Spring M rating in relation to bolt action rifles

[Reef]

I understand that the spring M rating refers to meters per second, firing .20 BB's in an AEG rifle.

So I worked out using Code Red's converter that M110 spring should give you roughly 360fps and 1.2j?

I have a M110 spring in the bolt rifle and when Chrono'd the weekend only got 1.2j with .30 BB's. I was expecting around 1.8j with this spring.

Does the M rating only refer to AEG's or all Airsoft weapons?

Have I screwed up my rifle or am I missing something?

Thanks

 

[Hudson]

It could be a variety of things.

A poor air seal, damaged bucking, using a shorter barrel (generally I've found that the standard 428mm length inner for VSRs gives closest to what they should, if you have a G-spec length barrel then you'll need to go up in spring strength).

What rifle and set-up are you using?

An M110 giving 1.2J seems not too far off what I'd expect though.

 

[Colin Allen]

I understand that the spring M rating refers to meters per second, firing .20 BB's in an AEG rifle.

So I worked out using Code Red's converter that M110 spring should give you roughly 360fps and 1.2j?

I have a M110 spring in the bolt rifle and when Chrono'd the weekend only got 1.2j with .30 BB's. I was expecting around 1.8j with this spring.

Does the M rating only refer to AEG's or all Airsoft weapons?

Have I screwed up my rifle or am I missing something?

Thanks

Why were you expecting 1.8J from an M110 spring?  

 

[Impulse]

I'm assuming you don't mean that you have an m110 spring in the bolt rifle expecting more than 1.2J, because m110 would get 1.2J(ish) and that would be my expectation. I'm assuming you mean you had an m130 or something and were expecting 1.8J?

I am a gas gun person now, so my understanding of spring stuff is older knowledge, but I will attempt to give some sort of answer from my experience building spring VSRs a few years back

So, the M rating is essentially a ballpark estimate of the m/s speed of a 0.2 BB. M100 = 100m/s with a 0.2 BB, or 328fps, M110 = 110m/s, or 360fps, and so on and so forth. AEG and bolt action springs do tend to be designed differently because they are different systems, but the M rating if it has one should be the same, for the platform it's designed for. For example:

The m100 AEG spring for my m14 and the sp100 spring (Laylax use sp to denote, but it's the same thing) for my VSR are rated for the same power, but they're very different springs. VSR springs tend to be a lot longer than AEG springs because the VSR cylinder is a lot longer than an AEG cylinder, so if I put a VSR spring in my m14, it's going to have a wildly different power. The VSR sp100 spring is designed so that when that spring is compressed in a VSR with the VSR's compression distance, it will produce the force to propel the 0.2 BB at 100m/s. However, if I put that in an AEG which has a much shorter space, the spring is compressed more and therefore will produce a lot more force when extended, since the spring is compressed a lot more in that much shorter AEG gearbox. The opposite is also true. If you get an AEG spring and put it in a VSR, it will produce far less force (and will probably be less consistent too) since it's supposed to compress more and extend less, but the VSR's cylinder is massively longer. It's also why there are specific springs for the TM PSG1, because that gearbox was pretty different, though I also think it is the same for the v2.5 gearbox in the SR-25 and now I want to dig mine out again to try and fine tune the power again. Probably won't because I never use it, but you've given me food for thought.

And after we've considered all of this, then we also have to consider cylinder to barrel ratio (yay, maths!), but I don't think that's going to be the issue here. It could very much be an issue (I don't know your build so I can't say) and will be a factor when it comes to power, but I don't think it is going to cause 0.6J difference on .3s and it's a whole other thing on its own and I don't want to bore everyone here with a wall of text as I talk about it (again). Look, long range stuff is my jam and I like it, okay? ?

 

[Reef]

Thanks for the quick replys guys.

Its a TM G-spec with the following upgrades.

Action Army Hop up unit

Maple leaf 60 degree, Omega Nub

Action Army trigger unit, piston, spring guide 

AirsoftPro M110 spring in original cylinder. 

@Hudson Glad to hear you think this sounds about right for a M110 spring, it is the original 303mm barrel, it has been suggested I upgrade to a better barrel and is on the list of things to do.

@Colin Allen honestly, I don't know LOL. Putting the stats into a online power converter gave me these numbers.

@Impulse Thank you for taking the time to write the detailed responses, It's really appreciated. Although, the more you explain the more I realise I have no idea what I'm doing...  

Do you have any advice on a spring taking the above into account, standard barrel, .30 BB's? I'm thinking an Action Army M130 or M150, but as I've proven, I know nothing...

Oh, I am aware I was warned not to start fiddling at its a black hole, but honestly I'm quite enjoying learning about this!

 

[Impulse]

I just worked out what you were thinking then. m110 is about 360fps... on a .2, but I imagine the online power converter when you were running the numbers through that was doing 360fps on a .3, which would be 1.8J. This is not how springs work, so just assume the M rating is related to speed on .2s.

The best way to work out which spring is best is... trial and error, honestly. Not all springs are created equally, and there are other factors that will go into the power at the end. An m150 spring is the most accurate for getting to the 2.3J limit on a .2, but it won't work in all builds with all BB weights as there are other things that go into it. When I put an m150 spring in my VSR setup it got me to 2.8J because of my setup, while my friend needed to put an m160 in his (it was shorter). I have another with a bore-up kit that I put an m135 spring in and it was 2.6J, so I reckon I might need to put an m120 in that one to get it below 2.32J.

At least springs aren't expensive. I went through quite a few with my VSR builds finding the best ones for the builds I did.

 

[Hudson]

What power level are you hoping to achieve?

Then we can work from there.

 

[Reef]

What power level are you hoping to achieve?

Then we can work from there.

I think I'd like to see what 1.5-1.8j feels like.

 

[Hudson]

I'd try going with somewhere between an M130 to M140, and see where that lands you.

 

[Reef]

I'd try going with somewhere between an M130 to M140, and see where that lands you.

Thanks, I'm happy to do this in stages. I'll get a M130 see what I get, then maybe upgrade the barrel if I think it needs it. 

 

[Rogerborg]

Bolt actions generally aim for close to the site limit, which tends to be 2.3J (to keep well under the legal limit of 2.5J).  That said, there is an argument to be made for a lighter pull and lower energy as you can only make effective use of the extra range if the gun is very consistent.

Some people even have fun running bolt actions at regular rifle/pistol energy (1.13 - 1.2J, depending on site) so that they don't need to worry about minimum engagement distances.  There's no wrong way to play, and given the cheap cost of springs compared to just about anything else in airsoft, I think it makes sense to try out a few to see what you prefer.