391 Gas Valve Spring Modification


Bruce:

I own a Beretta 391 which I’m very happy with, but I also like to reload my shells. The 391 seems to toss my empty hulls a mile which isn’t too much of a problem on a skeet or 5 stand lay out which is very open. In a woodsy sporting clays situation however the hulls disappear into the brush and retrieving them isn’t that practical cause it takes too much time to hunt em up.

I presume the reason for this is that the 391 is designed to, and does in fact, cycle everything. I use the gun primarily for target shooting and use target loads, although I do use it for ducks as well and feed it 3 inch 1 3/8 oz steel shells for that. I don’t reload the steel so I don’t care about those hulls.

Is there a different spring set I can use for target loads that will keep the target hulls from flying into the next county? I’ve also heard of but never seen “hull deflectors” that are supposed to knock the hulls down as they are ejected. I’ve used a hull catcher which is fine for singles but not doubles. Any Technoidal insight would be appreciated.

Thanks,
John.

Dear John,

You have a number of choices of ways to change hull ejection on the 391.

One of the easiest was is just to order a T&S shell clip from Brownells, http://www.brownells.com. It costs around $10. It instantly snaps onto the side of the gun and retains the fired hull for easy extraction. It snaps off just as easily. The downside is that it only functions as a single shot. If you are going to shoot doubles, you can’t use it. All the trap shooters use them. In addition to the T&S, there are and were any number of other gizmos to catch hulls. All of them, except the Morton modification, made your gun into a single shot. Unsuitable for sporting, of course.

You might also consider a shell deflector stud. You’ll need to be handy with tools or get a gunsmith for this. An ejector stud is simply adding a small “bump” in the barrel extension on the ejection port side so that the shell is deflected down towards the ground. If look carefully at the barrel extension on a Remington 1100/11-87 Trap barrel (not on any of their other barrels, just trap) you will see what I am talking about. The ejecting hull hits the little bump on the way out and gets angled down towards the ground.

The third way is to order a set of Rich Cole’s 391 valve springs. Here’s how they work: When the 390/391 fires, a small porting of the gas goes through the gas ports in the barrel and into the gas chamber under the barrel. Obviously, gas pushes equally in all directions. Inside the gas chamber there are two ways for the gas to go.

1) pushing the piston rearward and thus operating the action, and

2) pushing forward against the gas valve.

In operation, the gas valve’s function is to open first to bleed off excess gas so as to regulate the amount of gas used to push the piston. This in turn regulates speed and vigor with which the action operates, which governs how far the empty is tossed.

This gas valve is regulated by a valve spring. By changing the strength of the gas spring, you can regulate whether that valve opens early or late and by how much. If the valve spring is strong, the valve won’t open at all and all the gas goes to operated the action. This is perfect for a very light load that needs all the gas it can get to work things. When a heavier load is used with a heavy spring, the action cycles very quickly and tosses the empty a mile. When a lighter gas valve spring is selected, the gas valve opens earlier and bleeds off more gas, thus causing the action to cycle slower and not heaving the empty as far.

So, by getting a set of Rich Cole’s gas valves (quite inexpensive) and tinkering a bit, you should be able to regulate the bolt speed of your 391 and thus it’s ejection distance as to a specific shell. If you always use the same shell in the gun, then use a gas valve spring that will pitch the empty about six feet or so. That assures adequate bolt speed for proper functioning, but avoids the excessive bolt speed that increases wear and tear on the gun.

Most people find that the 391 works just fine as it comes, but if you like to tinker for not too much money, swapping gas valve springs is fun to do. You can always stick the original back in. The valves for the 390 came color coded and perhaps the ones for the 391 do also. You can confuse the enemy by asking an opponent whether he’s maximized his 391’s performance with the special light blue spring or does he prefer the red. It’s always worth a bird or two.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)
http://www.ShotgunReport.com

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2 Responses to 391 Gas Valve Spring Modification

  1. Mike Yunkmann says:

    I had a real “smuckers” issue w my 391 Tgt – jam, jam, jam. Running cheap Estate Ammo or Whalley World Specials can cause a 5K level cleaning (if you haven’t lost those two tiny wrenches that came w gun.) even if you’ve only fired half of that volume.

    I installed Rich Coles Red Spring for light loads and it solved the problem. Don’t know if it was the disassembly & cleaning which cured it or the spring alone…according to Cole CS, a properly adjusted 391 will toss a shell 8-9 feet. Any more is unnecessary wear n tear and less and not enough gas to power action. Every gun is unique.

  2. Robert R Balicki says:

    I own a AL390 and have been using the Rich Cole springs for the past 10+ years using my gun on trap, upland and waterfowl game. They get a strong recommendation from me.

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