The Shamal from Air Arms is a precharged pneumatic (PCP) rifle that was unknown to me and I had to figure out how to best test it.
This report covers:
- PCPs
- Shamal
- Chronograph
- Daystate Huntsman Mark 2
- Point
- Multi-pump pneumatics
- Finding the max number of pump strokes
- What to expect from a multi-pump
- Single stroke pneumatics
- Summary
Today we look at pneumatics that are unknown to us and discover how to test them. I said in Part 1 that spring-piston airguns are where unknowns happen most often, but don’t overlook pneumatics. They can fool you as well.
PCPs
I’ll start with PCPs that are the oldest type of airguns, yet the modern ones are also the newest—having started in 1980 when Daystate converted a tranquilizer dart launcher into a .22 caliber pellet rifle. It was called the Huntsman and I had one as my first PCP. From it I learned that all PCPs do not operate on a 3,000 psi fill.
Shamal
The Huntsman experience prepared me for the Air Arms Shamal that came along later. Let’s read what I said about it in my report dated May 16, 2014.
“The Shamal wasn’t the first PCP I ever owned — I think it was probably the second. I remember receiving it and discovering to my utter surprise that the rifle shot very slow with a fresh 3,000 psi fill. So, I recorded the velocity of each of the first 66 shots and learned that the rifle didn’t really come up to its power band until somewhere between shots 29 and 38, depending on how tight I wanted the power curve to be.”
“This rifle didn’t come with a manual, so when I got it I had to discover the pressure curve on my own. I did, and it turned out the rifle wanted an initial fill pressure of 2,600 psi”
The shots listed below are within the 66 shots, but I numbered these at the point where the velocity had risen to a reasonable level.
Shot Vel.
1 742
2 740
3 748
4 744
5 745
6 746
7 757
8 754
9 748
10 763
11 774
12 775
13 770
14 771
15 —-
16 772
17 —-
18 782
19 782
20 790
21 780
22 801
23 791
24 804
25 806*
26 793
27 800
28 799
29 801
30 —-
31 —-
32 782
33 788
34 778
35 775
36 775
37 769
*Fastest shot
That’s what I went through while learning the Shamal. Fortunately I knew that other PCP rifles perform well on lower fill pressures, so once I saw the chronograph numbers I was able to make sense of things.
Chronograph
Are you seeing the importance of a chronograph? With the B15 I first had to get the rifle to shoot a pellet, but after it did a chronograph was important for all that followed. With the Shamal I wouldn’t have known anything unless I used one, because every shot sounded the same. This is why you can’t rely on numbers like the fill pressure, alone.
Daystate Huntsman Mark 2
I got a new Daystate Huntsman Mark 2 PCP to shoot field target with. That rifle did come with a manual and also had the maximum working pressure (MWP) engraved into the receiver. The max working air pressure was 2650 psi. It gave 24 solid shots and I could squeeze two more out if the targets were close enough.
Point
The point of this discussion is that you need to establish what air pressure a gun needs to be filled to and it won’t always be what you think. When you know nothing about the PCP it’s best to have a way to test it, and the chronograph is a good way. Never forget the lesson we learned with the USFT that uses 1550 psi to get 50+ powerful shots,
Multi-pump pneumatics
Though multi-pumps are pneumatics they are different than PCPs and there can be surprising things about them, as well. For starters, not all of them can be pumped at all times. Many multi-pumps must first be cocked before they will accept a pump of air. This has become more common today than in the past. There once was a time when Sheridan Supergrades seemed broken because they wouldn’t accept a pump of air without first being cocked.
Another curiosity is the maximum number of pump strokes each multi-pump will tolerate. A Daystate Sportsman Mark II tops out at 5 pump strokes, while a Benjamin model 700 will take as many as 20. Many top out at 8 strokes, but some can take 10. The Yehwa 3B Dynamite requires 150 pumps to be filled all the way!
