SBR failures to feed

[bamashooter]

Thanks! I can do most work on my ARs myself, but anything involving a Dremel may be something I let a professional handle just to be safe. I do appreciate the info though.

Though they come in assorted grades of coarseness, Cratex or any good quality substitute are very forgiving. Especially on steel.

[Circle_10]

Though they come in assorted grades of coarseness, Cratex or any good quality substitute are very forgiving. Especially on steel.

So if one were going to polish the feedramps to make sure they interface well with the receiver cuts, it's seems like you'd want to do the polishing with the barrel in place, to ensure both surfaces are polished to the same degree and ending up mostly flush with each other, however wouldn't that run the risk of stripping the anodizing off the receiver cuts? I know late 90s and early 2000s Colt 6520s sometimes had bare aluminum receiver cuts that were added post- anodizing (that's what mine has) so it isn't a huge issue but is technically inferior to anodized cuts.
So is removing the barrel the proper way to do it?

[MistWolf]

I don't know if you should remove the barrel before polishing or not. But steel is tougher than aluminum and the polisher will cut through the aluminum faster.

[Circle_10]

I don't know if you should remove the barrel before polishing or not. But steel is tougher than aluminum and the polisher will cut through the aluminum faster.

Yeah.
This sounds like it's crossing the line from assembly to actual "gunsmithing" and I should probably stay in my lane. I may stick the barrel in a different upper (I have an M4 ramped A1 upper, as well as a second ramped C7 on order) initially and see if the barrel mates up better. If I go the polishing route I think I'll bring it to the guy who engraved my lower, he does quite a bit of AR work.

[gaijin]

Remove the barrel if you polish the feed ramps.

[Iraqgunz]

Not knowing your skill level, it's hard to say. I have done plenty of touch up like this with barrels installed. It's probably about 30-45 seconds per ramp.

So if one were going to polish the feedramps to make sure they interface well with the receiver cuts, it's seems like you'd want to do the polishing with the barrel in place, to ensure both surfaces are polished to the same degree and ending up mostly flush with each other, however wouldn't that run the risk of stripping the anodizing off the receiver cuts? I know late 90s and early 2000s Colt 6520s sometimes had bare aluminum receiver cuts that were added post- anodizing (that's what mine has) so it isn't a huge issue but is technically inferior to anodized cuts.
So is removing the barrel the proper way to do it?

[Circle_10]

Not knowing your skill level, it's hard to say. I have done plenty of touch up like this with barrels installed. It's probably about 30-45 seconds per ramp.

It's something I'd probably want to practice first before trying it on my SBR barrel.
I do have a barrel in my "junk upper" (slapped together for use with garbage ammo and malfunction clearance practice) that has legitimately very out of spec feedramps that might serve as a good candidate to practice on.

[26 Inf]

It's something I'd probably want to practice first before trying it on my SBR barrel.
I do have a barrel in my "junk upper" (slapped together for use with garbage ammo and malfunction clearance practice) that has legitimately very out of spec feedramps that might serve as a good candidate to practice on.

Unless you can find some place that sells CRATEX or other rubberized polishing/grinding tips in small quantities, setting yourself up to do this gets kind of pricey.

Here's the place I use: https://www.moldshoptools.com/catalo...ategory_id=245

I'm probably different than some folks, I have XFine, Fine, Med, and Coarse, but use Med and XFine most.

I also use their felt bobs with polishing or lapping compound: https://www.moldshoptools.com/catalo...category_id=20

I also prefer a flexible shaft tool, versus a traditional hold in your hand rotary tool. The one I have at home is an el cheapo Blue Hawk from Lowes. It has a rotary dial to control speed and overall works lights out for the price I paid. It's worked well for the several years I've had it.

[Iraqgunz]

Trust me when I tell you, it's not very complicated at all.

It's something I'd probably want to practice first before trying it on my SBR barrel.
I do have a barrel in my "junk upper" (slapped together for use with garbage ammo and malfunction clearance practice) that has legitimately very out of spec feedramps that might serve as a good candidate to practice on.

[Circle_10]

Well I have been needing an excuse to buy a new Dremel anyway.