JP-5 reviews/input

[Jerome Poiret]

5 hours ago, Bdh821 said:

It has SROs.  I dont know the mounts.  I'll try and find out

 

Thank you

[Nolan]

15 hours ago, Jerome Poiret said:

May I ask you what red dots are on the left gun ?
And what mounts are you using on both guns ? Especially the 45° ones.
Thank you.

 

The offset mount on the left gun looks like an Arisaka

https://arisakadefense.com/offset-optic-mount-combo/

 

The SRO mount looks like a Scalar Works

https://www.tacticallink.com/scalarworks-low-drag-optic-mount-for-the-trijicon-rmr-lower-third-cowitness.html

 

 

Nolan

[OliverLee]

Finally build completed for me and my daughter.

 

[DwightSchrute]

Lock piece question:  At the start of a stage during a match recently, I had what I believe was a case ejection failure after the first shot, causing a jam up from the next stripped round.  Fumbled attempts to get the bolt to close with the timer running caused more rounds to collect in the receiver, and by the time I got the gun fully cleared, the stage was destroyed and the match was lost.  I had switched to a 70 degree lock piece because it made recoil with my 124 grain 130 PF loads almost nonexistent, but would going back to the 80 degree lock piece make a repeat of this ejection problem less likely in future matches?

[GrumpyNO]

3 minutes ago, DwightSchrute said:

but would going back to the 80 degree lock piece make a repeat of this ejection problem less likely in future matches?

I would say yes. The 70 lock piece is designed for factory ammo. I just recently got my 70 and I'm using it with 124 grs ammo with around 142 PF. That works great. For downloaded 130 PF ammo, the 80 is recommended. Sure, you can go lower and get even less recoil, but you risk what you have experienced. In my opinion, tuning stuff to the limit is not worth it. One hiccup will cost you the stage in this game. So my recommendation is that you go back to the 80.

[Bdh821]

6 minutes ago, DwightSchrute said:

Lock piece question:  At the start of a stage during a match recently, I had what I believe was a case ejection failure after the first shot, causing a jam up from the next stripped round.  Fumbled attempts to get the bolt to close with the timer running caused more rounds to collect in the receiver, and by the time I got the gun fully cleared, the stage was destroyed and the match was lost.  I had switched to a 70 degree lock piece because it made recoil with my 124 grain 130 PF loads almost nonexistent, but would going back to the 80 degree lock piece make a repeat of this ejection problem less likely in future matches?

70 locker, stock buffer scs spring, and 130pf ammo is too much locker/spring to cycle it reliably. 

 

you may wanna put the 80 back in or buy a jp AR15 scs spring kit and start with the white spring 

[Bdh821]

This past week I switched to the 70 locker with JP SCS AR15 green spring. ~140pf 115s. So far I love it cuz I get way less muzzle dip than my previous setup of 80 locker with JP AR10 scs red spring 

[Darqusoull13]

1 hour ago, DwightSchrute said:

Lock piece question:  At the start of a stage during a match recently, I had what I believe was a case ejection failure after the first shot, causing a jam up from the next stripped round.  Fumbled attempts to get the bolt to close with the timer running caused more rounds to collect in the receiver, and by the time I got the gun fully cleared, the stage was destroyed and the match was lost.  I had switched to a 70 degree lock piece because it made recoil with my 124 grain 130 PF loads almost nonexistent, but would going back to the 80 degree lock piece make a repeat of this ejection problem less likely in future matches?

There's a bunch of good info already posted in this thread. I'd strongly recommend going back and looking at the information related to lock pieces and running at the edge of operation. 

Short answer, you should be using an 80 degree lock pieces with 124's at 130 PF. 

[DwightSchrute]

1 hour ago, GrumpyNO said:

I would say yes. The 70 lock piece is designed for factory ammo. I just recently got my 70 and I'm using it with 124 grs ammo with around 142 PF. That works great. For downloaded 130 PF ammo, the 80 is recommended. Sure, you can go lower and get even less recoil, but you risk what you have experienced. In my opinion, tuning stuff to the limit is not worth it. One hiccup will cost you the stage in this game. So my recommendation is that you go back to the 80.

Sage advice.  And thanks to everyone else, too.  I’ll put the 80 degree lock piece back in and see how it goes.

[mmchambers06]

I ran the original 80 degree lock with factory 115s for a few months. Just switched to a 70 degree lock for last week's match based on the conversations here.

 

Had flawless ejection & bolt hold open, and improved recoil impulse/bounce. I can't imagine pushing the functional limit any further for PF/recoil improvements... gun stays on target about like a .223 with a good comp.

[Darqusoull13]

2 hours ago, mmchambers06 said:

I ran the original 80 degree lock with factory 115s for a few months. Just switched to a 70 degree lock for last week's match based on the conversations here.

 

Had flawless ejection & bolt hold open, and improved recoil impulse/bounce. I can't imagine pushing the functional limit any further for PF/recoil improvements... gun stays on target about like a .223 with a good comp.

Pretty standard. Most factory 115's are in the 140 PF range. 

