.300 Blackout Sub Sonic Cast Lead Bullets / Hardness

[Jamoy1993]

Okay, so i am at the point where I'm just about to get my Upper for my .300 blackout and now im looking at casting my own lead bullets for subsonics. The overall goal is to have a very cheap load i can afford to shoot 1 - 200 and not even blink at the cost, much like when shooting .22 LR.

I have a few hundred kilograms of lead at my disposal, and i also have access to a load of range scrap for free. The aim is to make a sub-sonic load for as cheap as possible. I worked out that i can load a sub sonic cast round for about the same cost as a .22 CCI Mini Mag (One can see the benefit to this)

I intend on running these sub sonic, 12.5 inch barrel with a moderator.

So i have a Lee 5R-230 .30 caliber mould that is specifically designed for sub sonic .300 blackout. I have cast a bunch of them in pure lead, but I am not sure if I will need to harden the alloy or not. I want to use un gas checked bullets as it will significantly cut on price as well.

I have graded some of my range scrap to be about BHN 12-15 (Pencil Method). Which seems about right. However, i am getting conflicting information on the web about the required hardness. Some folks say pure lead is just fine. Some say it needs to be a bit harder / gas checks ETC.

The first load recipe i will be using is straight out of Hornady and Cross Referenced with Sierras reloading manual:

Sierra:

Hornady:


I have put the data into GRT as best i can and it seems to settle out around 8 Grains of powder will get me the result i want:



So i understand when loading sub sonic you should start at the top and work your way backwards rather than starting at the minimum charge weight.

I understand that lead bullets may require a slightly different powder weight. I also understand that leading may be an issue, but i am hoping that i can buy some Antimony worst case to harden the lead if the range scrap / pure lead is not hard enough.

I also understand that i should do my load testing WITHOUT my moderator on to ensure they are stable in flight. I just bought the damned thing i don't want a baffle strike!

Things i will need to maybe invest in:

A lead hardness Tester (I dont like the pencil Method Too Much)

Things I DON'T want to have to do:

To use Gas Checks
To use lighter bullets for subs (will be higher pressure, requiring harder lead, and higher cost, also the powder required will risk double charges (N310 etc))
To have to buy jacketed bullets for bulk plinking ammo (For Supers. I will be loading ~ 125 Grains at 50 odd pence per shot, quite a bit steeper than 15 pence)

So, does anyone have experience with loading cast lead bullets that can give me some tips and advice? Is there anything i have overlooked?

 

[jthyttin]

Sounds good (like discussed in previous thread), I just want to point out that the following is not true regarding the higher pressure, no reason for harder lead either, so cost is not higher (theoretically speaking cost is lower if you have to source and melt less lead).

Things I DON'T want to have to do:
...
To use lighter bullets for subs (will be higher pressure, requiring harder lead, and higher cost, also the powder required will risk double charges (N310 etc))

Also pay close attention to burn characteristics of N110, since lead bullets are more "slippery" the burn rate might suffer. I have no personal experience in subsonics with N110 and lead bullets, have always used pistol powders regardless of bullet (exception being semiauto AK where cycling requires slower powder, but I don't use lead bullets in semiauto rifles).

 

[Jamoy1993]

Sounds good (like discussed in previous thread), I just want to point out that the following is not true regarding the higher pressure, no reason for harder lead either, so cost is not higher (theoretically speaking cost is lower if you have to source and melt less lead).



Also pay close attention to burn characteristics of N110, since lead bullets are more "slippery" the burn rate might suffer. I have no personal experience in subsonics with N110 and lead bullets, have always used pistol powders regardless of bullet (exception being semiauto AK where cycling requires slower powder, but I don't use lead bullets in semiauto rifles).

Aye, thank you for the input there. I do remember you saying. I thought it would be best to create a new thread specifically on this topic.

