Please Help with AR 9mm Build Issue...

[johnsland8]

I just finished putting together a Palmetto State dedicated 9mm Colt Lower. When I tried to put it together with my upper, it would not go together. I finally was able to determine that the bolt is hitting on the base of the feed ramp of the lower, not allowing the upper and lower to come together all the way. I've used this upper and bolt with another lower utilizing a mag block insert so I feel like the feed ramp on the PSA lower just sits up too high, but I can't be sure.
I'm not sure what to do now? Do I remove material from the top of the feed ramp? Should I remove material from the bottom of the bolt? A little from each? Potential problems from either?
Any other ideas? I appreciate any help or insight anyone can provide...

Thank You!

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[AMProducts]

Ok, what's the make of your 9mm upper. There are kinda "two" standards for 9mm lowers, colt pattern and oly pattern, the big difference between the two is that the colt will feed from a double stack mag, and the oly pattern feeds from single-feed sten mags.

 

[iamrob]

I just finished putting together a Palmetto State dedicated 9mm Colt Lower. When I tried to put it together with my upper, it would not go together. I finally was able to determine that the bolt is hitting on the base of the feed ramp of the lower, not allowing the upper and lower to come together all the way. I've used this upper and bolt with another lower utilizing a mag block insert so I feel like the feed ramp on the PSA lower just sits up too high, but I can't be sure.
I'm not sure what to do now? Do I remove material from the top of the feed ramp? Should I remove material from the bottom of the bolt? A little from each? Potential problems from either?
Any other ideas? I appreciate any help or insight anyone can provide...

Thank You!

I had a similar issue with the same lower. My bolt was high-centering on the ejector though, instead of the feed ramp. I filed just enough material off the ejector to get the takedown pin through the upper, and now everything is running great.

Hope this helps.

 

[johnsland8]

Ok, what's the make of your 9mm upper. There are kinda "two" standards for 9mm lowers, colt pattern and oly pattern, the big difference between the two is that the colt will feed from a double stack mag, and the oly pattern feeds from single-feed sten mags.

The upper is from Daytona Tactical and is the Colt type

 

[johnsland8]

I've added a picture that hopefully will help show what's happening. I think I might try removing the feed ramp and see if there is anyway to remove material from the bottom so if I need to I can always shim it if I have any issues. It looks to be pinned into the lower so not sure this is an option...

 

[johnsland8]

I had a similar issue with the same lower. My bolt was high-centering on the ejector though, instead of the feed ramp. I filed just enough material off the ejector to get the takedown pin through the upper, and now everything is running great.

Hope this helps.

Ya, I guess that helps a little knowing it's probably just a tolerance issue. I thought it was hitting the ejector until I put a little grease on top of all the high points and pressed it together. It is clearly hitting the top of the feed ramp. I'm probably going to have to file this down until it will close, I'm just afraid of causing feeding issues...

 

[AMProducts]

Yea, looks like you're going to need to spend some quality time with the file on that. Before you do, you may want to contact the MFG's and ask wtf. Typically the lower block is pinned in place. this one looks to be entirely custom in that regard, so I'm sure it's pinned in, it's just a question of how this was done. I know I had more than a few problems with my OLY that required some hand work. It really bothers me that manufacturers don't do a better job of working through these issues.

 

[IronMonster]

PSA states that thier dedicated lowers are designed to be used with there hybrid bolts. I suspect if you used thier bolt it would have dropped in place. In any case seems a pretty minor fitting issue that is more of a pain than a real problem

 

[IronMonster]

Ok, what's the make of your 9mm upper. There are kinda "two" standards for 9mm lowers, colt pattern and oly pattern, the big difference between the two is that the colt will feed from a double stack mag, and the oly pattern feeds from single-feed sten mags.

Don't forget the Glock lowers now, colt bolts won't work without modification in those either. I have built 5 9mm AR's and have found that sticking with a single maker for the lower and bolt is a wise move. I have had to work over a bolt which was a bit tedious

 

[johnsland8]

PSA states that thier dedicated lowers are designed to be used with there hybrid bolts. I suspect if you used thier bolt it would have dropped in place. In any case seems a pretty minor fitting issue that is more of a pain than a real problem

Ya, That^^^^^ is pretty much what it boils down to.
And actually on there website it says their lowers "work best" with their hybrid "uppers" it doesn't actually mention the bolt. But if you go to their uppers it says they come w/ the G-9 hybrid bolt... so I guess you could surmise it works best with their hybrid bolt but it doesn't actually say that. Plus, they never have anything in stock. I watched for 2 months before they finally got the lowers back in stock, then they conveniently put them on sale w/ free shipping so I grabbed one.

I called them and emailed them to ask about the bolt compatibility and the bolt catch. The rep that answered the phone after about 30 minutes couldn't answer a single question about the lower and didn't seem to know how to find out. I finally got an email response from them 7 days later and that rep told me the colt lower uses a standard bolt catch, that only the glock lower used a special one. But he is wrong, they use a "long-finger" style bolt catch on the colt lower. Obviously, you can't rely on their customer service for any help.

At any rate, a little filing here, a little filing there, and it works like a champ. It's hard to expect to mix and match manufacturers on special parts and not expect to have to do some fitting. I just didn't want to do something stupid I couldn't fix so I was hoping someone could help me ease my thoughts. In the end, patience is the key, and it works.

Thanks for all the replies.