[sharko]

I shoot 115's at 130PF, I tried a 70 & 60 lock but went back to the 180. Both functioned except the 60 wouldn't lock back on empty. But I couldn't really tell the difference between them, maybe I'll try springs and weights next. 

[drone14k]

Picking up my jp-5 tomorrow. I have some 147gr fmj rounds with 3.5gr TG that chrono at 129PF out of my shadow 2. Can I shoot the same load in the JP or do I risk a squib?

[RangerTrace]

7 hours ago, drone14k said:

Picking up my jp-5 tomorrow. I have some 147gr fmj rounds with 3.5gr TG that chrono at 129PF out of my shadow 2. Can I shoot the same load in the JP or do I risk a squib?

It should be fine, but may not even be close to PF.  That was my experience with N320 and 147s.  They were 930ish out of my Sig and 800 out of the JP.  124s did not give me the same results.

[Bdh821]

15 hours ago, drone14k said:

Picking up my jp-5 tomorrow. I have some 147gr fmj rounds with 3.5gr TG that chrono at 129PF out of my shadow 2. Can I shoot the same load in the JP or do I risk a squib?

I'd suggest some 124s or 115s.  The recoil impulse for 147s in PCCs is too slow/clunky.  In my experience, 147s cause more dot bounce than ~140 PF 115s or 124s

[drone14k]

On 5/15/2023 at 2:52 PM, Bdh821 said:

I'd suggest some 124s or 115s.  The recoil impulse for 147s in PCCs is too slow/clunky.  In my experience, 147s cause more dot bounce than ~140 PF 115s or 124s

Shot the 147gr fmjs that were 129pf out of my shadow and it was alright. Then I shot some old 140pf coated that I had and it felt like a whole different gun. 0 dot movement.

Not sure I understand why there was such a big difference unless it’s just the comp. The 140pf was softer and flatter. Felt like shooting a 22. 129pf had about the same dot movement as 5.56 but less push into my chest. 

[Bdh821]

3 hours ago, drone14k said:

Shot the 147gr fmjs that were 129pf out of my shadow and it was alright. Then I shot some old 140pf coated that I had and it felt like a whole different gun. 0 dot movement.

Not sure I understand why there was such a big difference unless it’s just the comp. The 140pf was softer and flatter. Felt like shooting a 22. 129pf had about the same dot movement as 5.56 but less push into my chest. 

It’s easier to say “because science” 

[drone14k]

14 hours ago, Bdh821 said:

It’s easier to say “because science” 

I want to learn so I can figure out a new load though 

[GrumpyNO]

4 minutes ago, drone14k said:

I want to learn so I can figure out a new load though 

Well. How heavy are the bullets in your 140pf load? You are using quite heavy bullets in your 129 pf load. The main deciding factor of recoil is bullet weight. The more weight, the more recoil. That's the science part.

[drone14k]

18 minutes ago, GrumpyNO said:

Well. How heavy are the bullets in your 140pf load? You are using quite heavy bullets in your 129 pf load. The main deciding factor of recoil is bullet weight. The more weight, the more recoil. That's the science part.

Both are 147gr

 

140pf ammo is using sport pistol with coated 147gr bullets

 

129 pf ammo is using Titegroup with 147gr fmjs

Edited May 17, 2023 by drone14k

[GrumpyNO]

1 minute ago, drone14k said:

Both are 147gr

Then I can only guess that the higher pf load cycles faster and that puts the dot back where it was faster. So it seems like less movement, but in reality it just settles faster. 

[drone14k]

2 minutes ago, GrumpyNO said:

Then I can only guess that the higher pf load cycles faster and that puts the dot back where it was faster. So it seems like less movement, but in reality it just settles faster. 

Edited my last post to include the types of bullets and powder used in each.

 

What’s weird is that it actually feels softer. Like going from shooting a plastic handgun to a 50oz steel gun

Edited May 17, 2023 by drone14k

[drone14k]

I wonder if it’s coated bullets vs fmjs? I can’t imagine Titegroup would make that big of a difference over sport pistol.

[Boomstick303]

1 minute ago, drone14k said:

I wonder if it’s coated bullets vs fmjs?

 

Off the clock when I am paying attention specifically for felt recoil, I have noted a slightly softer recoil impulse for coated ammo vs Jacketed bullets for ammo that has the same or similar PF and same bullet weight.  I am sure some of it has to do with, I load my Coated 0.1 gr of powder for the coated for the same PF for Jacketed ammo of the same bullet weight.  I think some of it has to do with the drag of the coated bullet vs jacketed bullets.  This is only a theory and I have not real world data to prove this out.  I do find the impulse and dot movement a little better with coated vs jacketed, but I cannot stand the lead buildup when using coated bullets in my PCC.

 

These are my personal observations.  Some may agree some may not.  

 

I do not note any of this on the clock.  Therefore I do not care.  

 

[Darqusoull13]

2 hours ago, drone14k said:

Both are 147gr

 

140pf ammo is using sport pistol with coated 147gr bullets

 

129 pf ammo is using Titegroup with 147gr fmjs

Using different powders, bullets and different charge weights is too many variables to compare. 

If you like how the Sport Pistol load shoots, go for it. I would avoid coated bullets in the comp but that's another discussion.