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Sniperboy

JHP reliability on PCCs? Share your build?

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Without going into a long winded story : ) I use JHPs and my JP complete GMR13 rifle (two different complete uppers) have always been reliable with JHPs.  Being bored with such reliability I opted to build a backup rifle with a QC10 Glock lower.  Suffice to say I am not so bored now. : p  I did try the search and spent a while reading through old threads to get a clue before posting, so please be gentle.

 

I want to use a 33 Glock big stick magazine for this build.  I know from experience that Glock 26 magazines are mystically reliable with JHPs w/ JP lowers or others.

 

I have gotten the QC10 lower to work with a complete JP upper but with the big stick magazines I get jams (the bullet makes it into the chamber but is crooked and is out of battery maybe 1/5 times).  Taccom uppers won't even feed the 1st round and gets stuck just above the extreme feed ramp.

 

Do you guys who can run JHPs reliably mind sharing your build with me?

I use a Blitzkrieg w/ 308 carbine spring, and use the same mag reliably on my JP but it is finicky with my QC10 lower.  Hiperfire 24C trigger.

 

Edited by Sniperboy

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Qc10 upper and lower

icrw rail

the answer comp

shooting innovations ramped barrel 14.5”

icrw bolt

ar gold 308 trigger 

blitzkreig hd5150, 2.6oz weight jp carbine spring 

or mbx buffer blue internal and yellow sprinco with shortest spacer

cmmg lpk

magpul sl stock 

bcm buffer tube

lrbho is ground flush 

 

I only use Everglade v2 jhp 115gr, 4.6 gr wsf 1.12 oal and cci spp#500

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Thanks for sharing!  I use Precision Delta 115gr JHP.  OAL is 1.115"

I do have a spare QC10 stripped upper... I'll look up the barrel and I also wonder if upper receivers make a difference like lowers do (height of mag presentation and feed angle in lowers).

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I have 2 guns with QC10 uppers (side charging) and lowers (glock), a competition style PCC and more of a PDW style pistol,  and have never had a single issue with feeding. I don't have ramped barrels either. (BSF barrels)

I prefer JHPs to help keep comps cleaner. I also prefer 115gr on comp'd guns, because it just seems to work better, IMO. However, I have also shot 147gr federal HSTs (my defensive/carry ammo) with no issues.

Gun 1 (competition style PCC):

QC10 sidecharging glock receiver set
JP 9mm bolt
BSF 16" barrel
APA The Answer comp
TriggerTech Diamond Trigger
Coda Evolution 15" carbon fiber handguard
HD Blitzkrieg buffer with spacer/weight to short stroke

Gun 2 (PDW style pistol):

mostly the same, but with these changes:
BSF barrel is 8"
Brigand Arms 7" Atlas carbon fiber handguard
Odin Works 3 piece comp with the outer titanium sleeve
MBX buffer recoil system

I think everything else is the same. Oh, and I use reduced power ar15 springs, which maybe is uncommon compared to the heavier springs others use... but I like the way they cycle and it also makes the side chargers easier to use (can be really stiff with heavy springs).

I'd guess it's a problem with your lower, upper, or barrel. I have heard of some people needing to go to ramped barrels to solve feeding problems, but it's never been an issue for me with these barrels.

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Have you tried adjusting the OAL? I would try to shorten it some and see how that does. 

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Thanks to everyone who shared their feedback.

 

All signs so far seem to indicate that the common thread is the QC10 lower + upper.  Since I have a stripped upper handy I can try that with not much out of pocket.

The barrel suggestions are good too so I know what already works.

 

I will look into tweaking the ammo.  The 1.115" JHP dos work with my JP so I kind of think it's kind of like treating a symptom, not curing the issue.

I did try a 223 carbine spring and it performed the same as my 308 carbine spring.

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Mine had issues until I installed the Taccom ramp. ATI (NFA clone) lower, NFA side charging upper, barrel is from the ATI. 

 

Once i put the ramp in it started working great.

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Zero issues with MG JHP's, PD JHP's, Hornady XTP, Federal HST or CorBon DPX. I run full JP's though so like your initial setup, my guns just run. 

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QC10 gsf lowers with SI 14.5” ramped barrels and QC10 Bolts in both my guns.  All I shoot jhp and I have zero issues.

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Thanks for the feedback..  upon visual inspection I don't think the upper receiver makes a difference (compared my QC10 and generic JP upper). 

