JP scs, low mass bcg, adj gas block.

[Cookieman8]

Just wanted to get a second opinion here if possible.

Heading to the range tomorrow to retune my 16" 3gun blaster with a JP scs, low mass bcg, and SA gas block.

I was under the impression that I should put the lightest spring (white 80%) in the standard JP scs and then tune the gas for my load.

If there are any others here that have tried this combo, some tips or tricks are appreciated. Thanks.

 

[TheOfficeT-Rex]

I did a similar set up, can't remember if I used the lightest spring or second lightest. I have an 18" rifle gas, but it runs like a champ. You'll be fine once you tune the gas.

 

[KZP]

I tried the 3 different spring weights and prefer the heaviest. The BCG cycles faster reducing lurch time making spotting hits easier.

Bring some tools with you, try different springs while you're out on the range.

 

[Earnhardt]

I tried the 3 different spring weights and prefer the heaviest. The BCG cycles faster reducing lurch time making spotting hits easier.

Bring some tools with you, try different springs while you're out on the range.

What’s lurch time?
Thanks

 

[KZP]

What’s lurch time?
Thanks

When lunch time overlaps with church service. Lurch time.

I'm trying to describe the duration of the rifle moving due to BCG being in motion, which makes it more difficult to see through the scope. IMO faster, snappy cycling of the BCG makes it easier to see hits on/near target because the overall movement stops sooner.

 

[Cookieman8]

I definitely plan on bringing everything in order to tune as best as I can. The springs are just a tad confusing for some reason. I'm guessing the springs are only there to tune how fast the bolt travels since I'm already controlling the gas with a adj gas block.

Whats the best method to test bolt speed? Is it simply a "feel" method?

 

[KZP]

I definitely plan on bringing everything in order to tune as best as I can. The springs are just a tad confusing for some reason. I'm guessing the springs are only there to tune how fast the bolt travels since I'm already controlling the gas with a adj gas block.

Whats the best method to test bolt speed? Is it simply a "feel" method?

I'd go with whatever makes you shoot better after testing. You may get better follow up shots with a different weight spring than I'm using.

 

[Cookieman8]

I'd go with whatever makes you shoot better after testing. You may get better follow up shots with a different weight spring than I'm using.

Got it. Thank you for the input, I'll let you guys know how it goes tomorrow evening.

 

[TonyTheTiger]

Whats the best method to test bolt speed? Is it simply a "feel" method?

For 3 gun I wouldn't worry so much about bolt speed or recoil feel, I'd try all the springs and shoot 5-10 pairs on paper at 25 yards with the fastest splits you can get. Do that with each spring with the gas tuned, on a separate target for each, being careful to start shooting the pair with a good hold on a centered aiming point.
Then measure the dispersion between the first and second shot in each pair and go with the tightest one. You need a minimum of 5 pairs to show how things are trending.

 

[Cookieman8]

Update : Went to the range today and got everything tuned in. Ended up with the white JP spring. Tried the other springs and I didn't see much difference between white and black spring. With that said, I "felt" a smidge quicker with the white. Maybe that's my mind but either way, gas and spring are all tuned in for my hoser loads. Much smoother with the low mass bolt, and jp scs with tuned gas. Thanks for the help fellas.

 

[TonyTheTiger]

How much tighter was the light spring vs. heavy spring?

 

[Cookieman8]

How much tighter was the light spring vs. heavy spring?

Tightness of groups? I didn't get a measurement. It was truly hard to tell. All springs held a solid group, the lightest spring just felt smoother. After I tuned my SJC brake, she was flat and smooth.

 

[Evintos]

Someone did a lot of testing on a Brian Enos forum (years ago) regarding low mass and the SCS with different spring rates regarding precision. Green and yellow outperformed white or black.