top notch ump

[sonnydaze]

i got a top notch grease gun mag ump for christmas it has the early aluminum lower . im going to switch out lower should i go with an fbi lower or the polymor top notch grease gun lower
pluses for tn lower
1 cheaper
2 us parts count
3 mags easier to get and cheaper
4 mag release is better

fbi lower pluses
1 hk
2 uses hk mags
3 has bolt hold open
4 be worth more if i decide to sell someday ( 4 is not that great of chance since ive regretted selling every imi gun ive sold )

if ive missed any thing give me your advise

 

[Nwcid]

Unless I am wrong the HK UMP upper and lower mount different then the USC conversion so it will not fit. I know there were a couple different conversions but I have the GG mag conversion and I KNOW that upper/lower will not interchange with the UMP stuff. I guess what I am really saying is make sure it will work as the stock USC upper will not work with UMP lower.

 

[sonnydaze]

ump lowers take a little filing on the hooks to fit but its about a 2 minute job . thanks for your reply , do you have the plastic lower or alumium one ?

 

[Nwcid]

The first lower I had was the one that used the "stock" stock. I traded it up when he was doing it for the lower to use with the folder. Both were/are plastic.

Here is mine:

Here is a UMP:

It is the pin hole in the rear that makes it not work. Well at lest with this set up. Again I KNOW with mine it will NOT work, but yours may have been converted differently.

.

 

[sonnydaze]

thanks for the pics it looks alot more detailed than i thought . whos rails are you running ? mine is the early aluminum lower i dont know how old it is but i called to get a new folding stock and lower like yours but it will be 2 weeks before he can ship , but no biggy mine still shoots fine .

 

[sunnybean]

Another benefit for the HK UMP lower is the bolt hold open feature...something the M3/GG lowers are missing.

 

[sunnybean]

Ooops, I just reread your OP and see you had that covered on #3. Oh well.

I wish I had a TN lower to compare with. I do like the HK UMP lowers, but I'd like to have a TN because I have a number of GG mags that would be fun to play with on this platform. Since I'm set up with the UMP lowers, it'll have to be a hell of a deal for me to get one at this point...too many other projects. I think you'll be fine either way.

 

[sonnydaze]

bean i could loan you my aluminum lower to play with for a few months when my new ones come in

 

[sunnybean]

sonny,

Thanks for the offer, but I'll have to pass...too many other things in the way. I'd be interested in your thoughts b/n the two once you get all set up. A good range report would be sweet. Congrats!

 

[sonnydaze]

sonny,

Thanks for the offer, but I'll have to pass...too many other things in the way. I'd be interested in your thoughts b/n the two once you get all set up. A good range report would be sweet. Congrats!

bean can i get pics of how you fbi lower works with your stock block . original had a pin but i dont see how you could get a pin in yours

 

[Nwcid]

whos rails are you running ?

I got mine from TN. Ergo Grip makes a nice set too.

 

[sonnydaze]

I got mine from TN. Ergo Grip makes a nice set too.

wish id have known i just shelled out major coinage for the set hdps has :grenade

 

[sunnybean]

sonnydaze,

Here's a rough attempt at showing how the lower works. Basically, you put the lower on the upper. Then slide the HDPS stock block into the lower. There is a "T" slot in the lower reciever that the block slides into to hold the lower from dropping out the bottom. This is all held in place by a pin. Ed has changed his pin types. The old blocks used the original USC screws that went into the threaded holes in the block. The new blocks are not threaded but drilled all the way through instead. The new style pins go all the way through and are self capturing (one side screws into the larger pin that goes all the way through). I like the new setup better as it allows for a tool-less breakdown and also a hook for a sling.

When you get the UMP lower you'll have to do two simple mods to it to make it work. Actually, the hardest part of the whole conversion is swapping the lower FCG. But other than that, the UMP lower will have a back stop (for lack of a better word) that slides back and forth a bit. Slide it forward and you'll see a little nipple that holds it from coming off the back. Take a razor blade to the nipple and slide the stop off. Take the buffer out of the back stop with a needle nose pilers and reinstall it on the HDPS block. Throw the back stop out. Then you'll need some sand paper to knock the 90 degree edges on the back of the lower down just a little bit. The HDPS stock block has slightly rounded corners where it meets the lower. Probably lost you there but it will all make perfect sense once you have it in hand.