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

JP jumps on the short stroke bandwagon


Recommended Posts

  • Replies 304
  • Created
  • Last Reply

Top Posters In This Topic

Awesome thread so far guys. I am wondering has anyone tried the MBX short stroked?  Not much talk about the MBX system. I am currently using a PWS stock. Works great with 147 grain but 115 are quite jarring with the recoil. You really notice the jarring on your head when your cheek is against the stock. I am hoping to get a buffer system to make it even smoother and flatter. 

 

Thanks for any feedback. 

Link to comment
22 minutes ago, Nitro1 said:

Awesome thread so far guys. I am wondering has anyone tried the MBX short stroked?  Not much talk about the MBX system. I am currently using a PWS stock. Works great with 147 grain but 115 are quite jarring with the recoil. You really notice the jarring on your head when your cheek is against the stock. I am hoping to get a buffer system to make it even smoother and flatter. 

 

Thanks for any feedback. 

 

On my to-do list.  I have two (non-JP) uppers using Taccom upper receivers, one with the MBX barrel/brake and handguard, and the other with the Taccom tension barrel/brake.  Been running my JP GMR-13 for matches, and haven't had much chance yet to try the other uppers.

Link to comment
23 hours ago, Nitro1 said:

I might just order and do my own review. 

 

Looking forward to your take on the MBX system. 

 

I got the MBX Tuning/Rebuild Kit when I ordered the MBX Recoil Reduction System. The internal spring the buffer system comes with installed is the heaviest spring set up for major PF. At least I think it is for major PF as it just says "high power ammunition" - There are two other springs for "medium power ammunition" and "low power ammunition"

Link to comment
3 hours ago, Fo0 said:

 

I got the MBX Tuning/Rebuild Kit when I ordered the MBX Recoil Reduction System. The internal spring the buffer system comes with installed is the heaviest spring set up for major PF. At least I think it is for major PF as it just says "high power ammunition" - There are two other springs for "medium power ammunition" and "low power ammunition"

I did the same. I talked to BMX and they strongly recommended the tuning kit especially if running factory loads. 

Link to comment

Well got my MBX buffer kit in. Took it to the range to test it all out. Ended up not needed the tuning kit with the loads I plan to run but it was good to have and experiment with.  

 

So with the buffer kit in shooting 115 grain factory ammo it now feels like shooting 147 grain with the stock buffer.  Aka big reduction in recoil hit.  My biggest issue was 115 would jar my head and I would lose my optic and for steel challenge that is a problem. But with the kit I can comfortable shot 115 grain and 147 now has almost no recoil which is amazing.  147 will most likely be my chosen route but it is nice to know if I must shoot 115 I can with no more hard recoil. 

 

One crazy / scary thing did happen. I still can have my LRHO with the buffer kit. So I locked it back which is super tight by the way. I then loaded my mags and went to drop the bolt. When I did the gun discharged. Luckily I was pointed down range and all is good. But even the range office who was curious as hell about the kit saw it and went “what the hell”. Gun was on safe and finger way out of the trigger guard. I continued to experiment with this since and no issues.  My guess is since the spring was brand new and so tight it sent the bolt home so fast and hard compared to how it normally would it also forced the firing pin forward.   Very crazy. But all seems good now. 

 

Have a final steel eel challenge tournament tomorrow here in Michigan. Will report how it performs. 

 

Long post but I hope it helps. 

Link to comment

They actually usually touch the magazine follower...  But anything like that that serves no purpose should be removed...  In my opinion...  LRBHO usually stops working when you short stroke the bolt anyway...

 

In any event, you need to find out why your gun discharged and fix it...  Removing something that gets in the way and doesn't help is a good start.

 

Or, maybe you need to take it to a gunsmith.

Link to comment

Update for you all.  

 

I took tue gun in to my shop and had the gunsmith test the whole thing down and look at it all.  Everything looks perfect. I explained what happened and here is his expert knowledge and opinion.  The buffer kit was so strong and had so much force that when I let the bolt go into battery it was so strong and engaged so fast that the firing pin also slammed forward and caused the discharge. He explained that it is impossible unless the trigger broke, which it is not, for the hammer to engage and release when the gun is on “safe”. His advice which I took and did. Return the buffer kit and go with the JP short stroke system.  MBX was awesome and took it back with no question. I sent it back yesterday.  I will let you know the result when I get the new JP kit. I have the owner of my gun store doing me a solid and calling JP to have one custom made for my gun and it’s tolerances. 

