Staging up a .410 subsonic load....

[luvbus]

I am hand loading some .410 carts to use in my Pedretti Hushpower.

 

I have a suitable recipe but the table suggests the silencer type & length will have an effect on results.

 

As such I would like to stage up a number of loads to the point of becoming super sonic to obtain the optimum subsonic load.

 

What would a reasonable step up in grains/grams be for each load in a .410? (i.e. 0.2, 0.4, 0.5, etc.)

 

T.I.A.

 

Rich

[sitsinhedges]

I am hand loading some .410 carts to use in my Pedretti Hushpower.

 

I have a suitable recipe but the table suggests the silencer type & length will have an effect on results.

 

As such I would like to stage up a number of loads to the point of becoming super sonic to obtain the optimum subsonic load.

 

What would a reasonable step up in grains/grams be for each load in a .410? (i.e. 0.2, 0.4, 0.5, etc.)

 

T.I.A.

 

Rich

 

Have you got a chrono to check the velocity

[Andy H]

What are the components are you wanting to use powder/primer/wads/shotload.

[luvbus]

Have you got a chrono to check the velocity

 

No, I do not have a chrono, I realise it would be useful but ultimately it's the crack at the sound barrier I am trying to find & keep below so I would have thought I could get away without one.

 

Cheers,

 

Rich

[luvbus]

What are the components are you wanting to use powder/primer/wads/shotload.

 

I have 3" 'Lyvale' cases, CX50 primers, Vectan SP3, 15mm cork wads, 3mm overpowder wads, #7 lead shot, overshot cards & a RTO tool.

 

I have a recipe for a 21g load using H-17 wads using 12 grains of the above powder for a velocity of 1018fps. I was advised the cork wad could be substituted as it would give lower pressures. I should then stage up the charge until a 'crack' can be heard. I understand I should end up with a powder charge of about 13.3 grains (i.e. 12 grains / 0.9 = cork wad charge (13.3 grains)).

 

Pressures will still be well within gun limits as this is a subsonic load (I have a similar recipe with 14 grains of powder to give 1109fps with the H-17wad).

 

The thing I forgot to ask when buying supplies was what is a reasonable weight to stage up each test load to reach the sonic crack, I do not want to go at it like a bull in a china shop with the .410 as I understand a small increase can have a big effect but I don't want to waste time increasing in too small an increment.

 

What do you experienced guys recommend?

 

Cheers,

 

Rich

[Guest cookoff013]

that increase is nearly 10% extra powder, i`d be really cautious, as this is a magnum .410 (as denoted by the huge shot charge.)

i dont have the data, but 1/2 grain increase should be enough.

 

never assume the pressure by the velosity. by the nature of ballistics, large shot charges are used to keep the pressure up. but with this load the shot charge is at near the maximum for 410.

 

thats one of the issues with normal shotgun powders. back off the powder charge too much and they dont burn right (squib load)

use too much of a high pressure powder and a normal shot charge and the pressure is high -maybe too high?

 

i`d say 1/2grain increase..

[Andy H]

I see you are using one of Ian's recipe's , That load giving 1018fps at 2.5 meters from the muzzle but gives 1063 fps at the muzzle , the speed of sound is 1126fps at 20degree's C and 1106fps at 10 degree's lower so that load does not give you much room to experiment less than 40 fps at lower temperature,

If you work a load up so that you just get the crack and then back it off until no sonic crack the pressures will be ok but to much spread in velocity will result in the odd cartridge going supersonic when it cools down a bit ,Not something you want if working around animals etc.

The pressures for the two loads you mention are 405 bar for the supersonic load and 314 bar for the subsonic load proof pressure for a 410 shotgun in 3" should be 900 bar.

Edited October 11, 2010 by Andy H

[Floating Chamber]

Take care! It's dangerous to reduce the charge in a small bore, especially with its 'tall' shot-column. Pressure is the killer. You can't feel it.

 

F.Y.I Ian has a CSBO load with 8.5 grains pushing 19.5grams! Vo @ 2.5m is 987 fps.

Edited October 11, 2010 by Floating Chamber

[sitsinhedges]

In my experience stated velocities that accompany recipes can vary greatly in reality and if you are expecting to suddenly get a huge sonic crack at 1125 fps you are likely to be disappointed. You really need to chrono your loads to have any real idea what they are doing.

 

When I was experimenting with .410 the recipes I used produced very erratic loads with wide variations in velocity. Because the barrel tended to be dirty suggesting a poor burn I carefully added another grain of powder bit by bit. This squared everything up and became consistent but I would have struggled to know what was happening without a chrony because everything seemed the same by feel, sound etc.

[Floating Chamber]

From Nobel Sport Handloading Manual, page 48:

 

Regarding Slow-burning powders.

 

'Everything else being equal, increasing a charge of a given powder inevitably creates an increase in pressure. However, in certain circumstances, reducing a slow burning powder by approximately one third can cause overpressure and even a detonation effect that can result in a destroyed gun.'

