Spring tuning

[KOBK81]

I'm in need of a slight fps drop of around 17fps to get bang on 350. I've seen people cutting springs but I don't like the idea of cutting it so I'm going to collapse a coil or 2. I'm using an irregular pitch m110 spring and I don't know where abouts on the spring I should collapse. Would it be spring guide end or piston end? 

[Skara]

I've always seen springs being cut at the spring guide end.

 

Cutting is fine as long as you sand the cut part to make it flat, collapsing would work too but since I haven't seen anyone do it, can't really comment.

 

I have read somewhere that a single coil roughly equals 5 fps. But I'm not sure of that either

[Asomodai]

I think you have an air seal problem if you are only getting that FPS with an M110. Open the gearbox, sort compression parts and put an M95 in there.

 

Do it once, do it proper. 

[Skara]

43 minutes ago, Asomodai said:

I think you have an air seal problem if you are only getting that FPS with an M110. Open the gearbox, sort compression parts and put an M95 in there.

 

Do it once, do it proper. 

I think he solved the air seal issue.

He's asking what to do in order to drop 17 fps.

 

I'll add to my previous post that you should go lower than 350. Maybe 340. 10 fps is literally nothing, and you'll make sure to pass every chrono test

[KOBK81]

13 hours ago, Asomodai said:

I think you have an air seal problem if you are only getting that FPS with an M110. Open the gearbox, sort compression parts and put an M95 in there.

 

Do it once, do it proper. 

M110 equates to 360 fps buy my maths and I'm getting 367fps. I fixed the airseal and fitted a M110 spring and gained 95fps. 110x3.281=360.91 

12 hours ago, Skara said:

I think he solved the air seal issue.

He's asking what to do in order to drop 17 fps.

 

I'll add to my previous post that you should go lower than 350. Maybe 340. 10 fps is literally nothing, and you'll make sure to pass every chrono test

I did fix the airseal the original o ring was like a pee in a bucket. 

[Steveocee]

Is the spring new? You could compress the spring which would save any cutting or unnatural squeezing. I do it by putting a threaded bar through the middle and then appropriately sized washer either end and then tighten until the spring is compressed. Leave it this way for a few days, remove, test. If it's still a touch high, compress for a few more days.

 

Alternatively you could just buy an M105?

 

FPS really isn't everything though, there isn't a lot you can do more with 350 than say 330. If you have a decent hop and barrel in combination with good (and heavier ammo) you'll still reach the same distances and likely out range an "untouched" but 350 rifle.

Perfect example my VSR, it "only" shoots 465fps but I still have equal if not better range and accuracy than most other guys I come across who are 500fps chasers.

[KOBK81]

21 minutes ago, Steveocee said:

Is the spring new? You could compress the spring which would save any cutting or unnatural squeezing. I do it by putting a threaded bar through the middle and then appropriately sized washer either end and then tighten until the spring is compressed. Leave it this way for a few days, remove, test. If it's still a touch high, compress for a few more days.

 

Alternatively you could just buy an M105?

 

FPS really isn't everything though, there isn't a lot you can do more with 350 than say 330. If you have a decent hop and barrel in combination with good (and heavier ammo) you'll still reach the same distances and likely out range an "untouched" but 350 rifle.

Perfect example my VSR, it "only" shoots 465fps but I still have equal if not better range and accuracy than most other guys I come across who are 500fps chasers.

Yes the spring is new it's an element spring with irregular pitch. I need to get it sorted for this weekend and my local shop only had 110 springs in and can't get any in time for then. I used to shoot air rifles and have seen people collapse individualcoils coils using heat to fine tune. Airguns use linear springs so it doesn't really matter what end they collapse. 

[Steveocee]

7 minutes ago, KOBK81 said:

Yes the spring is new it's an element spring with irregular pitch. I need to get it sorted for this weekend and my local shop only had 110 springs in and can't get any in time for then. I used to shoot air rifles and have seen people collapse individualcoils coils using heat to fine tune. Airguns use linear springs so it doesn't really matter what end they collapse. 

 

If it's new then there is a strong chance it will bed in after it's had a few hundred shots through it, you tend to lose 10-15 fps from that alone which should put you in about the right place. 

 

I don't know for certain but would be thinking about heating and collapsing as the very last thing I'd do. The heating aspect spreads so you don't know how much structural damage might be doing to the spring other than just the bit you are squashing and then as it is irregular you could end up losing only a slight or possibly large amount depending on what coil you do.

[E21A]

I’ve heated spring and compressed them a few times. As long as you have a guide to do it on it’s ok. Just got a little at a time and be very gentle.