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chesterch05

Random FPS Drops ZL SA58 OSW

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Can someone help me with my problem, I am having random FPS drops, current fps is around 440-450fps <AT>0.23 but sometimes drops to around 200-300fps. Can't find the problem. 

cylinder has good compression. tight barrel and bucking also has a good seal. cylinder head and airseal nozzle also has a good seal. 

airseal nozzle has good contact with the bucking. should I try replacing the bucking to a different brand?

 

the internals are as follows

SHS Cylinder head 

SHS Airseal nozzle (trimmed down to the correct size and tapered the edge)

M130 Spring

6.01 Tight Barrel

SRC Hop Up Bucking

the rest is stock. 

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A True M130 will not give you 440-450FPS.  It should be about 410-420FPS.

That is if you are chronoing with a .20 bb to get those FPS.  Or you have a really bad M130 spring and it's more like a M140.  Which could lend to the FPS issue you are having.

Then the question that needs to be answered is do you have a Hard spring or a Soft Spring.  A hard spring is usually more expensive and comes at the settled FPS.  A Soft spring is a spring that compress down to it's operating range.  Example, sold as a M100, but it's really a M120 that needs to settle/compress down to the M100 operating range.  This is indicative of a SystemA/HurricanE spring.  Unlike the Japanese springs like PDI or Prometheus which are hard springs that come at their rated speed.

 

Another issue is your piston oring is too soft and since you are driving such a hard spring, you are getting blow by...you not using a solvent to lubricate your cylinder are you?

 

Edited by Guges Mk3

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19 hours ago, Guges Mk3 said:

A True M130 will not give you 440-450FPS.  It should be about 410-420FPS.

That is if you are chronoing with a .20 bb to get those FPS.  Or you have a really bad M130 spring and it's more like a M140.  Which could lend to the FPS issue you are having.

Then the question that needs to be answered is do you have a Hard spring or a Soft Spring.  A hard spring is usually more expensive and comes at the settled FPS.  A Soft spring is a spring that compress down to it's operating range.  Example, sold as a M100, but it's really a M120 that needs to settle/compress down to the M100 operating range.  This is indicative of a SystemA/HurricanE spring.  Unlike the Japanese springs like PDI or Prometheus which are hard springs that come at their rated speed.

 

Another issue is your piston oring is too soft and since you are driving such a hard spring, you are getting blow by...you not using a solvent to lubricate your cylinder are you?

 

I'm using M130 Spring (Rocket Brand), already solved the problem, it was the piston oring lol. I bought a metal piston head to replace the stock one. now works great, could have gotten away with just replacing the oring but why not. lol.

right now im getting consistent readings at 0.23g 440-450fps <AT> 18rps. Barrel length is 363mm 6.01 tight barrel. planning to change the cylinder too. any recommendations? Current cylinder is type 0. planning to replace it with a type 1. 

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