This is Double Bell’s take on an integrated hop up system :
The theory being that with air venting through the top slots before the gel exits the barrel the pressure differential imparts back spin and therefore hop up. I can vouch for it working on their G17 pistol quite well.
Before I go breaking out the needle files and die polisher and go destroying a perfectly good inner barrel, has anyone in the group tried this with a full length rifle barrel? 
they work well in gas pistols. Got the in M9, 1911, G22 and hicappa 4.3. Increased range and accuracy Haven’t tried it in AEG barrel
This is advertised as something “modern”, but has its basic theoretical properties dating back to WW1 firearms designs.
I’m so sad that I had soooooo much research and technical information that I had posted about on the old GBF regarding this type of stuff that has now been lost forever 
I’m not going to comment any further than suggest that you check out what barrel compensator modifications that GLOCK designed for their fully automatic G18C pistols.
I still have a shitonne of theories which I had tested and proven years ago in relation to these types of modifications as part of massive amount of work that I put into barrels, flash hiders, muzzle breaks, suppressors and “air pressure exiting barrel control and transition into the atmosphere.”
Rings a bell (pardon the pun) that type has been tested before on longer barrel AEG and was not effective. Few years ago, can’t remember where or who besides being overseas. I can’t find anything about it currently.
Give it a go and post your findings. Maybe it will work on a GBBR due to different air impulse. One way to know, it’s out with the die grinder and needle files for you 
It was extensively trialled in Airsoft quite a few years ago and had a few different companies offering different barrel “attachments” , similar to the “sweetheart” style design as alternative barrel fitted hop-ups instead of the traditional Airsoft t-piece bucking designs.
I imagined that this design never took off all those years ago because it obviously never actually worked out on air powered Airsoft/Gelblaster dynamics.
It definitely worked for the GLOCK Company on their factory testing systems and final product design specifications for their G18C Full Auto Pistol…… but that’s obviously because that is a real firearm, not a kids air powered toy 
As per my previous comment, I already looked into this way before anyone else ever thought about using this design…… and hence why I just wrote it off as good in real firearms design, but completely useless in operation for Gelblaster use.
I am still so pissed off about how many thousands of hours, research, pictures, videos posts and threads that I lost from the GBF, simply because I posted all of this information directly onto the site, without any backup saved on my phones and I don’t own any computers or use I-Cloud or whatever…… so all of this history is completely lost 
I think that was it if I recall correctly. Nothing to do with airsoft but sweetheart after their initial success did trial some rifle barrels with slots cut in them similar to the bell pistols. For AEG gel rifles. Then they seemed to disappear. Pretty sure that Galapous J fellow reported on them on his channel, but that all got deleted. He was a friend of the sweetheart person and trialed new designs testing out.
Don’t qoute me on that, I could be well wrong.
Yeah the Airsoft whoever company at the time was replicating the physics of real firearms compensation slot designs, which predated the Sweetheart carryover design for Gelblasters.
So for the sake of clarity……. a couple of Airsoft companies tried to market it first and it failed.
Then the manufacturers of Gelblster accessories such as Sweetheart took up the idea as a new marketing product…… but failed very quickly as the Gelblaster market at the time was basically only Asia and just becoming popular in Australia.
By this stage, the Airsoft industry had already discredited the design and the burgeoning Gelblaster market was skeptical about the product as having already been shot down in the Airsoft industry.
Sweetheart still pushed forward with even more “groundbreaking” designs, but again, weren’t very popular and hence were very short lived.
In theory this sounded pretty good for Airsoft, but as we all know and understand, Airsoft technology has undeniably proven that bucking hops in the t-piece are the best design proven so far.
Gel Blasters are much different, and do require a buck/hop/ramp etc at the end of the barrel, not at the start.
From all of the old bullshit that I watched way back then in regards to slotted barrels, there was a heap of Airsoft tuners who trialled and dismissed the whole concept.
I did trial the idea myself with several different clear plastic stock and different spare Aluminium barrels, with some many different head scratching theoretical designs applied to them all……… but everything amounted to feckall at the end of the day, especially when compared against the effectiveness of simply just adding a RIZER or JK printed hop to the barrel instead
Yeah, different sized slots at different lengths, angles, distances, dimensions yada yada yada, and then the pain in the arse of trying to clean/smooth/de-burr the inner surface etc all made for a shitonne of hours/work/testing for basically nothing compared to fitting a normal hopup at the end of the day 
Sweethearts were very popular, minimalistic trying to get a rl look. They worked well when matched with your gel of choice, I still run a couple for that reason. Nothing else fits and I don’t want to ruin the look. They are firearms anyway so may as well make it look like one. 
On that score you’re definitely not Robinson Crusoe, Doc…
The wealth of technical info and breakthrough designs on that forum was phemomenal. All lost to the ether now.
Sweetheart hopups always seemed to me to be pretty variable in their results unless you were fully into controlled grows and pretty stringent gel grading. Like you said, only worked with particular sized gels.
Control and grading is something I need to be a bit more proactive about if I want consistency, for sure. My gels are all over the place like a trench soldier’s shit.
Gel consistency is rubbish at the moment. Brewed some elites for 4 hours - half were under 7.1 - when the previous packet, brewed the same way on the same liquid, had about 20% over 7.3.
I remember they were shit back in my legal days…… especially after getting a set of Sieves from Zhenduo and actually properly grading the various different brands of gels 
Surprised that the modern manufacturing industry still hasn’t been able to regulate production quality, but I imagine that it’s still a difficult process considering the physical aspects of the gels/growth process themselves
Having the same inconsistency issues with Elites, AKs, X-Force and Gladiators. Not just an Elite problem. AKs have been the best for a while but this latest batch is just an inconsistent as the rest
The very last gels that I got to use for AKA’s, X-Force Black Labels and the very latest release AUSGEL Ultra Elites.
Unfortunately the Elites were probably the worst for size consistency out of the whole bunch…… even though they were amped up as the latest and greatest thing on the market.
Most of my best performance gels were the old green/blue OOTB old school original 7-8mm gels!
If gel really takes off in the US and other AS allowed countries, you can bet they will get into better heavier gel manufacturing!
Then wait for Aussie retailers to rebrand them as their own!
It’s that rebranding by retailers that’s muddying up the water.
I got a packet of iHobby frosted white gel balls with my G17 SAI, grew some last night. Seem to be close to Ultra Elites, haven’t had a chance to evaluate size variation yet.
I cut four slots into the top of the inner barrel of my 300FPS M4 today, just to see if it made a difference… it didn’t. Neither did five slots.
Makes this post fairly moot, I guess. 
Yeah…… they been there/done that years ago with Airsoft, and the same with my own experiments……. definitely was a waste of time and effort
Fortuntely the IB was about two inches too long anyway…
