doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Ammo Pressures?

I am trying to learn about ammo pressures and what is "safe" and what is "good" for use in SXS shotguns.

I talked to RST and know their shells are in the low 7,000. William Larkin and Moore also has ammo in the low 7,000. area. Someone mentioned to me that Winchester AA ammo-even the low recoil variety is around 10,000. has someone published the pressures for the various factory loadings?

I also don't know how to interpret or think about these numbers. I gather they are pounds per square inch? How does one interpret proofs marks and translate that into PSI terms? How does one need to think about PSI numbers versus their own particular shotgun(s).

I have two AYA boxlocks of 2010 vintage (12 and 28 gauges). I feel comfortable shooting any 2 3/4" shells through them. Obviously recoil is more pronounced with "high brass" loads. I don't know how to think about dram equivalents and pressures other than simply assuming that higher dram equivalents means higher pressure. But, doesn't that depend on the powders used in the loads and their burning curves?

I am in the process of purchasing a 1930's English boxlock. It's a 2 1/2" 16 ga. Thus, my factory ammo choices will be limited. I know that Gamebore ammo has higher velocities. Is there published pressure information for their loads?

I also do not understand the correlation between "safe" but higher than desired for shotgun longevity. Is the issue shooting the gun "loose" before it's time, or concern for what will happen to the old wood in the stock as a result of the recoil forces on it? Or, all of the above? With Damascus barrels, is the concern mainly focused on the barrels integrity?

Are there any good reference materials I should obtain? I didn't find what I was looking for after searching this forum. I may not have searched correctly. Are there any threads here that you can link me to?

Any thoughts and advice will be appreciated. Thanks!

Here you go. Reported pressures for some loads at the bottom
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/preview

The short version is under "Shotshells and Shooting" here
http://lcsca.clubexpress.com/content.aspx?page_id=274&club_id=43784&sl=827060842

Lots of questions RTW. Smarter guys than I can answer them all here. but I'll take a stab at some preliminary answers.

To begin, your modern built AYAs will be fine with whatever you want to shoot. Personally, even in modern built guns I try to go for low recoil and seem to get about the same results as with the big recoil stuff.

The 2.5 English boxlock will be another matter. Depending on age mostly you have to worry more or less about pressure damaging the frame, recoil breaking down the wood. I'd stick to low pressure (RST) 2.5" loads in that gun if I were you.

Damascus barrels are whole different kettle of fish. Many of us here admire them and shoot them as well. The shooting of course is dependent upon barrel condition. That would include wall thickness, dents, bulges, and pitting. I usually do not shoot Damascus barrels in poor condition with any load...Geo

The old British Game Load for the nominal 2 1/2" chamber of 3 tons per Sq inch translates to right at 9,000 PSI as recorded by modern Piezo Electric crystals. This is "Max Chamber" pressure.

One thing to keep in mind is recoil is "NOT" directly related to max chamber pressure. It is related to the max weight which is ejected from the barrel (shot, wads & powder) & the velocity at which they are ejected.

Max chamber pressure applies to how much the camber walls are capable of withstanding. Personally if the chamber walls are "Too Thin" or in too bad a condition of holding 8,000 PSI, that gun is simply a "Wall Hanger".

Stock troubles are related to recoil, not chamber pressure. Recoil as stated is related to oad IE matter ejected & speed of ejection. If you want to protect old wood use a lighter shot load &/or a lower velocity. Hope this helps but do feel free to ask further questions you may have.

Rtw,

RST makes a lot of loads. What RST load are you referring to that is 7000 psi?

I have an email from RST saying their 2.5" 1oz load is 6200 psi.

Thanks,
Ken

Here is a compendium of RST pressures based on product that I have compiled from either this forum or direct inquiry with RST over the past 2 years. Please verify with RST as products, propellants, etc. can change over time:

**ALL 2 1/2" 12 GA

Paper Fibre Wad 1oz 6100
Lite Roll Crimped 1 1/16
*Plastic 6100
*Paper 5900
MaxiLite 1oz. 5700
Falcon Lite 7/8oz. 5400
Falcon Ultra 3/4oz 4400

I shoot the 2 1/2 inch RST 3/4 oz ultra lite and 1 oz max lite in my 6 lb guns and the felt recoil is really soft. Shooting my reloads at the same speed and weight with published pressures of 7000 psi or so yields quite a bit more felt recoil. I am a big fan of the RST's.

Jim

Thanks for all the great info.

I enquired about their 2 1'2" 16 ga loads. Was informed that the Lites were around 7,200 and the A5's around 7,400-7,500.