Finding the max number of pump strokes
If you don’t know the max number of pumps for a particular airgun, a chronograph will once again help. Start with three pumps and chrono the velocity with a pellet. Increase by one pump stroke until the amount of the velocity increase starts to taper off. When each additional pump stroke adds less than 10 f.p.s., stop. You have reached the maximum. Personally I would then back off to a lower maximum number of pumps as maximum for that airgun.
What to expect from a multi-pump
For smallbore multi-pumps the most power I’ve seen a .22-caliber rifle achieve is just over 25 foot-pounds. So, go into testing expecting that or less. From that you can determine the velocity to expect from pellets of a given weight. And there are some simple caveats you can apply.
For example—expect a vintage multi-pump to generate less energy than a modern one of the same caliber. A modern .177 multi-pump may get up to 12 foot-pounds. A vintage one in the same caliber might get only half of that. And these are just rough estimates. The chronograph will give you the precision.
Single stroke pneumatics
I only have a little to say about single strokes. Their power will always be low. Expect 5-10 foot-pounds from rifles in their prime and 3 to 5 for similar pistols.
Single stroke pump cups harden over time. To generate more power, pump them almost all the way five times to warm up the pump cup and then pump all the way to shoot. That will get you a significant velocity increase.
Summary
The pneumatic seems easier to test than the spring-piston airgun, to me. But that may just be my personal experience speaking.
yesterday i had a chance to cut a spare 2240 barrel to match the length of the rear spring guide from the optimus since the aforementioned one piece guide/ end cap wasn’t compatible with the mtr77, and weld a washer to the end of it. i’ve only welded a few things before so it’s not pretty, but it is straight/ true/ perpendicularly plumb, and it works. so far i’ve only cocked and fired it out of the action with a q tip as ammo into a pillow to make sure everything worked. it has since been fully reassembled. i hope to sight it in during daylight outside since yesterday i completed the project around 8 pm.
springman3000,
Congratulations! May your work perform as you hope.
Siraniko
with the rear sight adjusted fully to the right it was still hitting left of the bullseye, i made some shims from an aluminum can but afterwards it was getting too cold for me to shoot more. i’ll try again in a day or two. easy to cock and i estimate its’s power is probably where i want it but i don’t have a chronograph. easy and fun to shoot so i’m happy, just need to get it fully on target.
springman3000,
You may want to check your barrel alignment if you have shim that much along with the extreme adjustment of the rear sight.
Siraniko
that’s a good point, i hadn’t even considered it. i don’t have previous experience with well used break barrels. the stock is held together with quite a few screws and i’ve already had it apart twice. once for the initial change of the spring followed by a reassembly upon discovering the optimus spring guide didn’t line up, just so i couldn’t misplace anything. if the sight shims don’t get it on target, and i find it’s accuracy inconsistent beyond that i’ll have to take it apart a third time. hopefully i can find either brass or high quality plastic washers locally.
as much as it pains me to take it all apart again, the more i think about it, that’s probably the best course of action. i’m going to take the barrel pivot washers out of the mtr77 and bring them to the hardware store and try to find something that works. i should also compare the ones from the optimus. maybe they’re compatible and i can just switch them over. either way brass is probably better if i can find one that works from what i’ve read
Tom,
Thanks for giving pointers regarding MSPs. I’m going to apply the same principle to my own as that there is no documentation available regarding our locally made MSP rifles. Who knows I might end up submitting it as a blog article?
Siraniko
Siraniko,
I once owned a Philippine-made multi-pump. It took 30 pump strokes to fill.
BB
Siraniko,
Please do! I have a small bit of experience with multi-pumps as I have a 101 rifle and four Benjamin pistols. I am not a big fan of them, but they most certainly have their place. If I find my round tuit and get them all working properly, I just might change my mind about them.
BB,
I think you would have enjoyed being an aircraft troubleshooter. Great analytical mind that thrives on challenges.
