Springs & Air Compression

[JLiang]

Hey all,

I just recently finished a maintenance takedown of my FAMAS, which started when I found a few things wrong with the rifle.

Number 1, the range was paltry, and horrendously so. It was barely getting 60 ft. with full hop, and that was with me standing on a 5-foot elevated position.

Number 2, accuracy was terrible, but consistently terrible. All shots would curve right at a set angle, and continue to do so for the length of the firing set.

So, after I cleaned the everything and started putting it back together, I had a thought. I had put in a Lonex M90SP spring in order to have it CQB-worthy. The piston and piston head I also swapped out for a Magic Box POM piston and a Lonex POM Ventilation PHead, respectively. Stock cylinder, cylinder head, and spring guide. However, I noticed that the gun was getting really terrible compression.

I took apart the compression group, and cleaned out the ports off my piston head (whoops), then re-assembled. Perfect compression. I Teflon'd the CH just for good measure, then tried with the loading nozzle.

With the nozzle on, the compression was meh. Not bad, but not perfect. However, considering that I have not found an aftermarket nozzle to date, I can't really do anything about that.

So, thinking the issue was solved, I put the gearbox back together and fired a shot while blocking the nozzle. Nothing. No compression at all.

Puzzled, I tried various things for the next half hour, before giving up and putting in the stock spring that came with the rifle, which was either an M100 or M110 equivalent (can't remember). However, this got better compression; still not 'good', but after I released the nozzle, there was a 'phhut' from the piston travelling a short distance there.

Deciding to take a gamble, I re-assembled the rifle and found that on the same hop setting, the gun was shooting to maybe the 70-100 ft. range.

That's a 40 ft. range increase, just by swapping springs. I'm fairly certain most springs cannot have an effect on compression, but obviously this change has.

Is this normal? Considering the engagement distances in CQB are <60 ft. anyway, I can live with the decreased range when I swap in the 90SP for CQB use, but if there's an underlying compression issue, I want to find it.

Milking more range out of this thing would be very, very nice.

Also, the hopup is still having issues, even after centering it and sealing it with the 'Teflon Mod'. The unit is stock (and fairly certain proprietary) and the bucking is a Lonex 50D IPHU (Improved Hop Up).

Any help for this gigantic wall of text and my problems would be vastly appreciated.

Thanks in advance!