Makes sense on the friction of the lead vs copper jacket. I might have to settle for a bit more powder. On the other hand N110 seems to be the cleaner of the two powders in terms of burn rate as well. A lot of folks seem to say 120 is dirty even with casts, and GRT seems to suggest this as well, being pretty unsuitable for lighter loads, too.

Il make a bunch of soft lead and range scrap lead and see how they do then i guess. Thanks Jthy

 

[Tarquin]

I have been casting for decades for all sorts of calibers. One thing that is a constant is fit. Slug the bore.
Your cast bullets should be about 1 to 2 thou over your groove diameter. Leading is usually due to undersize bullets rather than hardness.
The pencil method is generally regarded as being "near as dammit" for hardness testing. I have never used it.
If you are around 15bhn that - IIRC - is about Lyman no2. Antimony apparently is tricky to work with. It gives off noxious gases when it oxidises. And too much will make the lead brittle.
If you have a supply of backstop lead and its from commercial bullets its probably going to be all you need. I have used loads of it over the years and its been fine.
I have just added linotype to firm it up for 303/7.5 bullets @ 2200fps.
Pure lead will probably be ok to 900fps. Over that you might have "slumping" with such a long bullet.
Powder choice may be key ultimately. I used a lot of N120 with cast and never found it to be dirty.
If you havent read it check out C E Harris article on reduced power rifle loads.
Check out 300 blackout on the castboolits forum.
Lever Gun Performance Studies is worth a read.

 

[Jamoy1993]

I have been casting for decades for all sorts of calibers. One thing that is a constant is fit. Slug the bore.
Your cast bullets should be about 1 to 2 thou over your groove diameter. Leading is usually due to undersize bullets rather than hardness.
The pencil method is generally regarded as being "near as dammit" for hardness testing. I have never used it.
If you are around 15bhn that - IIRC - is about Lyman no2. Antimony apparently is tricky to work with. It gives off noxious gases when it oxidises. And too much will make the lead brittle.
If you have a supply of backstop lead and its from commercial bullets its probably going to be all you need. I have used loads of it over the years and its been fine.
I have just added linotype to firm it up for 303/7.5 bullets @ 2200fps.
Pure lead will probably be ok to 900fps. Over that you might have "slumping" with such a long bullet.
Powder choice may be key ultimately. I used a lot of N120 with cast and never found it to be dirty.
If you havent read it check out C E Harris article on reduced power rifle loads.
Check out 300 blackout on the castboolits forum.
Lever Gun Performance Studies is worth a read.

The barrel i am getting is factory new. So im betting it would be .308 on the dot. Standard AR-15 300 BLK barrel. Ive measured the bullets ive cast and they come out at .310 - .311 do you think that would be good?

Il have a look at those articles you mentioned too. Thanks.

 

[Tarquin]

I would make up some dummy rounds using them "as cast" to make sure they chamber ok.
If so then simply tumble lube with thinned Lee Alox and you should be good to go.
Plain cast and aloxed good fitting bullets are usually ok for up to 1500fps give or take.
I am interested to see how you get on with this.

 

[Jamoy1993]

I would make up some dummy rounds using them "as cast" to make sure they chamber ok.
If so then simply tumble lube with thinned Lee Alox and you should be good to go.
Plain cast and aloxed good fitting bullets are usually ok for up to 1500fps give or take.
I am interested to see how you get on with this.

How does one thin Lee Liquid Allox? I take it you would use some sort of solvent?

 

[Tarquin]

Mineral spirits about 10%. Not all alox is the same consistency. Apparently lighter fluid works as well but I havent tried it.
Two thinned coats seems to work best. More even and dries quicker. Use an old baking tray with greaseproof paper.

 

[Jamoy1993]

Mineral spirits about 10%. Not all alox is the same consistency. Apparently lighter fluid works as well but I havent tried it.
Two thinned coats seems to work best. More even and dries quicker. Use an old baking tray with greaseproof paper.

Great, thanks for the tip.

