In the past I have relied on RST for most of my vintage shells. Just for ease. I haven’t actually called them, but the site is usually out of everything I use. My stock is about gone….

I reload for Trap at times, I have various powder handbooks, from the manufacturers but, there isn’t anything in that 5k psi range.

What are some good manuals out there that have a good selection of low pressure recipes these days? From Precision Reloading? Or off Amazon? Lyman?

I’m looking for 12ga 2.5” loading data.

Thank you!

Go to the Hodgden and Alliant websites. There are a number of good lower pressure loads listed. 7/8 oz 12 gauge loads using ClayDot powder are around 6,000 psi. Good luck though finding components

lymans shotshell hand book has lots of load formulas that fall in the 6 to 7000 psi range...

can data for 2 3/4 hulls be used for 2 1/2 " hulls?

and if not, why not/

Ballistic Products reloading manual has various loads for short shells.

For low pressure 12 loads I bought up a large stock of PB and 800X, both are hard to find as they are discontinued. Clays, International or Tightwad come to mind as possible powders. Alliant powders seem just a memory these days with only a few seen in scattered places. I bought 8 pounds of Unique a few weeks back but had not seen any in two years.

It comes down to what components you have available. I keep a ridiculous number of powders on hand, along with six different primers, many different wads and enough different empty hulls to fill a pickup truck completely full. And still I come up short on too many combinations. Locate what you can buy, then go to Hodgdon and Alliant online reloading guides to see what works. Also Trapshooters.com has a reloading section with a decent number of tested and verified loads for currently available powders, primers and wads. Does you no good to find the perfect load which uses Remington Primers when none are available and last seen were north of $100.00/1,000.

Also you might need to be flexible in what low pressure load you are after. 1 ounce/ 1,100-1,150 fps works for me while other might like a 7/8 ounce load for clays in the 5-6,000 psi range. Do watch many older published loads were in lup not psi and that makes a real difference.

Where is the line drawn between low pressure and high pressure? I recall a discussion years ago when the late Miller explained that the pressure curve was more critical in the barrel and was as important, if not more critical, as the peak pressure number. Seems I recall his referring to an old graph comparing pressure curves along the barrel length of various loads. I've seen loads which were listed as "low pressure" having psi in the mid 7K psi; others in the 5-6k psi range. Gil

smokeless loads that duplicate black power pressures could be considered as low pressure?

Gil is absolutely correct. To attain a common velocity two different pressures still have to generate similar energy. One can attain that in a very short distance in front of the chamber. The other, a lower pressure load, stretches out its energy creation further down the barrel. So, if I’m shooting an older gun with thick chambers but tapers quickly I choose a higher pressure load, keeping the stress in the strongest portion of the barrel. If the chamber is marginally thin, as many very early breechloaders were, then I’ll opt for a slower powder to distribute pressures into the bore. Common sense.

I think these were on doc drews site

I prefer to load smokeless powder using fibre wads and finding recipes for low pressure loads has been a challenge. I'm wondering about the relationship in pressure if I were to take a load listing a plastic wad and interchanged it with a fibre wad. Would I get more or less pressure or would I be going into the dark realm of loading where I shouldn't be?

Pressure peaks within or slightly past the chamber. Ten inches down the barrel everything is under 1,500 psi, at 5” you are just over 2,000 psi. So your highest pressures are within an inch of the chamber, dropping off very quickly there after.

I spent a lot of mental energy figuring out safe loads for all my doubles. I shoot low pressures to protect the stock not because I think my barrels are too weak to withstand the pressures. Ultra thin barrels are not going to be shot by me. Terms like proof and service pressure help define loads to use. Black powder loads give you a safe working pressures if you need more guidelines. Most are in the 5-6,000 psi range.

My 12 bore, low pressure loads, run from 5,000 to 7,000 psi. Anything in between works well and I feel safe shooting them in all my guns. I have had less consistent results using sub 5,000 psi loads so bump it up to 5,000 plus. In 20 bore I top off at 8,000 psi but could go 8,500psi. Pressures run higher in small bores. I shoot 2 1/2” in 2 1/2” chambers but accept others safely shoot 2 3/4” in their guns. It is just so easy to trim a bunch of hulls and load shorter ones, plus I enjoy the process.