Link to comment

Listen to Raylon, take the bolt catch out !

 

I have the Taccom3 buffer kit with the short stroke . As soon as I felt the pressure on the bolt with this set up, I took the bolt catch out! If I had the bolt catch in, I could lock the bolt back, but I would be afraid it would knock the barrel off if I let it slam home.

 

When you feel that much pressure against the bolt, instincts should tell you not to lock it back and let it go.

 

I completely disagree with your gunsmith. With the bolt under that much pressure and inertia, I could absolutely see the firing pin slamming forward and igniting a primer. Maybe not every time, but once is all it takes.

4 hours ago, Nitro1 said:

Update for you all.  

 

I took tue gun in to my shop and had the gunsmith test the whole thing down and look at it all.  Everything looks perfect. I explained what happened and here is his expert knowledge and opinion.  The buffer kit was so strong and had so much force that when I let the bolt go into battery it was so strong and engaged so fast that the firing pin also slammed forward and caused the discharge. He explained that it is impossible unless the trigger broke, which it is not, for the hammer to engage and release when the gun is on “safe”. His advice which I took and did. Return the buffer kit and go with the JP short stroke system.  MBX was awesome and took it back with no question. I sent it back yesterday.  I will let you know the result when I get the new JP kit. I have the owner of my gun store doing me a solid and calling JP to have one custom made for my gun and it’s tolerances. 

 

Edited by SJMPCC022
content
Link to comment
23 hours ago, Nitro1 said:

I will look into removing it. 

I saw your whole reply before you did your edit.

 

I may have misread your explanation, but it was confusing.

 

I took it as the gunsmith said the  bolt slamming causing the firing pin to strike the primer was impossible unless the trigger either was broken or broke as in breaks to fire a shot?

 

If he meant the same thing as I said of course I agree. I don't see what the trigger would have to do with it? When you cycle the bolt back, the hammer is locked back and ready to go. My point was the inertia could cause the round to go off without the hammer moving at all.

Link to comment
31 minutes ago, SJMPCC022 said:

I saw your whole reply before you did your edit.

 

I may have misread your explanation, but it was confusing.

 

I took it as the gunsmith said the  bolt slamming causing the firing pin to strike the primer was impossible unless the trigger either was broken or broke as in breaks to fire a shot?

 

If he meant the same thing as I said of course I agree. I don't see what the trigger would have to do with it? When you cycle the bolt back, the hammer is locked back and ready to go. My point was the inertia could cause the round to go off without the hammer moving at all.

I did not want to cause an arguement thus the edit. But yes the gun smith said the same as you. Aka the inertia could cause the discharge without the sear, hammer or trigger ever being involved. 

 

The owner of of my local shop talked to JP for me and they are making a buffer for my PCC and its tolerances. Should be in Friday. Will let you know how it works as it will be a short stroke system. 

Link to comment

Are you talking about the large outer spring or the internal spring inside the weight? The outside spring was yellow and the internal was red.  I also tried the green and blue springs for the internal as I got the tuning kit. Overall the red worked best for eliminating the recoil. 

Link to comment
16 hours ago, Nitro1 said:

I did not want to cause an arguement thus the edit. But yes the gun smith said the same as you. Aka the inertia could cause the discharge without the sear, hammer or trigger ever being involved. 

 

The owner of of my local shop talked to JP for me and they are making a buffer for my PCC and its tolerances. Should be in Friday. Will let you know how it works as it will be a short stroke system. 

 

49 minutes ago, lacivilian said:

Has anyone compared the JP SS kit vs the Taccom with SS kit?

I've never tried the JP system but I like my Taccom system much better since I added the SS kit. I purposely did it that way to get a real comparison,  I shot a few matches before the SS kit.

Link to comment
2 hours ago, lacivilian said:

Has anyone compared the JP SS kit vs the Taccom with SS kit?

 

So far I prefer the JP SS kit over the Taccom, but I need to do a lot more testing before I have anything close to a firm opinion.  Also, it may matter which upper you're using.

FWIW, the JP version requires either the JP bolt or a regular 9mm bolt with the weight removed.

Link to comment

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...