Polish AR feed ramp

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  • Bmash

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    Dec 23, 2013
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    I have a 6.5 Grendel and I believe the feed ramp needs to be worked or at least polished. On a couple of bullets (129ABLR and 105 MKZ) the tips are damaged and on the MKZ it often won’t feed.
    Recommendation on somebody local to do this? I assume this is not a do it yourself job…
     

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    shrxfn

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    Looks like there is a lip between the lip on the extension and the upper. It may need to be blended and not just polished.
     

    John_

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    Looks like there is a lip between the lip on the extension and the upper. It may need to be blended and not just polished.
    Agreed. Blend with a dremel and an appropriate bit. There is a slight ledge or misalignment between two upper receiver feed ramps and the barrel extension. Any decent gunsmith can make short work this. I have done a couple of my own weapons to blend and smooth. His doesn't need much, probably just catching the projectile tip on the way into the chamber from the magazine.
     

    Mitch Dufour

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    It does appear to be an issue with the two feed ramps extending a bit to far, but I have to ask. How many different magazines have you tried with this gun? When I have feed issues with any gun, I always try to rule out magazines first.
     

    Bmash

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    Thanks guys. I have tried 2 different mags. One wouldn’t feed at all and the other worked for about 30 rounds with this bullet. BTW Hornady ELD-M ammo has no issue at all, but the profile is a lot different than the MKZ 105. Looking at the picture I think the condition has worsened as it impacted numerous times.
    What “appropriate“ bit would you recommend. I am thinking go slow, use one bit to remove/blend and then finish with a very fine bit to polish.
    Thanks again!
     

    John_

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    I would use a cylindrical abrasive cutter, sort of cone shaped. One that fits the profile of the receiver feed ramp, or better slightly larger. This is what you want to do, you want to cut the barrel extension not the receiver feed ramps. The rec feed ramps are AL, the barrel extension in steel. And judging from ur pics above, its not going to take much. Invariably you will touch/slightly cut the feed ramp too, but hopefully in the latter stage of the operation. A steady hand and a receiver block in a bench vice will help big time. Or you can clamp the receiver/upper assembly in a bench vice lightly, and wrap it before hand in an old towel. Don't want to clamp it hard enough to damage the upper receiver, nor the ext finish. I have the Dremel cable extension, its a pencil device holding the bit. Works great, I use it mainly for engravings.

    Obviously you just want to remove that raised edge of the barrel extension compared to the receiver feed ramps. Here is a link to the dremel cable hand held tool → tool
     

    John_

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    Here are the abrasive bits in a kit I recommend. But you could also use an appropriate sized dremel cylindrical metal cutter. I just favor the abrasive conical shaped stone type for this sort of task. dremel stone type bit

    Home Depot sells the bits/cutters/polishers individually. Least my local HD does. Cheaper and you get exactly what you want, not a collection.

    Dremels spin at like 20,000 rpm, unless you have a variable speed unit which I also have. My original dremel tool (fixed speed) I purchased prob 25 or 30 years ago. Still have it and use it regularly.

    The high speed won't hurt you, you just have to have a steady hand, really good lighting, plan your access with the tool, and the receiver fixed in a vice.
     

    John_

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    @Bmash if you don't already own a dremel, it would prob be cheaper to just take the upper to a gunsmith and have him smooth the problem out. A good smith will make very short work of this, and if it costs you $50, cheaper than purchasing the dremel, bit, and hand held cable extension. And you def need a solid vice and excellent lighting to do this properly imo.
     

    Bmash

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    John, thank you for taking the time to help! I really appreciate it!
    I do have a variable speed Dremel and several bits, vise, barrel block, and everything for barrel removal. (SLR handguard/barrel nut so I had to remove gas block and muzzle device to get the SLR tool on barrel nut.)
    IF I had a local good gunsmith that would have time to do this as a walk in then I would. I need it for grandkids hunting next week so I don’t want to leave it somewhere. I have used a gunsmith in Gonzoles but I REALLY don’t want to drive around Baton Rouge Christmas week.
    The smith I use to build bolt guns, change and thread barrels, etc is a friend that lives south of Houston.
     

