Clarification details
Hello, Fred.
I am going to start by stating that I am not against chamber modification, which I believe I posted earlier, and as for forcing cone rework, my special super-long forcing cones are not like what you have probably seen before, and the smoothness of the finish is typically better than the bore of normal barrels.
I'll bet if you tried one of my forcing cones, you'd turn your nose up at any other style after that.
I am not wanting to argue, since most times that regresses to a back and forth:
'TIS
'TISN'T!
"TIS!!
'TISN'T!!!
And where does that get you?
I am definitely stating that the slight chamber length difference cannot and is not going to make any monumental pressure or force changes that others use as horror stories to get somebody scared into having work done, since the innumerable examples out there of uncracked frames (of all types, including that 1100 I mentioned) belie the case that the chamber length is the cause.
If I was to surmise the most likely cause, it is the fact that the front outer corner of the ejection port is the thin section that may be excessively wiggled from the shock of firing, and mainly due to looser fit of unadjusted barrels may cause extra pounding shock not present in other designs.
There may be a case for this in an easily-understood situation: shooters that care for their guns, and keep them maintained (barrel adjustments tight and not shot until repaired, if loose) would be more likely to spend the money to get a chamber/forcing cone job vs. Mr. Lickpenny not doing either at a gunsmith- barrel adjustment refit OR chamber/forcing cone.
I'd be surprised if you haven't already pointed that likelihood out at some point in time around here.
By the way, have you seen the cracks that sometimes develop at the inside corner of the action bar groove and sometimes into the corner of the interrupted mag. tube threads? There's a couple of nice thin spots waiting to be overstressed. Cracks that develop there from loose barrels can reduce frame rigidity and allow excess flex that culminates in ejection port edge cracks.
I'm afraid that the information posted referring to the last entry of
"1858"
needs some math revision, referring to the length of crimp laying in the cone, and so forth.
A 3" shell that is 2-9/16" unfired becomes- guess what- that's right: 3 inches, not just another 3/16" long.
I'm sorry that I need to be the one to point out repeated errors of an elementary nature, but since nobody else spotted them, and wants to use that information to make a judgment call about my posting relevance, there's the rub.
Sorry.
Here's the real reason, regardless of the math errors:
a shell of 2.3" unfired (standard 2-3/4" length) has the shot touching the chamber wall (through the hull) at about 2.15-2.2", and will have at least 3/8" free run before hitting the forcing cone, see? (this example, not a normal 2.75" chamber)
How much run will a 3" shell (unfired shot edge at 2.45") have? Under 1/4" in this specific example.
Point 2: 3" shells are loaded to a higher spec. pressure max. than 2-3/4" shell max., I believe.
Naturally, we are not even taking into account the ejection port length being for 2.75" max., either.
As for slugs being shot in unmodified chambers, that is probably better since the slug has less chance of mis-alignment from a long jump to the bore. Lead slugs are usually a bit undersized, really soft lead composition, and easily deformed. The exception to this would be in an offset chamber/forcing cone situation where the slug is already getting abused unevenly due to the variance of impact, since the longer cone side would naturally have to push harder against that side of the slug to guide it into the off-center bore from the chamber position.
I wonder why nobody has taken the position that if a slightly longer chamber reduces pressure, why not have a 3" chamber to REALLY reduce the pressure, or maybe even 3.5" chamber?
I'm going overboard, but you see the point.
This, of course, does not take into account the extra deformity that must happen to the lead projectiles from sliding down an oversize hole and (after gaining more speed than would be present in a standard un-lengthened chamber) then being subjected to the squeezing action of the forcing cone funnel.
Trade-offs are always present.
Of course, some might point out that lengthening the chamber extends the thinnest part of the chamber wall further into the section of the barrel that may (in at least some instances) be already tapering in exterior dimension.
See, I do cover a lot of bases with my explanations.
Now I'll ping it back to you, Fred.
Good time discussing things, wouldn't you say?
BTW, Fred, did you read the articles at my website?
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