Jump to content

ProWin M4 Chamber for Marui M4 (AEG) Review


Recommended Posts

Prowin HOPUP

 

Intro

This is my first review of a product so forgive me if I miss anything. I am a professional engineer so you will have to excuse my poor punctuation and prose.

I have been airsofting for about 5-6 years now and have always built my own guns – predominantly m4, AR-15s etc

 

I was, at one point, considering manufacturing my own improved CNC hopups as they have long been the Bain of my existence (over exaggerated for effect :D ).

 

Recently I purchased a couple of Madbull 3 in 1 ultimate hopups, and although I was impressed with the way they functioned and their consistency, I was put off slightly by the price, the shoddy casting and the rubbish pot metal from which they were made. One of th ones I purchased was so poorly cast that had to take a Dremell to it, to remove the excess material that was preventing BBs from feeding, not what you would expect from a premium priced product.

 

Anyway I digress.

 

A couple of weeks ago I stumbled upon these:

 

Prowin m4 chamber for Marui M4 (AEG) - $21!

 

Half the price of the Madbull equivalent, Full CNC from BILLET, not cast then CNC finished (like some of the cheaper items that have been popping up recently)

I thought that this was too good to be true, so I purchased a couple of them to test them out and this is what I found….

 

Installation

The hop unit comes in a small bag without instructions. To be honest I did not care, there are so few parts, a chimp could figure out how to put it together,

 

3 min’s later… built, where’s my banana…

 

IMG_0416.jpg

 

Notes

O-Ring

 

The o-ring on the rear of the unit has a tendency to fall into the first groove (meant for the retaining C-clip) and can be a pain to try and remove if this happens. My solution; use a dental pick during installation. By keeping the o-ring looped over the pick (you could use a paperclip) you can prevent it from falling into the first groove and can pull it all the way onto the correct one.

 

IMG_0417.jpg

 

Barrel spring

 

The front of the unit has a long grub screw, where there would normally be a small nub for inserting the barrel spring. This spring fits into an indent in the outer barell and provides the necessary force to push the hop unit back against the mechbox and seal the system. This is an important spring and can sometimes become lost if the rifle is taken apart and cause performance issues if omitted.

 

With the Prowin hop unit, it is possible to set this grub screw long enough (with a little thread lock) as to provide a permanent seal against the mechbox without this spring. But I would not recommend this as the shock transfer through the mechbox would no-doubt do damage to the unit after a few games.

 

IMG_0423.jpg

 

As there are no instructions I am unsure what the correct course of action is supposed to be.

It is possible to fit the regular small spring by screwing it down the shaft of the grub screw. However I found that the grub screw in this instance was too long, and would cause the spring to bind around the shaft and lock the hop unit into the outer barrel, thus negating the point of having the spring and causing poor sealing against the mechbox.

 

My solution! – The barrel spring – This is a method I saw used in my G&P SR25K URX

Instead of using the grub screw and tiny spring, we will remove them both and use a strong larger diameter spring around the inner barrel.

 

This method provides a much stronger seal between the mechbox and the hop unit, not only because it is a stronger spring but because the angle of contact of the spring is in line with the nozzle of the mechbox, thus allowing the two to mate perfectly in-line.

 

In addition to the improved sealing, this larger spring also has the added benefit of mating the upper and lower receiver together with greater force, removing (some) of the wobble that can be common in certain brands.

 

IMG_0427.jpg

 

Hop rubber/nub

Hop rubbers can be a pain. I have a box full of hundreds of them all unmarked. My advice is to find a brand that works, and stick to them.

 

I found the Madbull hop unit to be very fiddly in this respect. With the Madbull unit I was unable to fit a Madbull hop rubber with a Madbull inner barrel, as the coating on the inner barrel was too thick.

With the Prowin unit however this was not an issue. I fitted a G&P hop rubber into the Prowin unit with a G&P inner barrel and they fit together perfectly (just tight enough to slide in, without forcing the inner barrel so much that it wrecked the hop rubber).

 

Initially I used a G&P hop rubber nub, but I did find that this was a little bit too large (diameter wise) and prevented me from being able to turn the hop fully ‘off’. I believe this to be due to the design of the hop unit. It has a relatively long throw with very fine adjustment however, at the ‘hop off’ setting; it is already partially engaged (with this hop nub).

 

Fortunately I had a smaller OD hop nub in my box of tricks, if this were not the case I would probably just have made one out of some silicon wire insulation. I imagine 18AWG would have been about the correct size.

