I was looking at Hodgdon's site hoping to find low-pressure data for loads above one ounce, no, and looked at Remington STS hulls cut to 2,5 and there is one 1 ounce load at 7200psi. I thought I would check to see how that load translated to a 2.75 hull but found that it doesn't. I guess I may assume that to make the RemSTS 2.5 loading the shell must be trimmed and that is the only load Hodgdon tested so that is all they want to publish, but what I find curious is that they use UNIVERSAL powder in it but Universal is not used in any Rem STS 1 ounce 2.75 loads. Would anyone have any idea how that works? Just some added information, if you take the 7200 psi RemSTS load and substitute a WInAA 2.5 hull the pressure is 8500psi.

That load is with a AA12R wad, which is a short wad designed in prehistoric times for the 1 3/8 oz. and 1 1/2 oz. short magnum 12 ga 2 3/4" shell. With lighter payloads it gas seals poorly, thus the low pressure result with 1 oz in the 2 1/2" hull. It's a lousy wad and will make a lousy load. Forget it.

Universal is on the slow side for 1oz. 12 gauge. Similar to Unique. They can't test and publish everything, and Hodgdon's data is on the old side at least much of it.

They do publish this for a Federal Gold Medal and 1 1/8 oz.

Winchester Super Hcp 19.4 Ched. 209 Fed. 12SO 6,400 PSI 1,145

My concern is that it would fit in the hull. I use the CB 2100 which is a clone of the 12S0 and it works perfectly with ONE OUNCE and a powder of similar bulk as 19.4 of SH. I only use the wads intended for straight wall hulls with the Federal shells.

Not everything these guys publish is actually practical. It may take a 12S3 to make this even work.

A few days ago, last I checked, Ballistic Products had the Cheddite 209 primers in stock and Grafs had Super Handicap.

EDIT: Now that I think about it, I bet the above mentioned load would work in a TOP GUN hull. Use the newer ones with the plastic base wad.

Mr. Jones. Thank you for the reply. I didn't notice the wad was an AA12R which I happen to have 3 and a half bags but never thought I'd have a use, and guess I still don't. Buying, or trying to buy Universal powder just for that load isn't practical. I make a 2&3/4 inch 1 ounce load now with Clays that if the data is accurate suits. It just struck me odd they would come up with a load using a powder they don't use in other common 12 ga loadings just because the hull is 2.5. Well, I guess they know what they are doing. Thanks again.

Which is what I thought when I started loading 40 years ago. I know better now....

I suspect the origin of the load you cite was that they wanted to offer 'something' before the general availability of 2.5" Cheddite hulls and Gulandi wads.

First what is your pressure goal? 5,000/1 ounce, 6,000/1 ounce or 7,000/1 ounce. Second what hulls do you have to work with. Third what wads, primers and powder. Once you give someone those inputs they might be able to get you into loads you can use. What you listed is not a great combination, workable, but not great. Then load up and have them pressure tested. Never trust information freely given over the internet. A single minor mistake could be a real issue.

I have over 30 powders, seven different types of primers, a pickup load of different wads, tens of thousands of hulls in everything from 10 to .410 and years of accumulated reloading manuals and recorded data and I still trust, but verify, by having "real" new stuff not tested by a known source tester. Printed stuff, from decades ago I take with a small grain of salt and anything off the internet with a small bolder of salt. In honesty, I have taken loads for 2 3/4" and loaded in 2 1/2" using roll crimps with fairly good results but that is not really very safe.

Thinking out loud, have you looked at some of the straight walled euro hulls or Federal hulls? They are cheap, or free for pickup, at most shooting ranges. Straight wall is a bit easier to find low pressure loads for than a tapered hull like STS or AA hulls. Get a large number of them first. Then start doing your load research. Find one and then let it become your default low pressure loads. I would also look at a Federal Hull trimmed down to 2 1/2", with AA wad and Clay's powder. Load up six of them and send them out to test. Once you have found what you want load only that load in that hull so from that day forwards you will know every hull loaded of that type is a low pressure load, safe in all your guns.

I second what KY Jon said about utilizing pressure testing sources, like Tom Armbrust and others. It totally eliminates guesswork.

How would using 2.75” data in 2.5” reloads be potentially unsafe if components are unchanged? Using the Hardin crimp with an overshot card should have minimal effect on pressure. I say that without any testing data to back it up but has anyone had reloads tested that utilize the Hardin crimp method?

Hartin crimp, with a "t'.

Developed by a member here.

I just thought the use of a powder not used in any other 12 gauge load, to make a 2&1/2 inch 12 gauge load was surprising.

Please explain how the “Hardin Crimp with a T” makes using 2 3/4 data in same hull with the same data save roll crimped from 2 1/2 would raise pressures or invalidate the load?

I have been of the belief that 2 3/4 load data that fit in 2 1/2 lengths hulls were ok, am I wrong, and if so why?

Unless you test the loads you don’t know if it makes any difference at all. I do know that over crimping, crimping a shell too deep, will increase pressures. That I tested and pressure shot up over 1,000psi. We think, not proven for certain, that cutting a shell down and roll crimping a load lowers pressure slightly. But again unless you test them you really don’t know. I’ve never tested a Hartin load for pressure so won’t hazard a guess about any effects on pressure. Testing a single load is simple and inexpensive so there are good reasons to know for certain. If you were working up a dozen different loads money might be a factor.

