The JR Carbine Thread
- Thread starter Konrad
- Start date
ThxNah I ordered the handle from sfrc and the front sight from true north arms! I think the front sight was like $30 and I forget how much the handle was. It's NCstar
I'd like some input from any 9mm JR owners out there regarding bullet weight vs accuracy.
I have been shooting at 100m with all different types of bullet weights and brands trying to find which combo runs the best and is most accurate over all. I own 2 9mm JRs so I am able to compare the same round in a different firearm which is fun for my own curiosity.
Originally I started out only shooting 115gr FMJ Blazer Brass and it produced acceptable results at 100m of 4-6" extreme spread groups. I don't expect bolt action, center fire type accuracy out of the 18" carbine barrel, but at 100m I did want to tighten things up if possible.
Cabela's here in MB has a damn good selection of 9mm ammo at the moment so I went and bought a bunch of different loadings and brands. Picked up 115gr, 124gr and 147gr in any brand they had.
I have tested with both JRs both sporting 2-7x Vortex scopes so the playing field was even with regards to optics.
115gr was the least accurate on average grouping 4-7" groups at 100m with the exception of Winchester white box 115gr. They were the most accurate putting a 5 shots into a 3" group with 4 out of 5 being within 1.5" extreme spread. I was very impressed with the result.
The 124gr FMJ produced the most accurate results on average grouping 3-4" extreme spread groups. The best of the bunch was Remington UMC 124gr surprisingly. Put a 5 shot group inside of 3" at 100m. Again, it was a night and day difference from the 115gr ammo. Recoil also felt more controlled and linear.
147gr American Eagle shot a 5" group consistently which still beat out 115gr on average.
What type of ammo have you had luck with in your 9mm JR? What type of accuracy do you typically see at 100m? Any input is appreciated!
I have been shooting at 100m with all different types of bullet weights and brands trying to find which combo runs the best and is most accurate over all. I own 2 9mm JRs so I am able to compare the same round in a different firearm which is fun for my own curiosity.
Originally I started out only shooting 115gr FMJ Blazer Brass and it produced acceptable results at 100m of 4-6" extreme spread groups. I don't expect bolt action, center fire type accuracy out of the 18" carbine barrel, but at 100m I did want to tighten things up if possible.
Cabela's here in MB has a damn good selection of 9mm ammo at the moment so I went and bought a bunch of different loadings and brands. Picked up 115gr, 124gr and 147gr in any brand they had.
I have tested with both JRs both sporting 2-7x Vortex scopes so the playing field was even with regards to optics.
115gr was the least accurate on average grouping 4-7" groups at 100m with the exception of Winchester white box 115gr. They were the most accurate putting a 5 shots into a 3" group with 4 out of 5 being within 1.5" extreme spread. I was very impressed with the result.
The 124gr FMJ produced the most accurate results on average grouping 3-4" extreme spread groups. The best of the bunch was Remington UMC 124gr surprisingly. Put a 5 shot group inside of 3" at 100m. Again, it was a night and day difference from the 115gr ammo. Recoil also felt more controlled and linear.
147gr American Eagle shot a 5" group consistently which still beat out 115gr on average.
What type of ammo have you had luck with in your 9mm JR? What type of accuracy do you typically see at 100m? Any input is appreciated!
I have put the basic upgrades to my GenI JR in 45ACP.
1.) new super heavy buffer weight
2.) new tapered rubber bumper and nylon spacer
3.) new spring with 3 coils cut off.
The rifle immediately began flawlessly operating after these mods.
I havent had a single failure since!
I was working up loads for my JR, and as I approached max charges in CFE pistol, and Unique (230 grain Campro bullet), the groups kept shrinking! By the time I was finished, groups at 50 yards were in the 1" relm, and 100 yard groups were in the 2-3" range or better! I was amazed!
Th average velocity is around 1086fps. I have shot about 500 of this load so far, and it keeps chugging away smooth and consistant!
1.) new super heavy buffer weight
2.) new tapered rubber bumper and nylon spacer
3.) new spring with 3 coils cut off.
The rifle immediately began flawlessly operating after these mods.
I havent had a single failure since!
I was working up loads for my JR, and as I approached max charges in CFE pistol, and Unique (230 grain Campro bullet), the groups kept shrinking! By the time I was finished, groups at 50 yards were in the 1" relm, and 100 yard groups were in the 2-3" range or better! I was amazed!
Th average velocity is around 1086fps. I have shot about 500 of this load so far, and it keeps chugging away smooth and consistant!
a few questions....
I picked up a second hand JR in 45. It's got the extended buffer tube, rubber bumper, buffer weight, spacer, and the bolt is marked as a MKII.
It seems to short stroke about every fifth round. It'll pick up a new cartridge and feed it into the chamber but not set the trigger. I've thoroughly cleaned and lubed everything but it still happens. What's the fix?
