Jump to content
Brian Enos's Forums... Maku mozo!

Accuracy problems with JP silent captured spring


Durtywrench

Recommended Posts

Not saying this is an issue but I can see where it could happen. With some receiver/receiver extensions, the captive spring is loose. If that happens the carrier may be in a different position on each shot.

My captive spring was too short and I shimmed it with a washer in the end of the receiver extension. I don't have any accuracy issues but the instructions cover this so it was right the first time I shot it.

Link to comment
Share on other sites

Spring weight and recoil system mass affects how long the bolt is closed which can affect velocity.

Heavier spring/more mass means more velocity.  Try it the next time you chrono.

How this affects your rifle you will only know by trying different weights and mass.

I'm not talking huge amounts but enough to see on the chrono sheet.

 

Nick

 

Link to comment
Share on other sites

I can only tell you my experience.

Had a gun that consistently was running sub to at moa.  Saw accuracy dropping off and fiddled with several variables.  Since I had a back up gun set up exactly the same, except barrel length, I had the opportunity to do some comparisons.  Everything pointed to the spring system.  With my guns, I saw a significant improvement with the heaviest spring in the captured recoil system vice the lower rated springs.  Also, on the lower rated springs I tried placing a quarter or two in the buffer tube (to take up the pre load on the springs) which also made a positive difference depending upon load and the spring rating.  Bottom line is that I feel that the spring in the gun that was falling off in accuracy was loosing oomph, by going to a new heavier spring, the accuracy was right back to where it was.

The why??  I personally feel that by having a bit of a heavier spring you get a more consistent lockup of the bolt.  I can't prove it, but that would seem to be the logical reason.

 

Link to comment
Share on other sites

N

20 hours ago, billdozer said:

I believe it was matt martini that was having accuracy problems and they went away by changing the scs out for s standard setup.

Turns out it was a barrel issue but we did quite a bit of testing with the SCS spring rate & BCG's.  What we found out was that if you use a UL BCG and a light spring (white or black JP) accuracy was not as good as with the same BCG utilizing a heavier spring (green or yellow).  

Ultimately, going to a WOA 1/7 twist fixed his issues with the 77gr ammo.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...