October
S M T W T F S
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
Who's Online Now
9 members (Ken Georgi, bigblock, 5 invisible), 108 guests, and 13 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums10
Topics36,801
Posts520,779
Members14,212
Most Online462
Aug 5th, 2016
Previous Thread
Next Thread
Print Thread
Page 2 of 2 1 2
Joined: Mar 2002
Posts: 7,199
Likes: 144
Sidelock
**
Offline
Sidelock
**

Joined: Mar 2002
Posts: 7,199
Likes: 144
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.

Joined: Oct 2004
Posts: 1,812
Likes: 4
Sidelock
**
Offline
Sidelock
**

Joined: Oct 2004
Posts: 1,812
Likes: 4
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.

Joined: Feb 2003
Posts: 3,989
Likes: 28
Sidelock
**
Offline
Sidelock
**

Joined: Feb 2003
Posts: 3,989
Likes: 28
Originally Posted by Paul Harm
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 ?

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?


"The price of good shotgunnery is constant practice" - Fred Kimble
Joined: Mar 2002
Posts: 7,199
Likes: 144
Sidelock
**
Offline
Sidelock
**

Joined: Mar 2002
Posts: 7,199
Likes: 144
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.

Joined: Oct 2004
Posts: 1,812
Likes: 4
Sidelock
**
Offline
Sidelock
**

Joined: Oct 2004
Posts: 1,812
Likes: 4
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.

Last edited by Paul Harm; 08/01/22 12:35 PM.
Joined: Oct 2004
Posts: 1,812
Likes: 4
Sidelock
**
Offline
Sidelock
**

Joined: Oct 2004
Posts: 1,812
Likes: 4
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.

Last edited by Paul Harm; 07/21/22 03:14 PM.
Joined: Feb 2003
Posts: 3,989
Likes: 28
Sidelock
**
Offline
Sidelock
**

Joined: Feb 2003
Posts: 3,989
Likes: 28
Originally Posted by Paul Harm
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.


"The price of good shotgunnery is constant practice" - Fred Kimble
Joined: Jan 2020
Posts: 366
Likes: 14
Sidelock
Online Content
Sidelock

Joined: Jan 2020
Posts: 366
Likes: 14
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.

Last edited by Jtplumb; 07/28/22 12:43 PM.
Joined: Oct 2004
Posts: 1,812
Likes: 4
Sidelock
**
Offline
Sidelock
**

Joined: Oct 2004
Posts: 1,812
Likes: 4
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.

Page 2 of 2 1 2

Link Copied to Clipboard

doublegunshop.com home | Welcome | Sponsors & Advertisers | DoubleGun Rack | Doublegun Book Rack

Order or request info | Other Useful Information

Updated every minute of everyday!


Copyright (c) 1993 - 2022 doublegunshop.com. All rights reserved. doublegunshop.com - Bloomfield, NY 14469. USA These materials are provided by doublegunshop.com as a service to its customers and may be used for informational purposes only. doublegunshop.com assumes no responsibility for errors or omissions in these materials. THESE MATERIALS ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANT-ABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. doublegunshop.com further does not warrant the accuracy or completeness of the information, text, graphics, links or other items contained within these materials. doublegunshop.com shall not be liable for any special, indirect, incidental, or consequential damages, including without limitation, lost revenues or lost profits, which may result from the use of these materials. doublegunshop.com may make changes to these materials, or to the products described therein, at any time without notice. doublegunshop.com makes no commitment to update the information contained herein. This is a public un-moderated forum participate at your own risk.

Note: The posting of Copyrighted material on this forum is prohibited without prior written consent of the Copyright holder. For specifics on Copyright Law and restrictions refer to: http://www.copyright.gov/laws/ - doublegunshop.com will not monitor nor will they be held liable for copyright violations presented on the BBS which is an open and un-moderated public forum.

Powered by UBB.threads™ PHP Forum Software 7.7.5
(Release build 20201027)
Responsive Width:

PHP: 7.0.33-0+deb9u11+hw1 Page Time: 0.050s Queries: 33 (0.029s) Memory: 0.8444 MB (Peak: 1.8991 MB) Data Comp: Off Server Time: 2022-10-02 13:44:19 UTC
Valid HTML 5 and Valid CSS