I take a different view point. If you're reloading at 7500psi which many of us do for the older guns, then a 1000psi or so isn't going to mean very much. A couple of years back I called Clay Busters and ask if it was ok to sub in different wads [ for short shells ]. I had told him I was loading around 7500psi. He said he couldn't answer officially without testing, BUT he wouldn't be afraid to sub in a different wad if it was from the same manufacture with the same over powder base. All you're changing is the length of the cushion part. The part where the powder sits, it's length or diameter, hasn't changed one bit so why would pressure change ? If you're going to insist it does, is it enough to make a difference ? I've reloaded for shotguns since 1970 and shot and reloaded for Damascus barreled shotguns since 2005. In all those years of shooting 2 3/4, or 2 1/2 or even shorter shells like 2" I have never sent a shell in for testing. Sometimes I go to a roll crimp [ or a Hartin crimp at times ] and don't give it a second thought. Yes, too deep a crimp of any kind will increase pressures. That's easy enough - don't crimp too deep. My 10ga guns are all 2 7/8 and there is no data for them. It's simple enough. Use 12ga low pressure data with a 10ga wad. The bigger chamber [ larger diameter ] will produce less pressure. Just use a little common sense and you'll be ok.
We're just shooting shotguns at the lower end of the pressure curve. You want pressures, shot rifle or pistol.

You do understand how a shotshell works, right?

After ignition, when the propellant thermally decomposes into gas, it encounters a moveable obstruction. The wad acts as a piston, which drives the shot load up the barrel. The 'cushion' section is just that, a collapsible section of the wad that increases the initial area available for gas expansion.

The peak pressure is reached before the shot even moves from it's initial position.

Contrast 2 extreme variations, one the red AA wad, the other the gray AA style wad designed for 7/8 ounce loads. Put the short wad in a short shell, put the longer wad in a standard shell. The area available for initial gas expansion with the longer wad and case looks to be about THREE TIMES as much with the standard case and long wad.

How in the world can pressures be even close to identical?

Change the wad seal to shell wall, like using a wad for a tapered hull in a straight wall hull and it will alter pressure. Use a wad with a shorter crush section, in place of one with a longer one and it will change pressure. Primer substitution will alter pressure, in some examples a lot. If you are really just trying to find a generic safe load, some could suggest a starting point, but the only way to know what you have is to test them.

If you are way under maximum pressure and do not care about real pressure, or real velocity, then that might be good enough. Many low pressure loads are also low velocity as well. You need to figure out what you are trying to achieve, low pressure with low velocity like 1050-1100, or low with 1200 fps or greater. And sometimes the hulls, wads, powders and primers you have on hand just will not get you want you are after so change your inputs by selecting others. Right now hulls are the easiest one to change and powders are the hardest.

The area available for the powder going off is from the base of the wad to the base wad itself and the diameter of the shell. The cushion area of the wad cushions the shot, and not designed for expanding gases. It's so the shot doesn't get deformed. Do we know how stiff a wad with a shorter cushion area is than one with a longer cushion area ? NO. The cushion area allows for a good stack height with different powders. I still stand by my statement. I called Claybuster and they confirmed my belief. Even if I agreed with you, do you really think the cushion area collapsing a mirco second a little quicker is going to make a dangerous situation ? Why would anyone reload at maximum pressures ? We are in a double gun forum, so I'm not trying to cycle a auto, or worried about a little unburnt powder. It's all gone after the next shot. Why do you think I don't care about REAL pressure or velocity - whatever that means. I have 15,000 primers, 32 pounds of powder, 10,000 wads, and short on shot - only 10 bags. The primers are Win - a mild primer, powder is 700X and Promo, a little 7625 and PB. I've been reloading for over 50 years and don't need to be told if I sub in a wad from the same manufacture, with the same designed base, if it has a longer or shorter cushion it's going to change pressures enough to be concerned about. It won't change squat. Most of my 12s have 2 5/8" chambers. For over 17 years 2 3/4" shells have been going in those Damascus barrels with no problems. Sorry if I came off a little upset. You load what you want and I'll do as I want.

SG, if you're using the same powder, the same amount of powder, and the wad is seated against the powder, then you have the same area for initial gas expansion. I don't care if you put a 5 inch wad in front of it, it makes no difference. The wad weighing a little more figures in the formula along with the shot when calculating recoil but that's about it.

Alliant publishes two 7/8oz. loads, consecutively on the page, using two different wads.... the AA12SL with a 20ga. card in the shotcup and the AA12L.

The sole difference is the length of the crush section.

The pressure difference is 600psi, which for this load is 8.3%.

There's a difference, if you think so or not.

From what I have experienced over the last 30 years of shotshell reloading is that different powders do much different things with that Crush sections depending on primer. Pressures can be all over the place. So anyone reading this probably should stick to same powder, primer and hull if you dare swap wads. Also sticking that load in a shorter crimped (2.5” standard fold) hulls can cause pressure swings based on what I just mentioned. Much more serious than a deep crimp and we have all seen what that can do to pressure.
Be safe my friends.

I'm sorry I said it would make no difference. All I was trying to say it wouldn't make enough difference to worry about. Pretty much the same thing you just said. A whole 600psi.