 

With the new hop nub installed the unit works flawlessly with a full range of usable hop throw from ‘full on’ to ‘full off’

 

IMG_0432.jpg

 

Conclusion

 

Well, overall very pleased! At half the price of the Madbull hopup, these are an absolute steal! I am yet to run these for any length of time; however my initial impression is that they are very well built, when combined with a good hop rubber/nub they are very consistent, and offer improved performance over stock setups. I think I will be swapping my Madbull units with a few more of these before they sell out!

 

IMG_0439.jpg

Link to post
Share on other sites

i've been looking at this item. Great looking thing. Even greater review. Thanks!

 

1. Question - does it come with plastic pieces? cause G36 Prowin was without them?

 

2. How is compatibility with other brands? CA, ICS, Diboys?

 

3. Would you recommend it for DMR set up.

Link to post
Share on other sites

Does it come with a small barrel spring? Didn't see one in your opening photo.

 

If there's no spring included, perhaps then you are meant to screw out the grub screw until there's no play between outer barrel, hop-up, and front of gearbox. Though as you say, that does seem rife with problems.

Link to post
Share on other sites

i've been looking at this item. Great looking thing. Even greater review. Thanks!

 

1. Question - does it come with plastic pieces? cause G36 Prowin was without them?

 

2. How is compatibility with other brands? CA, ICS, Diboys?

 

3. Would you recommend it for DMR set up.

 

All included parts are in the first pic

you need to add:

the small barrell spring (if you decide to install one)

Hop rubber

Hop rubber nub

Brass barell shim ( i dont know what you call this item, the small brass ring that slides over your barell)

 

I have only tried them in G&P 'complete guns' and my own builds, which tend to be G&P/SYSTEMA etc

 

I have one Dboys mechbox in a King arms gun that i was going to install one to, but i am awaiting some more barell springs (will update later)

 

it seems to work perfectly with everything i have thrown at it, it is built for a TM platform so it should be fine.

 

As for a DMR setup... i dont think the role of the rifle is going to make much difference, it either works or it doesnt. As long as your DMR uses a standard m4 hop unit like my G&P SR25k URX does, it will be fine

Perhaps if you were running greater than my 350fps, or using a Pre-cock mosfet then the results may change, i cant comment, what with UK fps limits being what they are.

 

My main reason for changing to this syle of Hopup is that the adjustement rings are much more secure (being held in place with O-rings). My standard hop units kept on coming loose, particularly with high ROF setups. Each shot would have a different amount of hop - drove me crazy!

Link to post
Share on other sites
  • 2 months later...

I installed this on my King Arms M4 and it works perfectly, I also used a promothesus purple hop up rubber and and promothesus 6.03 inner barrel, as mention in this review the spring over the barrel is an ideal solution. My intial results our very consistent fps and great accuracy with this combination I will be installing two more on my VFC guns and giving them a through evalution I will post up in a couple of months and let you know after some use if there holding up.

Link to post
Share on other sites

I installed this on my King Arms M4 and it works perfectly, I also used a promothesus purple hop up rubber and and promothesus 6.03 inner barrel, as mention in this review the spring over the barrel is an ideal solution. My intial results our very consistent fps and great accuracy with this combination I will be installing two more on my VFC guns and giving them a through evalution I will post up in a couple of months and let you know after some use if there holding up.

 

I just ordered a Pro Win chamber and Prometheus 6.03 EG barrel for my SR-635. Will post my findings here.

 

At first, I will be using some stock buckings (VFC and green G&G) to fiddle around with an R-Hop build, and finally move onto a Prometheus Soft (Purple) once I get comfortable.

 

-Ex

Edited by Extraordinaire
Link to post
Share on other sites

I just ordered a Pro Win chamber and Prometheus 6.03 EG barrel for my SR-635. Will post my findings here.

 

At first, I will be using some stock buckings (VFC and green G&G) to fiddle around with an R-Hop build, and finally move onto a Prometheus Soft (Purple) once I get comfortable.

 

-Ex

 

From what my friend working at Redwolf tells me; the nub cutting is too small to fit a firefly flat nub. This means you'll have issues making a nice R-Hop if you can't use a flat nub in the chamber.

 

I don't have pics of the pro-win chamber itself but was thinking of getting one. When you get yours Extraordinaire can you please take a pic of the hole where the nub fits?

 

I suppose putting the chamber in a vice grip and using a drill to make the hole longer would mean you'll be able to fit a flat nub like the firefly or a custom one for the R-Hop, but its just an idea floating in my head at the moment as I don't have any experience with the Pro-Win chamber yet. Pics will help me solidify my theory on modding the chamber for a flat nub, thanks :P

Edited by intinerious
Link to post
Share on other sites

Your friend is right, but it's not too far from fitting. Here's mine with an x-nub in place, and a Firefly buffer rubber dropped in beside it:

 

SDC10812.JPG

SDC10814.JPG

 

Luckily the sides of the nub area don't need to be enlarged, so they'll do the job of keeping the Firefly aligned. Just going to open up that rounded window enough for the nub to clear.

