J10 ACR - ideal barrel length and hopup?

Hi all… currently have ACR J10 and M4 gen 9. I am having a fair few issues getting the ACR to shoot straight (compared to the M4). Anyone have suggestions of ideal barrel length and a hopup that actually works on the ACR. I have tried a few and put a hopup from M4 that is shooting straight on to the ACR… and it is all over the place…any ideas help will be greatly appreciated!

Welcome mate. @Matth1000 might be able to help you out or @LowGuido

Id first check that your barrel is clean and undamaged.

I opted for the 34cm Bruisemaster, I wish i had of gone 40cm.

Thanks for the replies. I should have mentioned I have tried a few barrels. I have 1.3mm spring, green o ring and running 11.1v battery. It is shooting around 280 fps but not accurate!

Yer I have about the same. When shooting beside the Gen 9 with a 40cm Bruisemaster, the ACR falls short on accuracy.

The hop ups seems to make it so much worse!

Yer i removed mine also. Getting quite the collection in the toolbox I might add, I seem to buy a new type every time I got into a shop thinking the different brand might make a difference. I should add that I installed the ACR outer barrel stabiliser when I removed the hop up.

Are you putting the hop on the inner barrel or the outer?

I have tried both…which do you suggest is the best? It is super frustrating when you have the M4 shooting well and can’t get the ACR to do the same.

Check that your barrel is not bent, roll it around on a flat surface.
Try with out the hop up and check accuracy.
Also try going back to a 7.4v,
The gels might be hitting each other in the air with increased rate of fire from 11 volt.
Going back to 7.4v will give them a little more distance between them and allow them to exit the barrel one at a time.

Yeah I have added stabiliser on the ACR and o rings between inner and outer barrels on both M4 and ACR. Don’t get me wrong it works…but it is no where near as accurate as the M4. Just wish I could nut this one out.

Hi…Ive used a 1.2, a 1.25 and a 1.3 spring…the ONLY one that works and still keep accurate shots is the 1.2 as soon as I go above that they can be up to a mtr spray over 10~15 mtrs…hop up or not makes no difference. With a 1.2 DK hop up…I can hit a beer can at the same distance consistently.


Do you know what is the most accurate fps?
I have found at 280 and above mine go all over.
@anon78062304 also said about 260 is the sweet spot

No idea mate. I have just found my latest batch of green gels are all messed up…see pic!
Currently going back to the drawing board and starting from scratch. Although I did run some standard blues last night which seemed to shoot pretty well! 1557652746970261414367|281x500

Did anyone else have a problem with the magazine not clicking in after replacing the barrel?

Just an update…

DK J10 hopup…clear ghosts…now shooting really straight and accurate. As they are a smaller gel I am going to run a tightbore and see how that goes.


Was the hopup on the inner or outer barrel? Alloy? Stock?

Having same issues myself :frowning:

Gday again…DK J10 hopup on barrel. Alloy barrel 35cm. I have just chnages out the 1.3mm spring and installed 1.2mm spring… still running 11.1v. I have finally got it to shoot pretty straight now. I have been using heavy milkies and clears. They are measuring around 7.2mm which the ACR seems to love.


Where do you get your clears from? I got an acr for my first blaster a fortnight ago, but the accuracy seems off so far. So I’ll try what you’ve done and see how it behaves