JP reduced mass BCG and SCS

[Tim K]

I started a thread that got lost asking about trying to adjust the recoil impulse on an AR by fooling with BCG mass, buffer mass, and spring rate. I got lots of excellent advise, and in the end opted for a JP low mass bolt carries and the JP SCS (silent captured spring system).

Forty five minutes on the phone with JP got me talked into the higher mass buffer (with three tungsten weights), a couple of steel weights to try, and the adjustable spring kit. I wasn't sure then exactly how to go about testing, and now even after the fact I have to admit it took some trial and error.

Fortunately, on the day I went to the range to work on it a good friend who owns two complete JP rifles was there to help me evaluate. He didn't know much more than I did about what changes to actually make, but he was able to evaluate the changes and tell me if they felt right or not. An hour of fiddling got me very close I think.

What a difference. I'd not shot a high end AR that had been optimized like this before so I didn't know what to expect. What I got was a rifle that feels very much like shooting a bolt gun. It's very soft shooting, and there is almost no sense of the bolt going back and forth. When the shot breaks it's just a quick pulse of recoil like a bolt rifle. I started down this road to try to improve my ability to spot my impacts. It turned out to be very effective. I did my testing right prior to shooting a monthly match. The month before I was spotting roughly 75% of my impacts. The more stable the position the easier it was to see the bullet hit. As the positions got screwier, it got progressively more difficult to see what was happening. With the new parts installed, I saw 40 out of 40 impacts including ten fired from unsupported prone.

It was expensive. I think I spent $525 or something, and I already had an adjustable gas block. For my money, it was absolutely worth it. If I had it to do over again, I'd call JP, talk to Dustin, and describe my setup. I'd let him tell me which buffer masses to use and skip buying extra weights. I'd definitely buy the spring pack. Had I been stuck with the stock spring, the gun would not be shooting nearly as well as it is (I tried it).

[Delfuego]

Tubb CS Flat spring and the Tubb CWS is $80!!! Glad it's working for you though.

[Tim K]

Peter, the BCG was the bulk of the dollars.

[davsel]

Can you do the same thing with a "regular mass" BCG and a lighter weight buffer?
It just seems to me that the buffer and BCG are always mated and moving together against spring pressure.
Does it matter which end of the pair the majority of the weight resides?
What am I missing?

[Delfuego]

the BCG was the bulk of the dollars.

JP does make some sexy stuff!

[Tim K]

I asked the same question of JP. They claim it matters, but the explanation was a little hazy. I don't know the truth.

[Tim K]

MarkCO, in the lost thread you linked me to another reduced mass BCG that had serrations for the forward assist. Mind linking again? I didn't save it.

[Spdu4ia]

I'm glad you got some good feedback from shooting because playing with it in the shop there was no way I could feel the difference. I did get to shoot Stew's on Friday and it was butter smooth.

If you had to do it over would you piece it together like you did or just buy a complete JP rifle setup ?

[esaabye]

what is the weight of the rifle you are running? What about the break?

[MarkCO]

MarkCO, in the lost thread you linked me to another reduced mass BCG that had serrations for the forward assist. Mind linking again? I didn't save it.

I am assuming you mean the VooDoo Tactical? Young's has a superlight as well.