UPDATE

I got my upper back from Del-Ton today.

I was told that the handguard cap behind the FSB was a Colt part, and was made to different specs than most other caps. He said they had a bunch of these caps come in, and they made some HGs hard to install due to the different sized indents in the sides of the caps.

They replaced the d-ring and handguard cap, now the YHM guards fit just fine. The turnaround time was incredible. I called the day after the upper arrived at Del-Ton to find out how long the repair would take, and they told me it was all boxed up and ready to ship back to me! Wow.

If I had any complaints, it would be that the pins on the FSB were quite rusty. The gastube pin, sling swivel and FSB pins each had a decent amount of rust around the heads. I scrubbed them with solvent, and it seemed to remove 99% of it, but you can still see traces of it remaining. I'm not sure why this happened.

I will test fire it tomorrow and make sure everything works.











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I just finished my LW build.

Upper:

16" 1:9 Wison Arms chromed barrel with a1 FH, KNS .034 front sight post and a YHM rear BUIS.

Lower:
Ameetec Arms with Ergo grip, KNS Anti-rotation pins (I ordered anti-walk pins, but these work just as well.)

Oh, and before anyone give me any shit for the KNS A/R pins, they were completely necessary. The hammer and trigger pins would walk halfway out of the receiver before the
mag was empty.

Quoted: I just finished my LW build. Upper: 16" 1:9 Wison Arms chromed barrel with a1 FH, KNS .034 front sight post and a YHM rear BUIS. Lower: Ameetec Arms with Ergo grip, KNS Anti-rotation pins (I ordered anti-walk pins, but these work just as well.) Oh, and before anyone give me any shit for the KNS A/R pins, they were completely necessary. The hammer and trigger pins would walk halfway out of the receiver before the mag was empty. i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1302.jpg i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1304.jpg i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1306.jpg Here are the pics of the delta ring and handguard fitting problem that I posted about a while ago. The CAR HGs barely fit under the ring, leading me to believe it's set forward a bit too much. The only reason they fit at all, is that they're plastic and have some flex to them. When I try to install my YHM 4-rail handguards, they will not fit at ALL. In the photos I have the d-ring bottomed out against the receiver, and they STILL won't fit. The HGs need to move a tiny amount forward for the barrel nut's teeth to engage the groove in the HGs.   i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1285.jpg i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1287.jpg In these pics, you can see how the d-ring sits without any HGs installed. It appears to be positioned farther forward than my other rifles. The question is, how do I fix this? Do I have to get a receiver block clamp and tighten the nut down a few notches? The d-ring spins freely on the nut, so that can't be adjusted, as far as I know. i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1292.jpg i51.photobucket.com/albums/f392/BiteyMcClaws/IMG_1293.jpg Any Ideas?

First, don't apologize for using KNS pins.  The only person that can't stand them is markm.  I think more people will give you hell for having an Ameetec Arms reciever after the crap they pulled with the AR45.

Second, your delta assembly looks WAY OFF.  I would remove the barrel and look at the way you assembled it.

Quoted: First, don't apologize for using KNS pins.  The only person that can't stand them is markm.  I think more people will give you hell for having an Ameetec Arms reciever after the crap they pulled with the AR45. Second, your delta assembly looks WAY OFF.  I would remove the barrel and look at the way you assembled it.

I bought the upper assembled from Del-Ton. It came this way. I wanted to see if it was something I could fix myself, as I don't want to be down a rifle for however long it would take them to fix it.

I also got the Ameetec receiver WAY before all the AR45 shit blew up, so as far as I knew at the time, they were good-to-go.

Bump for suggestions.

If it's an assembled upper, I would send it back.

Your other options are:

1. Remove/Reinstall the barrel to see if the nut seats deeper on the receiver threads.
2. Replace the Barrel Nut/Delta Assembly.

Replacing the Assembly is going to require removing the FSB. This can be a PITA, so again, I would suggest sending it back vs. taking the risk of jacking up a new upper.

I don't see what Del-Ton has to do with this. You bought an accessory for an upper. I think they would be justified in charging you labor for this fitting. That's just me and now I'm off the AR15 accesory soapbox not necessarily directed at the OP.

If the HGs need to move forward a "tiny bit" get out your files and remove that amount from the front of the HGs, you wont see this as it will be inside the HG cap.

After doing this - if the HGs will bottom out against the rim of the HG cap before they move forward enough to lock in the back try removing a "tiny bit" of material from the channel in the rear of the HGs, the channel that engages the BN teeth.

If that doesn't work file a few thousandths off the front of the BN itself. Get it on there and go shooting this weekend.


good luck

Quoted: I don't see what Del-Ton has to do with this. You bought an accessory for an upper.

HUH?

If the guards are "in-spec" and the upper is "out of spec." how is that NOT the responsibility of the builder (Del-Ton).?

Quoted: I don't see what Del-Ton has to do with this. You bought an accessory for an upper. I think they would be justified in charging you labor for this fitting. That's just me and now I'm off the AR15 accesory soapbox not necessarily directed at the OP. If the HGs need to move forward a "tiny bit" get out your files and remove that amount from the front of the HGs, you wont see this as it will be inside the HG cap. After doing this - if the HGs will bottom out against the rim of the HG cap before they move forward enough to lock in the back try removing a "tiny bit" of material from the channel in the rear of the HGs, the channel that engages the BN teeth. If that doesn't work file a few thousandths off the front of the BN itself. Get it on there and go shooting this weekend. good luck

I had the HGs on another 16" M4 Del-Ton upper than I sold to fund this one. The d-ring is also notably farther forward than my 20" A4 Del-Ton rifle that I compared it to.

The HGs fit fine on the last upper. I am using them as a yardstick to say "ok, this upper may not be assembled properly."

I'd rather not file down the HGs if the problem is with the upper.

Quoted: My concern would be that the barrel nut is not on properly.

That occurred to me as well. Would that cause malfunctions? I'f shot a few hundred rounds through it since I got it, and haven't had one jam or malf at all.

I think it's going back to DT this week.

bump for update, first post.

bump for days

Now get us a range report