Come to think of it, so would most of the people on this blog. Especially if you were one of those kids who took apart your toys to see how they worked or wanted a toolbox to fix your bicycle.
Good clear information. All you need to know now is what pellet or BB works best in it and which way it likes to be held to obtain its best accuracy.
And then perhaps how high a scope will need to be for proper eye alignment and relief and then find the best stock length adjustment, if it can be done.
Then there may be the noise to deal with and adjust.
BB,
Your test method is very similar to mine. That is how I learned that my old .177 Talon SS liked being filled to only about 1900 PSI to be at the top of the shot curve.
I know, with the advent of better regulators, the shot curve is flattened out and fill pressures can go higher. The question becomes, do you really need that?
Personally, I have no plans of journeying more than halfway across this country to compete against airgun shooters who are not concerned about the cost of their airgun rigs or spending most of their life practicing for that particular event. I also do not have a sponsor to give me the “latest and greatest” to show off at those events.
Do not get me wrong. There are some really nice airguns being made these days. In some respects, I do wish I was a gazillionaire so I could afford these outrageously expensive airguns, scopes, et cetera. I know I am doing better than some out there, but I have no intention of mortgaging RRHFWA to buy an airgun capable of hitting the center of an X at 200 yards, when I am usually quite content at hitting a feral soda can at 25 yards most of the time.
What I am saying is, let’s get real. Being an old, fat, bald headed geezer, it is my hope to continue to defend RRHFWA from the feral soda cans and one day pass these things on to someone who will appreciate them.
Good tips here to take notes about and keep handy. One of FM’s quirks since he took up this fun hobby seven years ago – where did the time go?! – is keeping a diary of sorts about every backyard shoot, documenting airgun use, pellets, results and anything weird that happens with guns/pellets/sights/targets during the session. The notes have come in handy here and there and have helped reduce the amount of headscratching for FM, who has managed to learn a thing or two also from the YouTubers and airgun forum contributors out there. Most of the learnin’ has come from this blog, though. Long may it live.
Ditto here RR on defending Casa FM from those feral cylinders – can do! Or poke holes in Vlad Putin and other malefactors – into their images printed on target paper, that is. 🙂
FM,
I try. Just get out there and shoot some.
Again, this comment, posted just today, is but one reason I strongly advise against deleting any seemingly unimportant or unpopular portions of this blog:
https://www.pyramydair.com/blog/2020/11/el-gamo-david-breakbarrel-air-rifle-part-1/#comment-526190
My single stroke pneumatics all run around 11ft lbs depending on the pellets and have pump heads sealed with o rings. I’m not sure if 90s counts as vintage 🙂
My UK 12ft lbs Daystate Sportsman starts to vent from the pressure relief valve which limits the power on the third pump.
Timl,
Yeah. I should have added that my Sportsman was a US spec rifle.
BB
B.B.
“having started in 1980 when Daystate converted a tranquilizer dart launcher.”
Now that sounds like an interesting blog article. Must have had a big bore. I bet not many shots per fill.
-Yogi
Yogi,
It would be but I know nothing about that launcher. 45Bravo’s guest blog on the Sheridan 190 is as close as I can come.
BB
Yogi,
13mm and 0.50 caliber are common.
Check out Pneu-Dart and Cap-Chur they are still being made/used.
https://cap-chur.com/products/
https://www.pneudart.com/products/projectors/
shootski
BB,
Good stuff on what to expect and how important a chrony is.
Multipumps are flexible shooters and are a lot of fun. I have a .22 cal multi pump rifle with a Bug Buster on top and I set up the scope so that you know where your zero is at ten meters, based on the number of pumps, using a reliable pellet. This is handy and I wrote it down by the shooting station for reference.
At the Crosshairs – 8 pumps
One mark below cross hairs – 6 pumps
Two marks below – four pumps
It isn’t exactly perfect, but it is acceptable for popping paper and reactive targets.
Will