Another common link seems to be the use of shooting innovations ramped barrels - I'll look into that.  It seems like this ramp was TACCOM's original ramped design.

Edited by Sniperboy

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try a ETS mag

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Taccom ULW 5.25" complete upper …  QC 10 lower... HiperFire 24C trigger... Blitzkrieg Hyd. buffer standard... Springco red spring.. both PCC's has run 100% … using RN 124 gr plated bullets... 

 

 

Edited by cecil

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21 minutes ago, cecil said:

Taccom ULW 5.25" complete upper …  QC 10 lower... HiperFire 24C trigger... Blitzkrieg Hyd. buffer standard... Springco red spring.. both PCC's has run 100% … using RN 124 gr plated bullets... 

 

 

 

Have you tried your setup with JHP?

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yes... I experienced feeding problems using Precision Delta JHP 124 gr bullets in both my PCC's... adjusted the AOL from 1.08 up to 1.16 without any success...  when I shot some Everglades 124 RN plated bullets both PCC's ran 100%... I have tried 100 gr Berry's hollow base bullets as well as Berry's RN 115 gr plated bullets... they also ran 100% .. when I was having problems with JHP bullets.. I called Tim at Taccom.. he said some PCC''s run with JHP's some won't... so from now on.... I will only use round nose bullets in my PCC's

    However ..  I do run Precision Delta JHP bullets in all my Open major guns... they all run 100% ..

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Thanks for taking the time to share feedback.. this is a good data point. 

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My JP has ran fine with JHPs from the start but I had a PSA that was not reliable with them until I broke the sharp corner on the chamber and polished it up good.  It will run 100% with JHPs now also. 

That is one of the first things I would look at. 

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Triangle built QC10 with jp parts. Runs great with any profile 124 gr bullets. No issues. My other parts guns doesn't like jhp with sharp shoulders, but will run zero 125 gr jhp. It's a backup gun so I only feed it what it likes.

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The last two posts makes sense and completes more of the puzzle.  With my JP complete upper and the QC lower, there is a horizontal mark/nail sized nick on the middle of the brass during jams - I assume its from the round hanging up at the sharp bottom corner at the hole of the chamber (like a see saw) and the sharp corner of the bullet shape prolly gets stuck as it hits the top of the chamber.  This also is likely why a few guys with RN issues have scrape marks on the bullet tip.

 

JP solved this by seating/presenting the magazine higher and closer to the barrel with their lower.

 

I guess in this case you get what you pay for ($$$ JP lowers) if you want to shoot JHP.

 

The only other variable now it seems is the Shooting Innovations ramped barrel and I'll look into that if I build up my QC10, or just use round nose. : )

I'll be chumming the waters at my local range to see if anyone has an SI barreled upper I can try.  : ) I'd eventually like to build a 10" barrel with long cop or shroud.

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Another tangent.  My QC lower is 80% reliable in a JP upper, but will not even feed the first round in other brand uppers.  Part of me wonders now if the JP barrel has some benefit or if the JP bolt has some special design also.  Could be each part of the JP system has some individual secret or I'm just unlucky.  Lesson learned, you'd think by this stage in my life I'd've learned to leave boring & reliable good enough alone : ).

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PD 124gr JHP OAL 1.111, Everglades 124gr JHP RN oal 1.125, all feed no problem in FX-9 8".

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You could also try swapping out the 308 spring for a regular carbine spring. My NFA glock lower franken AR9 build did the same thing you mention your's did even with fmj rounds. Failures to feed rounds jammed half way into the chamber leaving a smile shaped dent from the bottom edge of the chamber.

 

The carbine spring has just a little less force trying to slam rounds into the chamber giving just enough time for the round to straighten itself out for a feed instead of a jam. My best guess anyway. It's something easy to try and all I know is it fixed it.

 

Spent brass would still have some scraping  from the bottom lip of the chamber but some polish and a dremel lessened that enough where it doesn't bother me, and I haven't had any failures to feed since with all ammo types.

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Thanks for the tips.  I will look up the FX-9.

As for the spring, I did try a 223 carbine spring instead of the 308 and it was the same result sadly.  I do appreciate the idea but it did not work for me.


I did buy a new barrel and will try my own build with a QC10 stripped upper I have in hand this weekend.  From eyeballing it I think the QC10 upper is dimensionaly the same as the standard JP upper receiver (or any upper for that matter) but am crossing my fingers.

Edited by Sniperboy

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