Thread: Does reducing the powder charge for a 12 gauge slug safely reduce projectile speed?

A friend I have loaded some 12 gauge slugs in the past has asked me to reduce the fps by about 400 fps.
Being a noobee, I assiduously followed the manufacturer's loading books instructions and am uncertain how to achieve this nor do I fully comprehend all the unfortunate side effects which may occur.

These are both sabot slugs (using a WAA 12 wad with trimmed petals.) Lyman 525 gr and Lee 1 oz which I have loaded according to these manufacturer's recommendations, being:

Lyman . Lymans 5 th edition Shotshell Reloading handbook page 380....28 grains AP70N 1400 fps
Lee. Loading instructions supplied with their Lee 1 oz slug mould.....29 grains AP70N 1450 fps

Please, there are three issues upon which I seek your advice / opinions...........and of course any extras you may feel necessary.

1...Will just reducing the powder load result in a slower slug speed? I would suspect so, but by how many grains to achieve the 400 fps speed reduction? I can of course do a range of powder loads but am uncertain of the range variation, i e three loads, starting first at 13 grains, then increase each by 3 grains
I realise that this is probably going to be subsonic but think that although not being told so, this is what he wants.

2...Will reducing the powder load be an invitation for severe loss of projectile speed and control? I would expect so if too much of a powder reduction was made. Is that inevitable when any reduction is made or is there a lower threshold before it becomes troublesome?
3...Apart from the possibility of a reduced powder load not completely emptying the barrel and leaving an obstruction within, what other are undesirable side effects could arise?

Your advice would be appreciated.

So you want to make sub-sonics? Waiting with great interest at the answers..

Reducing powder charge will naturally reduce velocity I sometimes make mouse fart loads ( 12gr 700x and 1 oz shot)for kids to use. They require some fiddling as the powder column is shorter and affects the overall length and have found them easiest to cut the petals off and roll crimp.
These are shot loads by the way and havnt been chronied but they have piss all recoil and sound like a champagne cork. As the weight of shot is the same as your slugs and the bearing area on the bore is approximately the same results should be similar.
It actually takes very little force to push a wad down the bore the choke being the only real constriction, I know this from experience but don't ask me how.

Originally Posted by Marty Henry

Reducing powder charge will naturally reduce velocity I sometimes make mouse fart loads ( 12gr 700x and 1 oz shot)for kids to use.............It actually takes very little force to push a wad down the bore the choke being the only real constriction, I know this from experience but don't ask me how.

Interesting. Thank You and I'll add that to my information resource.

As for "don't ask", I won't but I fear I already know and that is one reason why the recipient of these outcomes is using a single shot ,break open 12 g.

Reducing powder charge will naturally reduce velocity I sometimes make mouse fart loads ( 12gr 700x and 1 oz shot)for kids to use. Std load is 18 grains 700x so mimms calculation appears a good guide. They require some fiddling as the powder column is shorter and affects the overall length and have found them easiest to cut the petals off and roll crimp.
These are shot loads by the way and havnt been chronied but they have piss all recoil and sound like a champagne cork. As the weight of shot is the same as your slugs and the bearing area on the bore is approximately the same results should be similar.
It actually takes very little force to push a wad down the bore the choke being the only real constriction, I know this from experience but don't ask me how.

What is a "Norwegian A12?"

Originally Posted by norsk

What is a "Norwegian A12?"

A lazy and totally incorrect "Kiwi" naming of one of your countryman's products.

This stupid boy dropped the - and substituted 12 for tec as it is attached to a Sulun A-12 Benelli clone. Sorry @norsk I trust this below, clarifies the product.

Is a SG subsonic more accurate? Thinking, if a SG slug exits the bore subsonic, it won't experience subsonic-->transonic-->subsonic transition wobbles.

find a round ball of correct diameter...and be aware,and make sure to tell you mate...shotgun slugs BOUNCE like buggery if hit something hard,slowing them down will make it more so....many years ago I nearly shot myself with 12ga solid after shooting big ram through head inside a woolshed,the projectile went around the walls and rails and stopped on decking 12'' from my leg...needless to say didnt do it again...big rams are plurry hard work to tip over for a teenager,so shooting them first was humaine on us both.

lyman #5 says DO NOT reduce by moree than 5% in the buckshot/slug text....

AP-70N appears in my old paper ADI book 3rd edition november 2000
cowboy shotshell data all loads shown are 1200fps at slowest,
winchester compression case.win 209 primer WAA12 22grn AP-70N

with remington case all the same but 21.5grns for 1255fps

thats once n 8th loads.... SEEMS YOUR ap70n is for the heavy end of loads....

Originally Posted by Micky Duck

AP-70N appears in my old paper ADI book 3rd edition november 2000
cowboy shotshell data all loads shown are 1200fps at slowest........thats once n 8th loads.... SEEMS YOUR ap70n is for the heavy end of loads....

As you say, "Cowboy loads," which nowadays seem to favour Trail Boss.

My current task is for 1 oz to 1.2 oz slugs . For your interest, I have a copy of a reply from ADI powders in response to another user's query for subsonic loads and it reads as follows..


"Here are figures supplied to me by the Ballistics Lab at ADI Australia using ADI AS30N


12 Gauge
Case: Winchester AA compression formed (Should be the same in the new Winchester case)
Primer: Win209 or Fiocchi 616
Wad: WAA12 (1-1/8th wad)
Powder: ADI AS30N/Hodgdons Clays
Shot: 1-1/4oz Lead Shot


11 grains = 851 fps @ 5970 psi
12 grains = 910 fps @ 6915 psi
13 grains = 944 fps @ 8610 psi
14 grains = 985 fps @ 9840 psi "

Subsonic loads with similar shot weights however greatly reduced powder charges. It is from these that I create loads for my Spanish Laurona sbs and started with when seeking subsonic loads in the Norwegian silenced Sulun Tac 12 semi .

you could be pushing poop uphill till you source another powder perhaps....

I can tell you now,when that slug was bouncing around woolshed walls n rails I WAS FAIR CRAPPING MY DAKS.....NOT recommended.

Interesting to remember that both the English Snider and Martini Henry projectiles finally settled up with a weight of 480 grains, basically the same weight as the modern day Lee 1 ounce key slug.

There is little to fear from them bouncing around as the user has a neat taget rack consisting of a hanging heavy carpet to which the tagets are attached. The projectiles don't bounce, they go straight through and end up in the earth behind the rack.