Ok I am some what new to 9mm builds. Only ever built 2.

I recently built an 10.5" upper pistol using an PSA 9mm dedicated lower and a KAK shockwave buffer tube and an JP Capture spring buffer and a Spinta bolt with the weight removed.


My question is when I pull the charging handle back to look at the bolt to bolt stop gap. The gap is huge like 1/2 inch or more. Looks like to me the bolt is traveling to far rearward.
I am worried about shooting it because it may break off the bolt hold open on the last round.

Is that gap something to worry about ?
On my only other 9mm build  I am using a conventional 9mm buffer  and it has about an 1/16 bolt to bolt stop gap.

Put $1.75 worth of quarters in the bottom of the buffer tube.

you cant do the quarters thing with the jp spring.are you sure that the jp spring you have  is the 9mm version with 4 weights

Yes it's the 9mm version. And your right I can't do the quarter thing with the JP spring.

I am going to put the standard buffer in it tonight out of my other 9mm build and see what the spacing is....

Couldn't you just increase the length of the bumper on the SCS to shorten the travel?

I would think some polymer or even quarters with holes drilled in them and put behind the bumper would work.

Or, why can't you put a spacer in front of the SCS?  I believe the SCS instructions tell you what size spacer and what ID you need to do that.