This “Deep Fire NEW HOP-UP 14.5 inch Outer Barrel Front Kit for AEG M4 series” comes from Scopeandlaser.com. I was so excited when I received it in the mail that I had to open up the package in my car and start taking photos of it with my phone. I couldn’t wait but get it installed at work, so a plethora of phone pictures that are most likely out of focus are as follows (after the break):
I found that the PTW hop up design does in fact perform better than what you can probably get out of a M4 hop up chamber – there is less give and flex and wobble in the parts that come together to produce hop up in the PTW than in an AEG. So when I noticed that Deep Fire had released this barrel kit a few months back, I decided that I would definitely give it a try – a PTW hop up in a tuned M4 AEG has got to perform well, right? At the very least, I’ll have a hop up that won’t be backing off on me as I play, but that is compatible with my many, many PTS PMAGs. Here’s hoping that this one actually works, contrary to some of the drum hop chambers out there, like the Madbull and Pro-Win I’ve previously tried in my King Arms.
I do order from Scopeandlaser from time to time – they often have latest parts still in stock that some of the larger Hong Kong retailers don’t have. As that store isn’t so well known, they tend to be a little bit slower to pack up and ship (I figure it is a one man operation done by Patrick there) – but they ship via HK Post in packages that are suitably sized and padded (or not), based on whatever product they ship out, meaning that shipping doesn’t cost an arm and a leg for something small like a hop up bucking.
This “new” design was actually used in Deep Fire’s older Gold series (or one of those series) AEG M4s that are no longer in production. It strongly resembles a PTW hop up design – however the chamber, outer barrel, inner barrel sleeve, and inner barrel are in fact different in dimensions and are (as far as I can tell without trying them) incompatible with existing PTW or AEG parts. Initial impressions were very good at this point in time – the machining and finishing on the barrel seemed to be very well done. Hop up chamber is obviously cast pot metal though, more on that later.
Quick note – the one I received only has a single hop up cage cushion (small rubber bit that acts as a spring to keep hop up cage from moving wherever it pleases when hop up is set at 0%; that being said, the box to my hop/barrel kit did appear to have been opened previously.
Disassembly/reassembly is very similar to a PTW hop up, except that there are a few additional O-rings here and there – presumably to ensure a tight fit and good air seal. Note that the hop up roller is not the full length of the cage – this does cause inconsistency in hop up effect applied in Systema PTWs, and I will be fixing this when I’ve got the hop up chamber properly fitted to my King Arms.
The hop up chamber has no spring at the front and thus requires a precise fit with the upper receiver in order to transfer the shock of the gearbox cycling towards the upper receiver (hopefully this works and helps prevent my current gearbox shell from cracking). It currently requires fitting to fit in the King Arms (Colt) M4A1 upper receiver, though seems to be a drop-in for the Ares. I have not yet shot through the Deep Fire hop/barrel kit, so I can’t yet confirm if it works in either, what FPS I’m getting compared to the previous hop up, how far it shoots, etc.
I was hoping that it would be a drop-in fit in the King Arms, but now that I’ve compared the KA upper receiver to the Ares, I can see why it wouldn’t be. The King Arms upper receiver has a reinforcing block (in the area where the gas tube inserts into the upper receiver) that is not present in the Ares upper. This means that with the Deep Fire PTW-Style Hop/Barrel kit installed into the upper receiver, the upper and lower receivers don’t have enough clearance to fully close as the hop up chamber is slightly too long for proper fitting in this instance.
My solution to this is to slowly file away at the material on the front of the hop up chamber until it fits snugly but properly against the upper receiver. Any wobble here (without the addition of a spring or shim) with definitely create an air leak. Good thing though, the hop up chamber is pot metal as mentioned earlier. I’ve slowly started to do this tedious process (file-polish-test fit-file-polish-test-file-polish-test… etc) at home.
Oh well, at least I finally hacked off the King Arms barrel nut – on some of these KA Colt M4A1/M4 CQB the barrel nut is impossibly tight on the upper, meaning that you can’t just torque it off without some sort of crazy machine that I definitely don’t have access to. Solution? Cut off the delta ring assembly with an angle grinder.
I guess this is where my photo review of the Deep Fire PTW-Style Barrel Kit ends – I’ll have to post a update when I’ve got it installed and working. I’ll link that update through this write-up when its up.
At the $130-ish price tag (including shipping), it better be amazing and totally worth it. I was actually considering selling this King Arms M4A1 at one point in time, however I decided to keep it due to the money invested in it and for sentimental reasons. So… I decided that I might as well throw more money into my KA M4A1. And so here we are.