck,
This may provide some answers.
https://www.pyramydair.com/blog/2015/08/the-rise-of-the-bb-gun-part-1/
BB
Mike,
You may enjoy a look: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4934320/
The key take away: “…measurement of artillery spin rate, which has long been regarded as a daunting task,…”
Lol!
shootski