My suggestion is to 1: find the chamber length 2. shoot hells that have 1 ounce or less loads at a moderate velocity such as RST. I would have the gun checked out by a competent gunsmith for wood or mechanical problems to include barrel wall thickness. I would further suggest that you might want to learn how to load your own shells to meet your needs.

Mark,

What year did this chart come from DuPont? Just curious.

Frank

"Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics" by Wallace H Coxe; E.I. du Pont de Nemours & Co., 1933.

http://pic20.picturetrail.com:80/VOL.../404232424.jpg

Validated by Sherman Bell "Finding Out for Myself, Part VI, Smokeless vs Black", in The Double Gun Journal - Summer 2002, p.19

that 6 frame must be a 8 ga with that barrel weight of 8 lb 10 ounce...could be a ten ga but not many tens built with that much barrel weight..thow i think thomas s 10 ga barrels weigh over 9 lbs...lordy i like the monster guns...sorry i got off track... charlie

For Greg's question of what causes "detonation" in a barrel:

From a US Army Technical Manual:

b. Deflagration. If a particle of an explosive reaches a temperature at which the rate of decomposition becomes significant, deflagration or spattering of the particles from the surface occur prior to decomposition. At a characteristic temperature, heat output is sufficient for the reaction to proceed and be accelerated without input of heat from another source. At this temperature, called the ignition temperature, deflagration, a surface phenomenon, begins. Gaseous reaction products flow away from the unreacted material below the surface. Deflagration of all the particles in a mass of finely divided explosive occurs almost simultaneously. In a confined space, pressure increases, which, in turn has the effect of increasing the rate of reaction and temperature. The final effect of deflagration under confinement is explosion, which may be violent deflagration or even detonation. In the case of low explosives, such as loose black powder and pyrotechnic compositions, only violent deflagration can take place. Nitrocellulose propellants (smokeless powders) can burn, or if confinement is sufficient, deflagrate so rapidly as to detonate.

Mark, thanks for posting that from the US Army Technical Manual. I still wonder if a very low pressure load can cause detonation which can damage a barrel. Hopefully the published low pressure 7/8 and 1 ounce recipes utilizing PB powder that generate 4300 to 5100 psi that I'm using in my damascus guns aren't adding any additional risk.

Jent, Frame size is a "2" as in the photo you attached. Also some other numbers on bottom of barrel left to right: D with a smaller 4 above, then a small c, then 4 with small 6(as if 4 to 6th power), then a 3. The barrel lug has a 2 on the bottom. I take it the "2" is the actual frame size. What are the other numbers?

Bottom of receiver has the serial number with 3 above and D below.

Although the serial number would say it is a 1906, the inside/bottom of the reciever has a date of PATD. Aug 15, 1905

Ross the large 4 with a small 6 is the unstruck barrel weight. 4lbs 6oz after assembly before cleanup, with the forend attached. The D stands for damascus steel. You are correct that the 2 is frame size. The small c and the 3 are most likely craftsmans stamps.
I have a twin to your gun. RST shells are the way I go for loads as I dont yet have the resources to reload my own. I also have 2 10ga. A damascus and a Twist that I use RST ammo in. Enjoy your Parker.