M4 - 2 port 4 port barrels

[Milspec]

I'm just trying to clarify.  When people talk about 2 port/4 port this is in reference to the gas ports in relation to the the pistons correct?

We're not talking about actual conventional porting which mitigates recoil/muzzle rise.  I searched for barrel picks to compare the two but I couldn't find anything on the interwebs.

[Vertigofirearms]

4 port barrels are exceedingly rare. I don't even know if they make them anymore.

[StrangerDanger]

Correct. When you look down the barrel of the current production M4, you will see two ports. One port for each ARGO plug. On the 4 port models, each ARGO plug had two ports about half an inch from each other. 
 

I haven’t seen one of these 4 port barrels in years. My burnt bronze M4 came with one when I bought it in 2004. It was the first release of the 11703 models with the neutered receiver extension. Within the first outing, I snapped a piston in half firing 2 3/4 buckshot. Took Benelli a month or more to send me a new piston after mailing them the broken one. 
 

Then for another 7000 rounds, the shotgun performed okay until I noticed that the bolt carrier was getting stuck when pulled to the rear of the receiver. Closer inspection found that the face of the bolt carrier was mushroomed where the pistons make contact. The carrier was so badly deformed that it was binding inside the receiver. The 4 port barrel was battering the carrier to death.

 

Trip back to Benelli at this point at my expense. Benelli replaced the entire bolt carrier group, barrel assembly, pistons, ARGO plugs, and handguards with 11707 model parts. 
 

Now at 17,000 rounds, no more issues have been encountered.

 

 

[HughCA]

On 7/5/2020 at 7:22 PM, StrangerDanger said:

Correct. When you look down the barrel of the current production M4, you will see two ports. One port for each ARGO plug. On the 4 port models, each ARGO plug had two ports about half an inch from each other. 
 

I haven’t seen one of these 4 port barrels in years. My burnt bronze M4 came with one when I bought it in 2004. It was the first release of the 11703 models with the neutered receiver extension. Within the first outing, I snapped a piston in half firing 2 3/4 buckshot. Took Benelli a month or more to send me a new piston after mailing them the broken one. 
 

Then for another 7000 rounds, the shotgun performed okay until I noticed that the bolt carrier was getting stuck when pulled to the rear of the receiver. Closer inspection found that the face of the bolt carrier was mushroomed where the pistons make contact. The carrier was so badly deformed that it was binding inside the receiver. The 4 port barrel was battering the carrier to death.

 

Trip back to Benelli at this point at my expense. Benelli replaced the entire bolt carrier group, barrel assembly, pistons, ARGO plugs, and handguards with 11707 model parts. 
 

Now at 17,000 rounds, no more issues have been encountered.

 

 

Hi late to the game - so are you suggesting 4 port M4's are not as reliable as 2 port ones?

[StrangerDanger]

14 hours ago, HughCA said:

Hi late to the game - so are you suggesting 4 port M4's are not as reliable as 2 port ones?

The 4 port barrels are extremely rare. They were only released on the 2004 era 11703 model. The 4 port barrels were notorious for beating up the bolt carrier to the point that it would mushroom out the bolt carrier where the pistons impinge. I had one, and the bolt carrier mushroomed out so bad that it would get stuck when retracting the bolt carrier to the rear. Benelli warrantied it and gave me a 2 port barrel thankfully.

The 4 port would probably perform better with low recoil ammunition. But if you fed it any high brass, you'd start tearing it up.

[HughCA]

On 11/2/2023 at 2:30 AM, StrangerDanger said:

The 4 port barrels are extremely rare. They were only released on the 2004 era 11703 model. The 4 port barrels were notorious for beating up the bolt carrier to the point that it would mushroom out the bolt carrier where the pistons impinge. I had one, and the bolt carrier mushroomed out so bad that it would get stuck when retracting the bolt carrier to the rear. Benelli warrantied it and gave me a 2 port barrel thankfully.

The 4 port would probably perform better with low recoil ammunition. But if you fed it any high brass, you'd start tearing it up.

Really appreciate the further explanation - I am likely only using 00 buckshots and slugs on them, so I guess 4 port version is not for me. I am only curious since there is a local guy selling one quite cheap and round count is only 8. Feels like a good deal, until it's not. Thanks!

[StrangerDanger]

I'd definitely avoid since it would likely cause damage that would be out of warranty with Benelli. Assuming they found out you had a 4 port barrel in there.

[bambihunter]

HughCA, you could verify visually which port type it is. Also, if it is a REALLY good deal, perhaps you could buy it, then buy a replacement barrel. I'm not sure if there'd be any demand on the 4 port due to its rarity to Benelli collectors (which I am one, but not interested in the barrel). Just a thought, but remember barrels often run for $500 so it'd have to be a really good deal.