Question on Chamber Length

[Austin W Hogan]

Bill; I would really like to find a solid pre 1920 reference to this long shell in short chamber pattern theory. I think Askins the elder alluded to it but did not verify or explain it.
The bore jig I used to measure the Super Fox allowed me to make some quantitative measurements about this. One of my own "competition" guns is 136683 that dates from 1906 and was made to measurements by DuBray. It shoots beautifully tight, round patterns with both barrels. It is chambered 2 3/4 inches; the front of the forcing cone has a long taper ending at the barrel diameter of .740 inch at 6 inches from the breech, and one choke is more parabolic than like Oscar's "OGEE". I have a VHE with btfe and monte carlo, no safety 170789 , 32 inches that shoots similar round patterns. It is also 2 3/4 chamber with the forcing cone taper meeting the bore of .738 at 5 inches from the breech, and again a more parabolic choke in the left (full) barrel. A third 32 inch PH (207489) also reaches .738 at five inches, and the left barrel choke begins at .740 five inches back from the muzzle with a more parabolic than ogee taper. These dimensions do not duplicate the Super Fox, but the forcing cone taper and choke taper is of the same form.
These three guns tell me either that these owners sent their guns to Becker, or that King knew how to produce these patterns with forcing cone and choke profiles that did not involve jamming the case mouth into the forcing cone.
I have some "new" primed 3 inch ten gauge paper cases from two makers that have never been loaded or fired. They measure 2 7/8 inches precisely. I would like to find some unloaded twelve ga cases to measure.
The Super Fox has beautifully tapered chokes and forcing cones. The chambers measure .788 - 792 at 2 5/8 from the breech. The most common plug type chamber gauges are .792 wide. I did not measure the Super Fox with a blade gauge, but it may have measured 2 5/8.
Multiply fired modern 2 3/4 cases measure 2.66 +/-. Squaring the ragged mouth would shorten them a little. Were paper 2 3/4 cases also 2 5/8? We need some unfired cases to measure.

Best, Austin

[10ga Hammer]

"Were paper 2 3/4 cases also 2 5/8? We need some unfired cases to measure."


Austin, I just took a quick look at some unfired paper hulls I have stashed away and found a 12ga paper Federal "Monarch" measures 2 5/8, a 10ga "Leader" 2 5/8, and a 16ga "New Rival" 2 9/16. HTH, Bob

[Bill Murphy]

Austin, first you wanted a reference that guns were made for longer shells than the chambers. I gave you those references. Now you changed your mind and want a 1920s reference for how such guns pattern with long shells. You can find anything you want in Askins' articles because he was in the word selling business. One month he would write that short shells in long chambers throw great patterns, next month they will throw bad patterns. I just read an Askins article from 1916 where he tests shot containers. In the lengthy article, he doesn't really reach a conclusion or compare his patterns to patterns without using shot containers. Why did he do that. Simple, to sell another article next month, in which he may actually reach a conclusion. Or maybe not.

[J.B. Books]

A few thoughts. If indeed Parker chambered guns 2 5/8" for 2 3/4" shells and it was an industry standard;

How long was that practice carried on by Parker?

How long was that practice carried on by any other Maker?

Why did they change?

If they changed to meet "standards" did Parker or Remington lengthen chambers upon request or as part of any repair?

If Parker was still in business would they lengthen chambers on older guns or not? (I realize this is pure speculation).

Finally, because this is hot button topic I wonder if there may be those among us who think lengthening chambers is a good idea or OK but don't bring it up because they don't want what they might consider to be unecessary harsh critcism from the board?

If it doesn't matter if you don't do it, and the gun is a "shooter" and not unique, does it really matter much if it is done?

A Trojan 20 is a fine gun, I like mine, but it's a Trojan and I don't think lengthened chambers undercut overall condition/price if it's nice and original otherwise.

[Austin W Hogan]

Sorry Bill; I am really looking for a solid citation about this irrespective of who prepared it. I think that the experimental results of measurement of Parker competition guns, and Super Foxes are in direct conflict with the idea that long cases in short chambers produce better patterns than short chambers and short forcing cones. I would really like to find the original, and continuing publications that present the short chamber theory.

Anyway; I look forward to seeing you and Kevin Saturday.

Best, Austin

[Bill Murphy]

I think gas sealing was always the reason for 1/8" shorter chambers. I don't think that better patterns were ever a part of the equation. Pete, I don't disagree that lengthening chambers is a benign act on a less than collectable gun. However, no one can argue that it doesn't cost money, and doesn't sometimes lower the price of a gun when offered to a serious collector. I would rather have the extra steel in the area of the forcing cone than a couple of hundred pound feet of pressure. The very small rise in pressure has been proven empirically, the cost of drilling out barrels and the related shipping expense doesn't need to be proven. It is there.

[J.B. Books]

Hi Bill, not trying to argue just asking food for thought questions.

What about my other questions? Especially did Parker change to 2 3/4" 12 ga and if so when? Did Parker or Remington at any time ever lengthen or recommend lengthening chambers? Is there any documentation?

What does Turnbull, DelGrego, Kearcher etc. recommend today?

2 5/8" to 2 3/4" is not much of a jump but 2 1/2" to 2 3/4" is at least in my mind.

If Parker had survived into the modern times would they recommend leaving chambers alone of bring them to SAAMI standards (even if it was just for liability reasons)?

Seems to me we have a gamut of high condition orginal high grade guns to solid but very worn knockabouts. Altering a museum quality firearm is probably not a good idea. Lengthening chambers and forcing cones could be a good choice on a low grade shooter where performance matters more than collectibility

Shotguns have evolved and knowledge of how they perform has improved. I believe it is a given today that shotgun performance is improved through back boring, long forcing cones and chambers sized to current shells.

I have wondered if P Brothers thought it would be easier, cheaper and less trouble to market 2 5/8" chambers for 2 3/4" shells than to retool and consider modifying all existing guns to meet the changes occuring in the early part of the 20th century.

The cost of lengthening chambers is there but it is not significant to what the average price of gun is including Trojans.

Just my .02 Pete