Sorry. Not paying attention

Hunter Arms Co. Pressure Curve dated June 10, 1929, from the McCracken Research Library, Buffalo Bill Center of the West (found by Gary Rennles) and used by permission
http://library.centerofthewest.org/cdm/singleitem/collection/WRAC/id/8149/rec/107

The digital image is part of the Winchester Repeating Arms Company Collection but includes a notation “Hunter Arms Co”. WRAC was acquired by Western Cartridge Co. Dec. 22, 1931, so it is impossible to know if the curve was generated by Winchester, Western, Hunter Arms, or (very possibly) the Burnside Laboratory of the E.I. du Pont de Nemours & Co.



PROOF LOADS
Loaded with FFFg black powder. Shot presumed to be No. 6.
Pressures were measured by crushers (LUP - Lead Units Pressure) and modern piezoelectric transducer measurements would by 10 – 14% higher
F - 10g 2 7/8” 9.5 Drams with 2.36 oz. shot = 16,000 psi
A - 12g 3” 8.265 Drams with 2.187 oz. shot = 17,250 psi
G - 12g 2 3/4” 7.53 Drams with 2 oz. shot = pressure not recorded
B - 12g 2 3/4” 6.5 Drams with 1.687 oz. shot = 14,200 psi
C - 16g 2 9/16” 6.5 Drams with 1.687 oz. shot = 13,750 psi
It seems likely the ‘B’ 12g and ‘C’ 16g labels were switched
D - 20g 2 3/4” 5.74 Drams with 1.5 oz. shot = 14,625 psi
E - .410 2 1/2” 2.377 Drams with .624 oz. = 15,625 psi

MAXIMUM STANDARD LOADS
1” peak pressures
H - 12g 3” ‘Record’ 1 3/8 oz. shot presumed 1275 – 1295 fps = 13,250 psi
I - 12g 2 3/4” ‘Field’ 1 1/4 oz. shot presumed 1330 fps = 10,750 psi
The label ‘J’ for 28 gr. Ballistite and ‘K’ for 3 1/2 Drams DuPont Bulk appear to have been switched on the pressure curve graph. Dense Ballistite clearly generated greater pressure than DuPont Bulk.
K - 12g 2 3/4” 1 1/4 oz. 28 gr. Ballistite = 12,900 psi
J - 12g 2 3/4” 1 1/4 oz. 3 1/2 Drams DuPont Bulk = 10,000 psi

The pressure curves essentially meet at 5” at 7000 psi; at 10.1” 2625 psi (DuPont Bulk) to 3000 psi; at 15.5” 2000 psi; at 22.1” 1500 psi

Jon, my understanding is that recoil, not chamber pressure, is what damages stocks. Velocity, a factor in recoil, is independent of pressure. A low pressure load of 6000 psi shooting 1 oz. at 1300 fps in a 100 year old double is far more likely to damage wood than a higher pressure load of 8000 fps shooting 1 oz. at 1050 fps. Gil

well, well then, an so on, etc...

if max pressure is around 7" from the breeches, why then does no one else seem to care about minimum barrel wall thickness gudelines in front of the chambers...

cept for yours truly...

and how does one measure individual shotgun recoil...

presume it is measured in foot pounds per ?

Come on Ed, you know how to measure recoil.
I've been shooting Damascus barreled SxSs since around 2000. I try to keep my reloads around 7500psi which is fairly easy to do with 3/4, 7/8 or 1oz loads under 1200fps. That will also satisfy Ed. There are very many loads in my Alliant handbook for 7/8oz loads [ it's what international skeet and trap loads are limited to ] using Clay Dot, Promo, Red Dot, American Select any where from 6000psi to 8000psi, many in the lower range. You want to use fiber wads, go right ahead. You're just going to lower the pressures given with plastic wads. The fiber doesn't seal as well.
A number of years back Sherman Bell tried to blow up 20 Damascus " wall hangers " given to him. He used Remington proof loads of around 18,300psi. NONE of them even cracked. He then took a Parker to 30,000psi before it let go. He also tested longer shells in short chambers. Pressures went up about 500. I shoot 2 3/4" shells in all my 12ga guns, many have 2 9/16" chambers. I think the OP is worrying too much. I'm not saying all guns are safe. Use your own judgement.

