Spring gun tuning: Part 1
Spring gun tuning: Part 2 – Building a mainspring compressor
Spring gun tuning: Part 3 – Mainspring compressor continued
Spring gun tuning: Part 4 – Let’s disassemble a gun!
Spring gun tuning: Part 5 – Powerplant disassembly
Spring gun tuning: Part 6 – Disassembly completed
Spring gun tuning: Part 7 – Disassembly of other spring guns
Spring gun tuning: Part 8 – Disassembly of other spring guns, continued
Spring gun tuning: Part 9 – Cleaning and deburring
Spring gun tuning: Part 10 – Lubrication and reassembly
Spring gun tuning: Part 11 – Lubrication and reassembly continued
Spring gun tuning: Part 12 – Finish reassembly and test the gun
by B.B. Pelletier
Well, it’s time to range-test the results of our Beeman R1 tuneup. You may recall that I said I wanted to lower the power to have a light-cocking, smooth-shooting rifle. What I didn’t tell you was that my R1 had a gas spring in it before the tuneup. It was working fine, but I was tired of having to cock 50 lbs. every time I wanted to shoot. I had a special low-powered mainspring that I used with the factory piston and spring guide. After the tuneup, I knew the gun was easy to cock and shooting smoothly, but I had to take it to the range to learn the rest.
My R1 has a plain walnut stock, a Vortec muzzlebrake and a Bushnell Trophy 6-18x in Leapers Accushot medium rings. The low-power tune makes it very enjoyable.
I hadn’t counted on this benefit, but the R1 is now extremely quiet. I doubt my neighbors would know I was shooting if they didn’t see the gun or hear the strike of the pellet. After testing magnum guns for the past 6 months, it was a real pleasure to shoot a rifle this smooth and quiet; sort of the reason I got into airgunning in the first place.
Low power – but not THAT low
The tuned R1 spits out a 15.8-grain JSB Exact at 645 f.p.s., on average. That works out to 14.67 foot-pounds at the muzzle. A factory R1 in .22 caliber will generate about 17-19 foot-pounds, so this tune is definitely lower, but not so much that I can’t do the same things with the rifle. And, that was also tested at the range.
Accurate
Shooting an R1 requires a lot of technique. You simply cannot grab the stock and hope to hit anything. But, let it float and watch out! My results with JSBs at 40 yards were not as good as I had hoped. Usually, the JSB Exact groups tighter than any other pellet, but not in my R1. The best I could do was still slightly over an inch.
Beeman Kodiaks, however, brightened the day. They sailed through group after group and nothing measured larger than one inch. The best for the day was 0.847″. It looks like only four holes, but two pellets went through one of them.
Having also had some luck with heavy Logun Penetrators in the past, I tried them, as well. The best group of five measured over 1.3″. That left Kodiaks as the pellet of choice.
One of these holes passed two pellets. This was the best group of Beeman Kodiaks.
The barrel joint loosened during the shooting, so it would not stay in any position other than closed once the gun was cocked. I expected this to happen because of the lubrication. It didn’t affect accuracy, but I still tightened it once I returned home. Remember, the test for the pivot bolt being tight enough is that the barrel of a cocked gun will stay where it’s put.
This rifle is now a genuine pleasure to shoot. I am inclined to just sight it in at 20 yards and leave it that way. It might even become a “go-to” rifle, because it is just as quiet as my TX200 or Talon SS and lots of fun to shoot.
I think a lot of people would be very reluctant to have a gun tuned to lower power. I believe that this is because of a) marketing (companies sell rifles by fps and b) a lack of knowlesge of
how much energy they need to accomplish their needs in shooting.
Of course if an unruly rifle is neither accurate nor precise, then all the energy in the world won’t matter.
The real issue is what are the cutoffs for power in various calibers that you would want to stay above?
For example, you lowered your R-1 to 14.67 foot-pounds. If 14.67 is better than 17-19, then why not 13? or 12? or 11?
What exactly is it about 14.67 that made you comfortable with that number?
I assume at some point in the power curve there is a point of diminishing returns where the gun doesn’t really vibrate any less and doesn’t shoot any more accurately.
It would be interesting to hear you comment on this.
thanks
My comment is – that’s where the gun ended up. I didn’t plan on that power lever any more than any spring airgun tuner can guess closer than about 10 percent of what he will get from a tune. I was going for something in the 13 foot-pound range and that’s where I wound up.
Could I have fiddled with the tune to get a different number? Of course. Would it have mattered? As you point out – probably not.
The UK shooter have to stay below 12 foot-pounds because of their law. Is 12 a good number? Probably not, but who is to say it isn’t one (good number) of many? This is not a precise science.
B.B.
Hi BB,
As a UK airgunner, I’m used to 12ftlb and find it is enough power for the job I want it to do. I take many rabbits, sqirrels, pigeons and crows up to ranges of 40m without any trouble using my 5.5 mm Slavia 634 (11.6ftlb with 1.04 gram JSB Exacts). I find for these sorts of varmint, even 12ftlb can cause over penetration at 25m.
Accuracy is the most important asset for a hunting gun and a smooth, easy to handle gun helps me keep my shots consistantly inside the magic 1″ kill zone.
This is a great blog – Keep up the good work
ATB,
Tenuc
B.B. i have a question regarding the seal on a gamo hunter 1250 that arrived in the mail a few days ago I noticed that the seal had a chunk equal to about 1/8 the perimeter of the seal. im not sure if its leaking air or not as im not sure how to test it with a springer. should i take it to a repair shop?
thanks for the advice, scopestop guy
scopestop guy,
You test a springer with a chronograph. It’s the only way to do it. If velocity is where you expects it to be, the gun isn’t leaking.