    John_

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    John, thank you for taking the time to help! I really appreciate it!
    I do have a variable speed Dremel and several bits, vise, barrel block, and everything for barrel removal. (SLR handguard/barrel nut so I had to remove gas block and muzzle device to get the SLR tool on barrel nut.)
    IF I had a local good gunsmith that would have time to do this as a walk in then I would. I need it for grandkids hunting next week so I don’t want to leave it somewhere. I have used a gunsmith in Gonzoles but I REALLY don’t want to drive around Baton Rouge Christmas week.
    The smith I use to build bolt guns, change and thread barrels, etc is a friend that lives south of Houston.

    well you have most everything needed then I'd give it a shot. I was thinking more on this and a skilled gunsmith might do it with a simple rat tailed file and call it a day. By hand. Just to note, I was not advocating disassembly to do this job, removing the barrel/barrel extension from the receiver. If you do it with the dremel, go after it @ high speed. It cuts better and will have less inclination to walk on you imo. Just plan your attack and work slowly at it. Let us know how it all works out for you.
     

    topgunz1

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    John, thank you for taking the time to help! I really appreciate it!
    I do have a variable speed Dremel and several bits, vise, barrel block, and everything for barrel removal. (SLR handguard/barrel nut so I had to remove gas block and muzzle device to get the SLR tool on barrel nut.)
    IF I had a local good gunsmith that would have time to do this as a walk in then I would. I need it for grandkids hunting next week so I don’t want to leave it somewhere. I have used a gunsmith in Gonzoles but I REALLY don’t want to drive around Baton Rouge Christmas week.
    The smith I use to build bolt guns, change and thread barrels, etc is a friend that lives south of Houston.


    Jesse the manager at Bayou Pawn in Zachary is a fair hand with guns, their stores have been my gun source for many years now. It looks like you can probably smooth it out with a dremel, but if you wanted someone else to take a look he may have some ideas.
     

    Magdump

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    I realize not everyone keeps the set of smithing tools that I do, but I’d remove the barrel. I’ve done a couple of these over the years and find it way easier to do a good clean job and keep the anodizing intact. Very easy to refit and check progress on the heavy removal and once you’re there just polish before reseating the barrel.
     

    Bmash

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    Using the dremel I took a little off at a time, reinstalled barrel to check progress, and repeat. I then cycled a couple of magazines with no feed issue.

    Thoughts on polishing?
    I couldn’t find a polishing bit at Home Depot so I plan to polish with a patch on a mop in a hand help battery operated drill. Should I use some very fine sand paper first?
    And then J&B bore cleaning compound and finish with Flitz?
     

    Magdump

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    Using the dremel I took a little off at a time, reinstalled barrel to check progress, and repeat. I then cycled a couple of magazines with no feed issue.

    Thoughts on polishing?
    I couldn’t find a polishing bit at Home Depot so I plan to polish with a patch on a mop in a hand help battery operated drill. Should I use some very fine sand paper first?
    And then J&B bore cleaning compound and finish with Flitz?
    I’d wind a strip of auto sandpaper around a rod that will fit with a piece of tape on the end and use a drill. Let the clockwise rotation of the drill wind the few inches of abrasive to hold it then work the ramps. Maybe 400 to start and move up to 1000 then rouge then flitz.
     

    shrxfn

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    Why not just use your dremel with a felt tip and some abrasive paste should make quick work of it?

    Also if its feeding fine I am not even sure I would polish unless there are rough spots if its working no need for it to be mirror polished in my mind.
     

    Bmash

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    Why not just use your dremel with a felt tip and some abrasive paste should make quick work of it?

    Also if its feeding fine I am not even sure I would polish unless there are rough spots if its working no need for it to be mirror polished in my mind.
    Yesterday I was seeing some some brass from the case or bullet in the bolt lock up area, so I figured a quick polish and smoothing of a few areas would help, and I don’t have a felt tip. (I need to order some dremel bits since Home Depot is terrible!) I used a small wood dowel that would fit in the ramp area with 400 and then 1000 grit auto sand paper as suggested above, followed by some Flitz. Cycled with the charging handle and saw no brass or scratches, soooo all done but test firing - unless I messed up something!
    thanks for the help guys!
     

    shrxfn

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    Not sure what you have in your area but Walmart and HF sell dremel bits as well. Gald to hear you got it sorted out and were able to do it yourself.
     
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