How do I know if the feed ramp has been upgraded? I don't know what an original looks like to compare to mine. Could someone post a picture of the upgraded ramp please?
It came with a 10 round Glock mag. I know nothing about glocks, are there better aftermarket mags or should I purchase more of these? Price don't matter I just want 5 or 6 mags that function reliably.
I picked up a second hand JR in 45. It's got the extended buffer tube, rubber bumper, buffer weight, spacer, and the bolt is marked as a MKII.
It seems to short stroke about every fifth round. It'll pick up a new cartridge and feed it into the chamber but not set the trigger. I've thoroughly cleaned and lubed everything but it still happens. What's the fix?
How do I know if the feed ramp has been upgraded? I don't know what an original looks like to compare to mine. Could someone post a picture of the upgraded ramp please?
It came with a 10 round Glock mag. I know nothing about glocks, are there better aftermarket mags or should I purchase more of these? Price don't matter I just want 5 or 6 mags that function reliably.
Could be as simple as the type of ammo, honestly. If you haven't already, try a different brand of ammo first. Next, take the trigger assembly out and try resetting by hand. If that doesn't help, you may have to lighten the spring tension by trimming it sightly until you can get the bolt to go back far enough to reset the trigger.
If you have an MKII bolt, your magwell is already the updated design.
Stick with factory Glock mags.
If you have an MKII bolt, your magwell is already the updated design.
Stick with factory Glock mags.
Thanks for the advice. I've tried 3 different types of ammo, I guess I'll try a few more.
I have only used 124 gr in mine and I am getting similar results at 100m with it as well. Usually 1-2" group at 50m (I am a horrible shot) and 3-4" at 100m with 124gr FMJ.
Cool, thanks for sharing your results. I have since started shooting 124gr Winchester white box ammo exclusively out of my 9mm and it has produced consistent 3" or better groups at 100m. Managed to get a best group of 5 shots in a 2.5" group at 100m. Pretty happy with the results for a PCC.
Now time to work on my 45 and see what it can do at 100m.
Now time to work on my 45 and see what it can do at 100m.
Mine needs to be cleaned every 2-3 hundred rounds of cruddy blazer buy it I used federal or better I can go much longer . All the gunk blazer makes the bolt starts to get stiff quicker and FTE. Once I use up the blazer never buying it again . For any of my guns
Very true the gun gets dirty real quick. I don't find too much diff Blazer or not. X-Metal is just as bad. Sumbro actually was cleaner for me. I bought it as takedown version then I replace it with a rail but I think I will switch back to takedown tube since it makes the cleaning much easier (plus the quick takedown kit is a must for me)
I never checked what gen mine was but I just bought it. I hope it's the newest lol. I have the quad rail one just like pictured above. I love it. I don't mind cleaning it either. I just keep the ring on the stock hand tight so I don't need the AR tool at the range if I need to clean it. It's blowback l so I knew it would be a dirty girl. I'm very impressed by the accuracy as well. 50 yads with a red dot benched I can land shots in a 1.5" group. I like it mostly because it's not that loud either. I can shoot it without ear protection (but I wear them anyways). I find it a little heavy though . But very solid. The bolt handle is a little small and not very ergonomic. But I'm an extremely picky person.
I love mostly that I can have the AR experience sorta without spending lots on ammo. And the best part is non restricted. I bought some 5/33 glock mags and it looks very tacticoool
Gen 2 or Gen 3 will be much more reliable than Gen 1. One range trip I put 700+ rounds down the tube without a hiccup or cleaning the thing. Get yourself some OEM Glock mags too. They work much better than the junk it comes with in Canada. Cheap mags are usually the reason the Gen2/3 don't run well.
Grab one, they're excellent PCCs.
I have a gen2 and pretty happy with it. The biggest bummer I had was that my TriggerTech TT-15 will not cycle reliably (short stroke and won't chamber next round) with it so I ended up fall back on the factory trigger group and everything ran just fine then (funny at the beginning I refuse to believe it was the TT-15 that caused all the problems). Other than that it runs very well and now passed the 3000 rds mark through it. I even used it to run 2Gun once.
If 45ACP gets cheaper and the conversion kit has a discount then I wouldn't mind converting this into 45 or run along with the 9mm version.
Btw I mainly run magpul Glock mags on it and they run just fine along with OEM Glock mag.
In fact the JR runs so fine it never crossed my mind that may be I should ever build a PPC AR15 when I already have AR doing 556, x39, 22lr and current considering doing 300. Nope, if I need a 9mm PPC I'll just grab the JR.
If 45ACP gets cheaper and the conversion kit has a discount then I wouldn't mind converting this into 45 or run along with the 9mm version.
Btw I mainly run magpul Glock mags on it and they run just fine along with OEM Glock mag.
In fact the JR runs so fine it never crossed my mind that may be I should ever build a PPC AR15 when I already have AR doing 556, x39, 22lr and current considering doing 300. Nope, if I need a 9mm PPC I'll just grab the JR.