B.B.
B.B. how could i get my hands on a chronograph short of buying one. thanks scopestop
I am A UK QB 78 owner and have been unimpressed with its power. On various sites it has been quoted with a ft-lb ratio of between 6-9. Is there asite i could vist to get detailed drawings to tune it up myself or somwhere to send it. I know this a long shot please advise.
Disapointed
Disappointed,
You need to connect to the UK tuners. The way to do that is to get on the UK chat forums.
The U.S. forums will not be as helpful because we don’t have power limits and our QB78s are much more powerful.
There is no question the power in your gun can be increased. All it takes is a valve modification.
B.B.
hi BB
im looking into tuning my gun. From what i understood so far i need tar, moly and silicone oil. is this right? Is silicone oil used for the piston seal? is it enough for a piston seal to be applied with moly or silicone oil must be also used?
thnx
Tuner,
If you use moly grease on the pistol seal like I show in the spring gun tune series, you never have to use silicone oil.
Tar is only needed for guns that vibrate excessively. Moly paste grease may be all you need.
B.B.
Hi B.B.
I own a Remington Vantage and I would not say I'm fully satisfied with it's accuracy. I've read your run-down on a tune-up but I was curious as to how much of a difference a tune can really have on accuracy. Please elaborate…
Thanks, Paul
Paul,
A tune generally has zero affect on accuracy. Unless the gun had some gross problem, all tuning does is make it shoot smoother.
Even a better trigger has little affect on accuracy, unless the original is really bad. I would stick with the gun as it is now.
B.B.
Hi BB,
I am new to the hobby. However not new to shooting nor mechanics. I grew up a mechanics son. We worked on everything from the car to the HVAC unit. At Christmas I gifted air rifles to my daughters and my wife, while in the buying spirit I “Santa” bought my self a Ruger Yukon in .22. I liked the gun and had nothing to compare it to but my youth air rifle which was a multi pump .22 crosman? Could have been a daisy.. Not sure. Well this was my first break barrel so I was very excited and immediately put it to use and started researching. I put probably 250 rounds through it in a few days. The one thing I found was it wasn’t as accurate as I would like. Inside of 20 yards it is a great shooter and I have taken pests out to 50 yards with it. However it was only after a much needed scope upgrade to a3x9x50.
Well I was running across some classifieds and found a beeman Sportster RS2 for Sale or trade. So I traded some .22 rim fire bullets and got the gun, both barrels and the Allen wrench. I brought it home and gave it a good once over. Not expecting much due to it being used and I already had a new gun. I began to shoot it. I fell in love. It’s my go to rifle. It is much more accurate than the Ruger! Not only that but it seems to have the same power. So now I tore it down, cleaned, lubed and applied loctite to specific fasteners. Well I have the fever now…. Big time! So my question is what could I do to make this gun shoot a tad stronger/faster. I intend to do the steps mentioned in your article to make it a smooth shooter.
All advice is greatly appreciated!
Thanks,
Leo
Leo,
Your comment got caught in the spam filter. I don’t know why. In any case, I’ll whitelist you. Hopefully, that’ll prevent you from going to spam, again. You haven’t gotten any replies to your comment because I found it in spam about 2 hrs after you submitted it.
Edith
Leo,
Read this report and then do it. And welcome to the blog.
/blog/2015/01/things-you-can-do-to-make-your-new-airgun-better-part-1/
B.B.
I am glad someone took the time to thoroughly explain what “Tuned Rifle” means in the air gun world.
But I must say I am equally disappointed to see that little to no emphasis actually goes into tuning anything. My background in tuning antenna impedance’s has taught me tuning is a somewhat predictable process with time. Yet it is still a grind of calculate, install, test then adjust for parasitics and repeat until the impedance is dialed in just right. That or you reach the limitations of your part values and tolerances.
I was really expecting to find some analysis well beyond thumb in the air spring replacement. Perhaps a look at metal alloy types, winding rates, metal shape. perhaps even a look into the advantages of a wave disc spring vs a standard coil. I expected there to be a discussion on trade offs in power, lifespan, vibration, torque or noise for each. I expected to find that some sort of dampeners were placed a critical areas to absorb gun specific vibrations like on a hunting bow. I suppose I expected some level of fine analysis into really improving one or more specific problems. I expected testing measurement and fine tuning to dial it in.
Instead I see nothing in these 13 posts to suggest that tuning a rifle is anything but an oil change and lube, touting itself as something far grander. No doubt you are a master in air rifle experience, assembly and servicing. I would never try to diminish your acumen into how air rifles are constructed and function. But to use an analogy, Jiffy Lube Deluxe Service is a long way from COBB engine tuning or even suspension tuning for that matter.
RecoNick,
Welcome to the blog.
B.B.
Hello,
I got a used HW80 here in the UK where we live for now. Would a change of the mainspring bring the power up to the US specs? Or would I be better off selling it and buying again in the States? Not a cheap airgun.
pacala,
Changing the mainspring does very little for the power and can even reduce it. It’s the length of the piston stroke that determines the power of your rifle.
There is no cheap or easy way to change piston stroke.
B.B.
!Thank you!
I guess will try anyways and see what happens. I know from some YouTube video that these <12 fps have such short springs that don't require compressors for disassembly!
Mine shoots and cocks very smooth, previous owner had a tuning job done on it. Do you recommend the Air Venturi spring? It's a .177 .
Pacala,
Please read TODAY’S blog. I wrote it for you.
/blog/2017/05/fwb-124-air-rifle-part-1-2/
The Air Venturi mainspring you mention is a good one.
B.B.
B.B.