3.5" Chamber vs 3" Chamber Pattern

[Sniffer]

I am not gonna lie, what goes on inside the barrel of a shotgun with "Forcing cones" etc is black magic to me.

So as someone who is looking at a new purchase and considering guns with both 3" & 3.5" chambers does it make any difference as to how they shoot 2.75" shells?

Does the extra chamber length make any tangible difference as to how they shoot (to be clear I will be using birdshot mostly, decent amount of slugs and some buckshot all 2.75").

My current gun (VM with unofficial 3.5" chamber) seems to manage just fine with all of the above.

 

[struff55]

the choke is what determines how it shoots

 

[Sniffer]

the choke is what determines how it shoots

Makes sense being at the "business end" but all other things being equal (same choke etc) does the chamber size make any difference?

And a second question - does a longer barrel in a shotgun just mean added velocity (like a rifle)?

 

[struff55]

for the most part it does add fps but pattern density kills birds not so much fps it's sort of the same as a rifle bullet you need x number of pellets to strike the bird that is how the energy is caculated

 

[Painkillers]

Makes sense being at the "business end" but all other things being equal (same choke etc) does the chamber size make any difference?

And a second question - does a longer barrel in a shotgun just mean added velocity (like a rifle)?

Brobee will be along soon, but it is fair enough to say that yes; s longer barrel departs more velocity but there are diminishing returns on that. Brobee did a very in depth analysis of how much velocity is lost with shortened barrels and it is substantial. If I recall correctly, an 18" barrel is the shortest one can go without losing significant velocity. It therefore stands to reason that a barrels length will have a point of not giving anymore benefit. Now, whether that is 28" or 32" idk...but there only ever is so much propellant and once it's burned...it's all you're going to get.

3" shell...more powder and load.
3.5" shell...more yet.

You won't have any trouble firing 2.75" shells in a 3.5" chamber, but you may have ejection problems (stove piping) as the receivers ejector will be set further back in a longer receiver.

 

[waldo54]

I have an A400 extrema with a 3 1/2" chamber, the gun will never see a 3 1/2' shell as long as I own it though, for waterfowl I shoot 2 3/4" and 3" they cycle and eject just fine, and yes they kill birds with the same authority as a 3 1/2" shell just way less bang and $$, the choke is what patterns the shot, the chamber has no real bearing on the pattern, different ammo will pattern differently using the same choke but usually not enough to notice.

 

[Sniffer]

Brobee will be along soon, but it is fair enough to say that yes; s longer barrel departs more velocity but there are diminishing returns on that. Brobee did a very in depth analysis of how much velocity is lost with shortened barrels and it is substantial. If I recall correctly, an 18" barrel is the shortest one can go without losing significant velocity. It therefore stands to reason that a barrels length will have a point of not giving anymore benefit. Now, whether that is 28" or 32" idk...but there only ever is so much propellant and once it's burned...it's all you're going to get.

3" shell...more powder and load.
3.5" shell...more yet.

You won't have any trouble firing 2.75" shells in a 3.5" chamber, but you may have ejection problems (stove piping) as the receivers ejector will be set further back in a longer receiver.

Good info, thank you.

I get the barrel length diminishing returns argument - have seen it on PCCs and 22LRs. To be clear I feel that the 1301 Pro Comp with the 21" barrel is the best all around fit for me but that gun only has a 3" chamber (I doubt I will run 3" or 3.5" ammo through it, will be pretty much 2.75" only). The 28" barrel is a little on the long side for sure but the 3.5" chamber has advantages from a magazine capacity aspect.

The 1301 Pro Comp has a 3.5" action and from what I can tell seems to run fine with 2.75" ammo.

 

[Sniffer]

I have an A400 extrema with a 3 1/2" chamber, the gun will never see a 3 1/2' shell as long as I own it though, for waterfowl I shoot 2 3/4" and 3" they cycle and eject just fine, and yes they kill birds with the same authority as a 3 1/2" shell just way less bang and $$, the choke is what patterns the shot, the chamber has no real bearing on the pattern, different ammo will pattern differently using the same choke but usually not enough to notice.

Perfect, I figured that would be the case but it is good to hear that.

The A400 Xtreme Plus Synthetic is the model I am considering. It has the Kick-Off Mega & Kick-Off3 with Soft Comb which they state reduces recoil by 70% so it should be very soft shooting with 2 3/4" ammo. Beretta gave the 1301 Pro Comp another Kick-Off version that reduces recoil by 40% from memory so not as extreme but maybe the Kick Off Mega is overkill for 2 3/4"?

How soft does your shoot?