I would go to Alliants and Hodgdons web sites, find their phone number, and give them a call asking for one of their free handbooks. I find them much easier to use then the web sites. You'll also get more info than Lymans hand book.

"if max pressure is around 7" from the breeches..."
Is that a typo ed? and a shotgun "breech" is not plural.

Every published pressure-distance curve, including the one I posted, shows the peak pressure to be 1-2" from the breech, even with 'Progressive Burning' DuPont Oval.

GLS, you are correct, low pressure, modest payloads, modest velocity do all play a part in protecting stocks and not stressing thinner or weaker barrels at the same time. Many old barrels are well able to withstand anything reasonable you put in them. 100 year old stocks might not. I just find a ounce, 1100-1200fps, at 5,000-7,000 will do everything I need it to do. I am not pass shooting geese at 70 yards with a short chambered 12 bore. I have a short chambered 10 for that.;).

I shoot a lot of Sporting Clays, Skeet, Trap and late season Dove with guns suited for modest, low pressure, low velocity shells. To easy cartridge identification all my Federal “short” shells are 1 ounce, number 7 1/2, 1125fps @5,600psi. My Remington load is 1 ounce 8’s at 6,500psi and 1150 fps. The Winchester hulls are 1 ounce, 9’s @ 1125fps. B&P are 7/8 ounce, number 8 1/2’s, 6,500psi @1250 fps. Every load was found on Hodgdon website. It takes time to gather different powders and wads but once done you can make enough ammo for months to years of use. I am not stressed by component shortages or ammo choices not being what they once were.

I load on a Spolar,in large batches of several hundreds to a couple thousand at a sitting. In a single sitting I can load enough to last for a long time and just keep stuff in buckets until I get around to boxing things up to stack on my ammo shelves. So whenever I pick up a loaded “short” shell I know automatically what is in it and that it is safe for every gun I own. If it is 2 1/2” it is safe for everything and I can just select different loaded shells to get the correct shot size for what I want to shoot. The B&P work great on Skeet with real crushing ink dots in tight chokes. It took a bit of planning but now I am never in doubt what I have on hand and have several thousand shells loaded for quick selection and fun use.

While 2 1/2 data is the ideal, I have found that using 2 3/4 data rolled crimped into 2 1/2 length hulls works well. Sometimes I discover the load does not fit, but most times it does.

I simply stick to sub 8,000 PSI data as a rule of thumb. I have found Hodgdon’s website a decent source and there. I found their 1 1/8 loads for federal paper hulls and Remington Fig 8 wads and International powder good. I also like their Green Dot, PB, and SR 7625 data, though finding the later powders if you do not already have it is hard.

Thanks guys! Lots of good info here! Yeah I was wondering about roll crimping to 2.5” length a 2 3/4” load.

Roll crimps work well. Also a Harkins crimp which is a shell cut down to 2 1/2" and has a shot card placed over the shot and then a regular crimp using the slightly shorter crimped area to seal the card over the shot. The card prevents an open center area on the crimp, the crimp seals the over the shot. In many loads I have enough room to simply shorten the shell and crimp in a normal fashion or substitute a slightly shorter wad to reduce stack height. Like a shorter red AA wad for the regular AA. I had one load tested and the pressure was just slightly higher that original load and it all fit perfectly in a 2 1/2" shell with a normal crimp.

I am not too picky about powders, but, in my opinion, a 7/8 ounce load at 1200 fps for any 12 gauge gun is not going to damage it, end of story. These guns have had a lifetime of 1 1/4 ounce loads without damage.

I am surprised no one has referenced the DGJ 2021 article "Taking the pressure off" by Ross Seyfried. He worked with Hodgdon Ballistic to develop updated loads to those by Bell and Armbrust earlier in the DGJ. Seyfried/Hodgdon provides lp loads for 10, 12 and 16 gauge. I called Hodgdon and they verified the components, details and accuracy for these loads.

A pressure-time curve stolen from Seyfried's article. Part of the application is that it is not hard to reproduce black powder pressure curves with today's smokeless powder options