 

I'll probably replace both of my Modify chambers with these as long as the Firefly mod goes well; it's much easier to make precise adjustments with the ProWin unit.

Link to post
Share on other sites

Thanks for the pics kojak!

 

Well, the hole for the nub isn't as small as I imagined before; in fact it's just the rounded edges that need to be widened out as you said. Perhaps there is a drill bit that's just the right size so that when we fit it into the chamber it'll just elongate the ends of the hole without drilling a bigger diameter?

 

Given that I think the current hole for the nub is right in the center of the barrel bucking opening; I suppose both ends of the hole will need to be widened with a drill bit or a needle file. I'm not sure whether a small needle file can fit into the hole for the nub without grinding down the sides of the chamber tough....all the files I have at the moment are huge and generally used for big stuff like shaving down metal teeth on my pistons. Sooo...anyone have any ideas whether a needle file will fit just right and be able to widen the hole without the need to resort to a drill bit + vice grip? :P

Link to post
Share on other sites

I had some issues with these in my VFC's trying to get them to seal up correctly. I am shooting .25 and getting around 310fps when it is correct when it is not I am getting 75 to 80 Fps I tried three different brands of hop up rubbers and various springs trying to get it to seal I even put a small 1mm x 6mm o ring on the back where it enters the gearbox and resolved one of the seal problems on one of the guns. but the other I have no idea why it is giving me the low fps.

Link to post
Share on other sites

Mine sealed just fine after some trial and error with the set screw (the typical spring pressing the chamber against the gearbox is a lot easier to deal with). I had misfeeding with a couple of buckings but settled on a lavender Falcon 90° that the system seems to like.

 

Dremeling out the window was pretty easy with the right bit, and performance has been excellent so far.

Link to post
Share on other sites
  • 2 weeks later...

Seeing as though I don't have the spring as pictured above, I've managed to get quite a nice tight fit for my Pro Win chamber.

 

P1020133.jpg

 

I used various O-rings I had laying around in combination with the plastic rings that are supplied with small tubes of super glue. These rings are designed to keep the tube from being punctured and are removed when you are ready to use the glue. The size is PERFECT to slide over the inner barrel. It's really quite interesting that these are the right size to slide over inner barrels and not impede with inserting the hop unit into an AEG.

 

Using one O-ring and a spacer ring from the super glue, I have a super tight fit for my Pro Win chamber in my VFC SR-635.

 

P1020136.jpg

 

-Ex

Edited by Extraordinaire
Link to post
Share on other sites
  • 1 month later...

OK 2 points:

 

1. The hopup rides a little too far forward and needs a strong spring to push it back from the receiver recess in order for you to not get an air leak. I recommend getting a stiff spring that wraps around the barrel itself.

 

2. A firefly flat nub DOES fit, and it fits well. Just have to do a small mod where you cut off the 4 sharp corners of the nub. IMO this is quite preferable to actually taking a dremel to the chamber window itself. Once you round off those corners, the nub will go in with a near perfect fit.

 

I did it for my Avalon BCM and the results were phenomenal.

 

Overall this is a great unit, much superior over the madbul version which was both expensive and poorly cast.

Link to post
Share on other sites

I avoid butchering the Firefly buffer rubber since the large surface area is what makes it great in the first place. It takes me about thirty seconds to enlarge a chamber window (I've done four of them now).

 

I need to find some more of those barrel springs. Any ideas on a source?

Link to post
Share on other sites

Installed mine into my G&P using three orings rather than the spring.

 

Works like a champ.

 

I used a guarder clear bucking and nub, and (as mentioned previously) the arm does press the nub/bucking fairly deep into the barrel. Right now I can't have the hop-up set entirely off, but it doesn't seem to affect performance.

Edited by Gigueand
Link to post
Share on other sites
  • 6 months later...

Decided to buy one of these as the hop unit the came with my g&p was not working right, fitted perfectly onto the standard g&p barrel with a prometheus hop rubber and element h-hop ( i think thats what it's called) and worked nicely in the gun. I have just recently purchased a madbull tightbore to help with the grouping, all fitted perfectly together like the previous set up.

 

Would highly recommend this hop unit to anyway as it allows for more precise alterations of the amount of hop. I also find it alot easier to use with and without gloves compared to a standard style m4 hop unit.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use and the use of session cookies.