Q around M4 ramps

in DIY builds often we buy non-matched parts, meaning from a variety of vendors relying on manufacturing processes so the parts work together (maybe). many times the specs say they should match, like a "M4" barrel with a "M4" upper.

anyone do ramp polishing after attaching barrel?

Not needed.

Yes I have done it.  My buddy (works for Las Vegas Metro PD) had an issued weapon and the barrel and upper were not matched up very well.  We did some dremel work to the M4 ramps to match and polish them up.  It greatly improved the feeding and function of his rifle.

So.....while DangerDan may say its not needed.....sometimes it is.  

Feed ramp polishing is not needed. Some shops will try to sell you feed ramp polishing as a boutique item to make a few bucks. If a factory gun has misaligned ramps it's an error. And I have seen some pretty ugly ramp line up. What I do personally, to avoid this is I examine the upper and extension during assembly and if it doesn't line up correctly I use a different upper until I find one that lines up correctly. One of the minor pains of building AR's. All AR parts do not work in all AR rifles. -W

so, my Q is not about a barrel/upper from same maker, these are usually matched well. i just mean like a RR upper with a GreenMountain barrel (different vendors). the M4 cuts may align real close, but a light polish to mirror will smooth it out, etc. i did feed ramp smoothing and mirror polishing on my 1911-a1 and the action was a tad smoother.

just wondering if anyone does this, or are you inspecting the match-up, or just doing assemble & go?

No. a person certainly does not want to remove any of the hardcoat anodizing.

I am in the camp of NOT NEEDED..

Vince

Hi All just my 2 cents if the miss match is in the clocking barrel to
upper you can always open up the slot on the upper in the direction it
needs to be and hold it


in the right clocking when you tighten the b
nut , ya i know you can fill the gap with a cut down shim stock to make
it solid again.





and i agree with PFC ya don't want to remove the hard coat on the upper if you can avoid it.





if the miss match is a lip from upper to lower ( bigger cut outs on the barrel ) you should be fine nothing for the tip of the bullet to hag up on .


but if the lip is the other way ya i would polish the barrel ramps lower then the upper ramps.





is the upper a m4 ?? is the barrel m4 ??





If it was me before i do anything i'd find out what , witch part is off and if it's not manufactured right out of spec i'd just send it back and have'm replace it.



now I'm no expert in any of this only built 2 so far and both have miss matching but in the right way cut outs on the barrel just a bit bigger so i didn't touch them

no need to.
lock load live free






 

Unless you're experiencing FTF's, I'd say leave it alone.

It just depends. I had issues with ftf with an lmt upper and sent it back to lmt. They polished the feed ramps and sent it back. Worked great after that.

did the upper ramps have any hard coating, and if so did they just polish the coating, or did they need to re-coat it?
a simple polish (no metal removal) will make things move easier (as i found with my 1911 45), but the ramp was not hard coated.

They did not recoat it. It was just shiny metal with a very smooth ramp. Very similar to a polish job on a 1911.

I've done it with several AR'S and nothing has happened. Did they need it...dunno, does it help anything...dunno but it didn't hurt anything either. There's a fine line between polishing and grinding away metal. Once you cross it, it's done.

like with most fitments the pieces are not likely to be aligned 100% as desired, especially when the parts come from varying makers. i suspect a polishing is all that is needed 98% of the time to 1) blend and minor differences, and 2) makes it smoother (less friction) for sliding over.

this would be my 1st ar15/556 build so i will get to witness any issues and deal with them, but certainly not my 1st rodeo with blending and polishing.