Beretta A400 Cycling Issues

Big breakthrough today.

I tested the new piston but it still would not feed or lock back on last round.

The folks that supplied the piston also supplied a second part that replaces the spring on the front of the gas system. This part feels like a "Bleed Off" type deal that forces some (excess?) gas forward where it is bled off inside the hand guard. The hand guard is covered in soot from this gas so I know the port was opening for sure.

I installed that at the range and it transformed things. Gun runs great, feeds perfectly and locks back on last round. I even tried the Challenger 2 3/4 dram ammo (which has been terrible for me in every gun I tried it in) and it ran like a champ. Zero issues.

The nut holding the spring was tight so no issues there. I can only assume that the spring tension was too low and it was allowing too much gas to bleed off resulting in slow bolt velocity and poor cycling.

I had another gun there too and the A400 shoots very soft and the trigger is light years better.

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kevin g said:
WELL NOW....that's one for the good guys !! Sniffer, that's awesome news man !!
Persistence and the NFQ attitude prevails again. Might be some Matlock or Columbo in you...lmfao
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Thank you. Have learned lots about what makes these tick.

Looking forward to actually shooting the gun instead of firing a couple of rounds then swearing a bit because it still isn't working before stripping it again.

To those that own gas Berettas - what is a good cleaning number? 1000 rounds?
 
brybenn said:
Where did you get the aftermarket piston? Last pic looks marred along the edges. Did you use channel locks on it?
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Parts came from SRM Arms.

The marks are from channel locks (must have overlapped a little when tightening the nut). To be clear those marks will not matter as this is the replacement spacer for the spring (not the piston)
 
GimpyGolden said:
So the piston spring is replaced by a solid sleeve?
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Not quite.

Want to be as clear as possible so best way to explain it would be to think of the gas system as having two halves (we can call them front half and back half).

The back half is the non optional half and the one that has the piston so therefore does the work. The gas comes back at an angle through two ports, hits the piston which forces the piston back to cycle the gun. The spring to bring the bolt forward again (and move the piston back to its starting position as well) is inside a plastic sleeve between the gas system and action. This spring (on the back half / piston side) is quite long and is still in place (gun could not operate without it)

The front half is basically a bleed off for excess gas pressure from higher power rounds as I see it. There are a series of gas ports on the front of the piston housing sealed by a flat washer held under spring tension. This is the spring that was removed and replaced with a solid sleeve.

From my experience it seems that it is setup that for 2 3/4" (low power rounds) and should stay closed so the system harvests enough gas to cycle correctly. When using higher power 3" or 3.5" rounds the spring would allow the washer to move back thus opening the ports and bleed off some excess gas.

On my gun the bolt would never lock back on last round and would not feed properly. Both are indicative of low bolt velocity (bolt did not go far enough back to lock and would not feed correctly as the bolt needs to get back far enough to push the raised arm that operates the lifter flat or the round wont be presented high enough to enter the chamber) I videoed (slo mo) the bolt speed when firing 2 3/4" and it only made it 3/4 ways back so that proved my theory.

I have zero plans to shoot anything other that 2 3/4" rounds in this gun but if I were to shoot higher powdered 3" or 3.5" I would reinstall the spring (think I would get a new one though). I might pick up a new spring and retest at some point but for now I am loving how it runs. Shoots very soft. There is a hydraulic buffer at the rear of the A400 which possibly helps too (bolt is cushioned for the last 1/2" - dont believe this is on the other models, I studied a schematic for the 1301 Pro Comp and it looks like it is solid) and I thought might be part of the issue as it is additional resistance to overcome (see early posts in this thread for a picture of the part in question) but that was not the case.
 
Coles sells a spring kit for the front of the gas piston assembly that has several springs of varying resistance...not sure if it is just for the 3" chamber shotguns or interchangeable with the 3-1/2" chamber variety like the original poster has. I haven't used the kit, but could have on my 3-1/2" Extreme Plus to make it function with 7/8 oz skeet loads. Sounds like the original poster's solution would have worked as well, but not sure I'd want to shoot fast 1-1/8 oz loads without the spring to bleed off some gas.
 
Glad to hear that it's running well now!

From your description, it seems like the factory bleed-off spring is way too soft and bled off an excessive amount of gas, leaving too little gas to cycle the action. No wonder why the new spring made it work like a champ.

I do wonder how much harder it would shoot a 3" or 3.5" shell versus the softer, factory spring though.
 
Blockcaver said:
Coles sells a spring kit for the front of the gas piston assembly that has several springs of varying resistance...not sure if it is just for the 3" chamber shotguns or interchangeable with the 3-1/2" chamber variety like the original poster has. I haven't used the kit, but could have on my 3-1/2" Extreme Plus to make it function with 7/8 oz skeet loads. Sounds like the original poster's solution would have worked as well, but not sure I'd want to shoot fast 1-1/8 oz loads without the spring to bleed off some gas.
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I have shot a bunch of fast 1-1/8 oz 2 3/4" loads - no issue. Gun shoots very soft. To be clear before removing the factory spring the gun would not run these loads due to low bolt speed / cycling issues.

I will have a look at the Coles spring kit - thanks for the heads up.
 
BP4W said:
Glad to hear that it's running well now!

From your description, it seems like the factory bleed-off spring is way too soft and bled off an excessive amount of gas, leaving too little gas to cycle the action. No wonder why the new spring made it work like a champ.

I do wonder how much harder it would shoot a 3" or 3.5" shell versus the softer, factory spring though.
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From what I have seen the spring bleed off system is geared towards these heavier loads. I honestly think the system is setup to not open at all for 2 3/4" but open for 3" & 3.5"

I would not want to shoot anything over 2 3/4" without a spring.
 
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