A-5 low velocity

[oats944]

Good afternoon gents, my 11 year old son just started playing and I picked up a used A-5 with an RT kit in good condition on the cheap. Went to the field yesterday and couldn’t get the fps over 220-240. Started all the way in and gradually went all the way out on the velocity screw and I’d occasionally hit 250.

I read everything I could online and folks with similar problems changed the hammer spring with a minor velocity increase (5 fps). From my research this is an older A-5 without the thumb safety selector, which has the 2 outside channels on the valve in the power tube instead of 4. Word on the street is I need to get the newer 4 channel valve to get the velocity up.

All my hpa tanks have regular/high pressure output, and they all yielded the same results.

Before ordering anything, does anyone have experience with this issue and changing to the 4 channel valve? Thanks!

[Toestr]

Did you replace the hammer spring with a heavier one from a kit or just a replacement stock spring? I can't see a heavier spring only bringing you up that much. Your issue probably stems from small paint.

[markdem]

Ive had issues with knock-off ball detents being oversized and creating drag on the bolt, lowering velocity

[oats944]

Thanks guys! I should clarify that I haven’t changed the hammer spring from what was in there when I got it. The condition of the gun made me think it wasn’t used that much so I don’t think there are a lot of miles on the spring. My first guess was to change the spring, but I read on some other forums that people that have had the same issue changed the hammer spring to the hardest one in their kit, and didn’t have much of a change. That’s when I stumbled onto the new 4 channel valve as a potential fix, but there weren’t any follow up posts that said it actually worked/got the velocity up.

The paint at my local field is small as I was getting some rollouts out of a .675 sizer on my cocker. But the cocker, mags, and a G4 we used all reached proper velocity.

I put in a new Tippmann detent when I got it so hopefully that’s not the issue.

Thanks again for any assistance!

[EvilCreature]

The hammer spring could have been stored in the cocked position, which damages the spring over time, lowering velocity. If it isn't clean inside the gun drag can be any issue. Also, make sure your tank really is running 700 psi, maybe a little more. Lots of tanks run close to 600 which isn't so great for Tippmanns.

[JonM]

The issue I had with the A5 was related to the small bore paint used today, the wider bore barrels commonly used with the A5, and the stock hammer spring. I’d start by trying a heavy spring and see where velocity is. This is the simplest and cheapest option before you start getting into barrel kits.

[AnarchicArctic]

What bore was the barrel? Sub .675 paint can definitely cause velocity issues with large bore barrels

[oats944]

Thanks guys, I’ll start with the spring, as mentioned above it could have been stored in the cocked position.

Marker came with a spyder barrel to A5 adapter and I was using a .685 HK one piece spyder barrel I had hanging around. I was shooting a classic mag with a 14” twist lock with an even larger bore with no velocity problems so I was thinking it was more of a problem with the A5 than the barrel/ball combo.

[Magmoormaster]

Older Tippmanns are fairly well-known for not always getting up to velocity with compressed air. The valve flutes you mentioned being a primary factor. I worked on an A5 with this problem and I was not able to get it up to veloctiy with springs.

If you can, try testing it with CO2 to confirm that it's not something else entirely.

It should also be said that no, keeping a gun cocked will not wear out the springs.

[oats944]

Thank you! I wound up ordering a spring kit and a valve with the 4 channels/flutes. Figured I’d try the new spring with the old valve, the old spring with the new valve, and then the new valve and a new spring to see where I end up. Unfortunately I don’t have a co2 tank or a place near me that fills co2. I’ll report back what happens to hopefully help someone else that may be in the same boat.