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Thread: 6.5 Grendel AR15 Feeding and cycling

  1. #1
    Boolit Master

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    6.5 Grendel AR15 Feeding and cycling

    Now that the chambering issues are solved its on to to other bugs with with this gun.

    It keeps failing to feed. It keeps jamming into the feed ramp. I tried PC bullets to see if that would help and I did polish the feed ramp a little bit. It did not help. Any thoughts on how to help? Do i need a harder bullets? I am using Magpul 10 round .223 mags. It only holds 5 rounds of the Grendel.

    Second gremlin is I tuned a great load today. Brought a tear of hapinnes and I hope it wasnt a fluke ( happens a lot to me, repeatsbility is what counts). Down side is it doesn't cycle the bolt reliably. It has a riffle buffer and buffer spring. Took about 2 more grains of Reloader 7 to cycle the bolt reliably. Group went up to 3 inchs at 100 yards. I am going to try a faster powder to build more pressure and keep the velocity in the 1650fps zone to see if that will help the cycling. I dont want to tinker with the gas port. I am not mechanicly inclined at all.

    For 150 dollar barrel it impressed me. Now just need to iron out the kinks.

    Attached are jammed bullet, pick of the bullet nose, and the 100 yard target of the group that wouldnt cycle.

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  2. #2
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    Magazines made for the Grendel or 7.62X39 have a different follower than ones made for the 5.56 Nato cartridge. Swapping out the followers or getting a new 6.5 Grendel magazine may help with the feeding issue. It is important that the cartridge be held in the correct position to feed reliably.

  3. #3
    Boolit Buddy KMac's Avatar
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    Like Curator said, get some 6.5 Grendel specific magazines.
    I like E-Lander 17 round magazines for the 6.5 Grendel.
    https://www.larue.com/category/parts...s/6-5-grendel/
    These seem to work pretty well also from what I have heard:
    https://www.midwayusa.com/product/22...ss-steel-black
    Also you may need to de-edge, blend and polish the feed ramp on the barrel extension. Looks like you still have some sharp edges in the picture that may be contributing to the failure. Some of the guys refer to doing a "meltdown" on the barrel extension.
    But start with a proper magazine.
    A good resource for the 6.5 grendel is http://www.65grendel.com/
    Last edited by KMac; 11-09-2018 at 10:43 AM.
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  4. #4
    Boolit Master

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    Thanks. I have been shooting the Grendel for a few years and didnt know the mags where different.

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  5. #5
    Boolit Grand Master Texas by God's Avatar
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    What barrel are you using?

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    Boolit Master

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    Midway Stoner brand stainless steel 1:8 twist, 24 inches long with m4 feed ramps. I made sure the upper receiver had m4 feed ramp also. Barrel made the gun heavy. More than happy with its accuracy. Playing 2400 and D060-1 to see if i can get it to cycle.

    I use a rifle length gas system and a rifle recoil tube, spring and buffer with the mag pul fixed rifle stock.

    https://www.midwayusa.com/product/10...tainless-steel
    Last edited by Rcmaveric; 11-09-2018 at 08:24 PM.
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  7. #7
    Boolit Grand Master Texas by God's Avatar
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    I was very pleased with a Stoner .300 BO on a recent AR buildsembly. Good to hear it wasn't a fluke.

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    Boolit Master

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    It had a bunch of good reviews. I am more than happy with the accuracy. I just need to get it working smoothly. I would definately buy it again. Twist is pretty fast though. Wish it was slower like the BW barrel.

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  9. #9
    Boolit Master

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    Researched alot and I came to realize I couldnt aford low mass bolt or a low mass riffle buffer weight. So I chose to open up the gas port. Faster powders were working as i had thought. While the built pressures they lacked the sustained pressures. I got it cycling and shooting good with H4895. Needs a tuning but I was happy with the first 5 shots.

    After drilling out the flash hole I sent 15 rounds of jacketed ammo down it to take away any burs. Those 15 rounds feed just fine from the magazine with a COL of 2.245. Cast bullets had the same problem of jamming.

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  10. #10
    Boolit Grand Master popper's Avatar
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    Nose is hitting the feed ramp lug. Is that a single stack mag? Pointy jacketed slide around it. Up the load to eliminate the vertical.
    Whatever!

  11. #11
    Boolit Master

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    Quote Originally Posted by popper View Post
    Nose is hitting the feed ramp lug. Is that a single stack mag? Pointy jacketed slide around it. Up the load to eliminate the vertical.
    Thanks poper. I just spent the rest of the day polishing and smoothing the feed ramps. I just happen to have a diamond file that fit. I noticed that the reciever feed ramps had a different angle than the barrel extension and that looks like what the bullets where catching on. Now there is a smooth transition from the feed ramp of the reciever to the barrel extension. I adjusted seating depth to the max that would chamber. I was abl to cycle a mag full of dummy rounds. So i hope this fixes it.

    It is a double stack magpul mag. 10 round .223. It holds 5 rounds of Grendel.

    Yeah i have a load test for the H4895. That was just the first group i touched off when the range called for a ceasefire due to closing.

    I was hesitant to take a file or drill to anything because I can't undo what is done. It appears to be helping though. I was holding my tongue right though it seams.


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  12. #12
    Boolit Grand Master popper's Avatar
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    Yes, receiver often doesn't fit m4 ramps so I used a dremel grinder on one BO upper. I also had to use the diamond file on the ramps them selves to reduce the middle lug size (& widen the ramps). They hit the receiver strip which bounces them into that middle lug and jam. It looks like only a single stack mag with the grendel which kinda forces the nose into that middle lug. Actually, DPMS has changed their bolt/extension pattern to really reduce that middle lug size. When I got McGown to build my BO barrel, I procured and sent a wide ramp extension to be used. My pistol barrel (KAK) came with the wide extension and it works well with the 041 (RD) style nose. I'm seeing more non-milspec extensions now as many are NOT just using 223 or 308 rnds.
    Whatever!

  13. #13
    Boolit Master
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    I bought an AR stoner stainless barrel, 223 wylde. Would not cycle, gas port had to be reamed a little. Mid length gas system, rifle stock and buffer.

    Those flat cast bullets probably do not like the feed ramp, yea fine for a nice pointed 5.56 bullet. Might need to open it some more, maybe even more like the single feed set up on a 450 or similar.

  14. #14
    Boolit Master

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    Its feeding and cycling just fine now. Thanks guys. I tried going up a grain on the load and it made the groups worse. I am happy with 18g loads might try .5g higher and see if that helps.

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  15. #15
    Boolit Buddy dimaprok's Avatar
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    I was reading older thread recently looking for some load info on my first AR15 in 7.62x40WT and came across comment by RU shooter about lightening buffer, check it out, it doesn't sound complicated, about halfway down the page. http://castboolits.gunloads.com/show...WT-A-few-snags

  16. #16
    Boolit Master

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    I took the buffer weight apart. It crossed my mind lightening it. My buffer comes in at 4.5 oz so it is all ready about an 1oz under standard weight. I have 4 steel weights and one aluminum spacer. It ctossed my mind to try and find some aluminum tubing. It cycles and works great now soni am not worried about anymore.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check