Who's the expert on M4 uppers?

[Bourne4red]

I'm in the process of changing the upper receiver on my TM M4 S-System (as it has no delta screw).

 

I want a free floating guard adaptable to this, so my question is: What's the best fit?

[Lozart]

The thing to be aware of is that it's not just the receiver that needs to be compatible but all the ancillary parts as well.

 

I bought a Dytac receiver to replace the plastic one on my TM M4A1. Firstly the TM charging handle extension (the bit that pulls back the bolt cover to allow access to the hop adjuster) doesn't fit the profile inside the Dytac receiver. Neither does the bolt cover plate. None of which comes with the Dytace receiver. The Dytac receiver doesn't have the little plastic guide rail inside that the cover plate runs in either. That can be donored from the TM but has to be cut off and then glued back in, in EXACTLY THE RIGHT PLACE. All the parts that come with the receiver should be used where possible. For example - the TM mag release worked and was better made than the Dytac one, but it was actually very slightly too long and didn't release reliably so had to be swapped out for the Dytac one. I had to buy a Dytac charging handle (from Hong Kong) to fit properly. Also thing like an Element delta ring won't fit, but a King Arms one will and so the list goes on.

 

If you're going to change your receiver get one that comes with as many of the parts as you can unless you enjoy fettling little bits of cast monkey metal until they fit/break. I would suggest a Guarder kit but then you have to ask whether the rest of the gun is worth spending £150+ on just for having a floating rail.

[Bourne4red]

Thanks for the response, I was thinking...

 

http://www.ebay.co.uk/itm/A-P-S-ASR-Upper-Receiver-Set-for-M4-M16-AEG-APS-Logo-BK-APS-AER008-URS-/321335706337?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item4ad119c2e1

[Lozart]

Thanks for the response, I was thinking...

 

http://www.ebay.co.uk/itm/A-P-S-ASR-Upper-Receiver-Set-for-M4-M16-AEG-APS-Logo-BK-APS-AER008-URS-/321335706337?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item4ad119c2e1

 

Difficult to tell from an ebay listing and I'm not particularly clued up on APS as a brand but I would bet good money on it not matching up properly with your lower receiver.

[M_P]

Uppers and lowers from different brands tend to be a bit of a gamble as to whether they fit, they're all slightly different for the most part. Best thing you can do really is look at the asian retailers for a cheap metal upper and lower and do an entire swap over, atleast then you'll know they work together and also you'll have swapped your tm plastic ones for metal ones.