Edited October 11, 2010 by Floating Chamber

[unclemicky]

Can I just say thanks for sharing guys , this thread is really interesting as I'm going to start to reload carts for my 410 as I use far more of these than 12g

[Andy H]

Can I just say thanks for sharing guys , this thread is really interesting as I'm going to start to reload carts for my 410 as I use far more of these than 12g

Welcome to the world of custom cartridge stuffing, All i can say is do not stray far from the path of proof tested loads.

[luvbus]

Take care! It's dangerous to reduce the charge in a small bore, especially with its 'tall' shot-column. Pressure is the killer. You can't feel it.

 

F.Y.I Ian has a CSBO load with 8.5 grains pushing 19.5grams! Vo @ 2.5m is 987 fps.

 

Ian does not have CSB0 and will not have any more coming, EOL! I wanted CSB0 as it would have worked for both .410 & steel in 12g.

 

Dividing the powder charge by 0.9 increases the charge, in this case from 12 grains to 13.3333 grains.

 

What I plan to do is load 5 cartridges at each interval increasing by 0.5 grains starting at the 12gr/21g subsonic load recipe and ending at the 14gr/21g supersonic recipe. The pressure listed for these recipes are 314.4 bar & 405.57 bar respectively, both of which are well below a listed recipe for 2.5" 12g load which comes out at 473.04bar.

 

Am I missing something in the big picture? I would rather ask the experts than plough on in ignorance....

 

Cheers,

 

Rich

[luvbus]

In my experience stated velocities that accompany recipes can vary greatly in reality and if you are expecting to suddenly get a huge sonic crack at 1125 fps you are likely to be disappointed. You really need to chrono your loads to have any real idea what they are doing.

 

When I was experimenting with .410 the recipes I used produced very erratic loads with wide variations in velocity. Because the barrel tended to be dirty suggesting a poor burn I carefully added another grain of powder bit by bit. This squared everything up and became consistent but I would have struggled to know what was happening without a chrony because everything seemed the same by feel, sound etc.

 

I thought a chronograph was of limited use with shotguns and in particular small gauge due to the length of shot string & accompanying wads, cards, etc.

 

If I continue this reloading lark I am sure I will add one to my 'quiver' but at the moment I am without!!

 

The area I am using the Hushpower in is quite enclosed and makes the 'crack' quite noticeable, when I have used it in more open areas it becomes much less so but that is not what I bought the gun for.

 

Ta for the input.

[luvbus]

that increase is nearly 10% extra powder, i`d be really cautious, as this is a magnum .410 (as denoted by the huge shot charge.)

i dont have the data, but 1/2 grain increase should be enough.

 

never assume the pressure by the velosity. by the nature of ballistics, large shot charges are used to keep the pressure up. but with this load the shot charge is at near the maximum for 410.

 

thats one of the issues with normal shotgun powders. back off the powder charge too much and they dont burn right (squib load)

use too much of a high pressure powder and a normal shot charge and the pressure is high -maybe too high?

 

i`d say 1/2grain increase..

 

Thanks for that, somehow I have skipped past two posts and missed the info (mental note not to do that agin with regards reloading!!)

[luvbus]

I see you are using one of Ian's recipe's , That load giving 1018fps at 2.5 meters from the muzzle but gives 1063 fps at the muzzle , the speed of sound is 1126fps at 20degree's C and 1106fps at 10 degree's lower so that load does not give you much room to experiment less than 40 fps at lower temperature,

If you work a load up so that you just get the crack and then back it off until no sonic crack the pressures will be ok but to much spread in velocity will result in the odd cartridge going supersonic when it cools down a bit ,Not something you want if working around animals etc.

The pressures for the two loads you mention are 405 bar for the supersonic load and 314 bar for the subsonic load proof pressure for a 410 shotgun in 3" should be 900 bar.

 

You have the same info I have and have given me the same advice as Ian gave, problem was he didn't say & I didn't ask by what weight should I increase each load when staging up between the two loads!!

 

Cheers all, I think I am getting there now!!

 

Rich

[Downforce]

On 11/10/2010 at 21:13, Andy H said:

I see you are using one of Ian's recipe's , That load giving 1018fps at 2.5 meters from the muzzle but gives 1063 fps at the muzzle , the speed of sound is 1126fps at 20degree's C and 1106fps at 10 degree's lower so that load does not give you much room to experiment less than 40 fps at lower temperature,

If you work a load up so that you just get the crack and then back it off until no sonic crack the pressures will be ok but to much spread in velocity will result in the odd cartridge going supersonic when it cools down a bit ,Not something you want if working around animals etc.

The pressures for the two loads you mention are 405 bar for the supersonic load and 314 bar for the subsonic load proof pressure for a 410 shotgun in 3" should be 900 bar.

Appreciate this is a really old post but how to calculate/measure the pressure?

I recently read another post that suggested it was beyond the capabilities of a simple calculation (talk of rocket ship formulae)

As posted elsewhere I am looking to create a 410 load that will have optimum range, so looking at larger shot (00/000 buck) but with a UK S2 legal 410 load consisting of 5x 000 Buck we are talking about c21g and 45mm of shot column probably needing a 76mm cartridge so this thread is interesting - particularly the point about reducing powder causing an increase and potential excessive pressure. Obviously I am looking for the load to be inherently safe and I'm not specifically concerned with it being sub-sonic or not.

D