 

[MilesW]

I worked out that i can load a sub sonic cast round for about the same cost as a .22 CCI Mini Mag (One can see the benefit to this)

You sure? At the current price of primers?

 

[Jamoy1993]

You sure? At the current price of primers?

Yes. Brass + Lead is Free, I get it from the club brass bin. I sometimes buy 1 shot GGG for 90 quid per 1000.

Powder: 8 Grains of N110 is about 6 Pence
((15432 Grains (1kg) / 8 Grains per charge) = £110 / 1929 Loads = ~£0.057 per load)

Primers: 1000 for 70 quid (Magtech) = £0.07 per primer

Total Cost Excl Brass = 13 Pence.

Including Brass (If i can get at least 5 Shots per brass)
9 Pence Per Piece
2 pence per use rounded up

Total Cost Including Brass = 21 Pence Total Initial Cost or 15 Pence per subsequent load.

 

[MilesW]

Yes. Brass + Lead is Free, I get it from the club brass bin. I sometimes buy 1 shot GGG for 90 quid per 1000.

Powder: 8 Grains of N110 is about 6 Pence
((15432 Grains (1kg) / 8 Grains per charge) = £110 / 1929 Loads = ~£0.057 per load)

Primers: 1000 for 70 quid (Magtech) = £0.07 per primer

Total Cost Excl Brass = 13 Pence.

Including Brass (If i can get at least 5 Shots per brass)
9 Pence Per Piece
2 pence per use rounded up

Total Cost Including Brass = 21 Pence Total Initial Cost or 15 Pence per subsequent load.

A bit more than the .22 I should think, but still pretty cheap. Should be a fun endeavour.
My plinker is a 25 cal and I am lucky enough to be able to buy off the shelf hard cast powder coated pills for about 6p each.

 

[Jamoy1993]

A bit more than the .22 I should think, but still pretty cheap. Should be a fun endeavour.
My plinker is a 25 cal and I am lucky enough to be able to buy off the shelf hard cast powder coated pills for about 6p each.

CCI Mini Mag is about 15 pence per shot, 15 pounds per 100. So after initial setup cost its damn cheap indeed!

Thats damn cheap. I wished i could just buy bulk milsurp 30 cal ball but there does not seem to be as much deals like that here. Its all in boxes of 100. Think the cheapest 30 cal i can get is PPU 123 Grain, which i will be loading as supers at about 30p per bullet.

What shoots the .25(ACP?)?

 

[MilesW]

What shoots the .25(ACP?)?

25-222 with a tiny amount of Trailboss. I bought 5000 of the pills.

 

[njc110381]

Adding antimony will up your hardness. I use ingots of printers type which is so hard it rings when you tap it. I've got enough here to spare you one if you struggle to find it. One bar would last you many thousands of rounds!

 

[Smellydog]

Lube your barrel with the same lube before shooting and don't clean it like you don't a 22.
You can also stick tiny wads to the bullet base to act as a firewall or gas check. Can be problematic with low case fills though.

As your casting a boat tail bullet you could deliberately add extra lube around the base and let the pressure do the rest.

 

[Jamoy1993]

Adding antimony will up your hardness. I use ingots of printers type which is so hard it rings when you tap it. I've got enough here to spare you one if you struggle to find it. One bar would last you many thousands of rounds!

The latest scheme i have is that Ive got 200 grams of Antimony and ordered 1kg of pewter. Ive got a spreadsheet to calc out what i need to mix to get Lyman #2 Type alloy which is apparently perfect for most rifle casting purposes.

Apparently 55 grams of Pewter + 50 Grams of Antimony + 1000 Grams of lead will equal ~ 5% 5% 90% Antimony/Tin/Lead Alloy Which is approximately equivelent to Lyman #2

I can do 4000 Grams of lead + 200 Antimony and 220 grams Pewter for ~ 4.4 kg of Lyman #2 which will yield approximately 300 ish bullets which will be plentiful for extended testing before i buy more Antimony, which i will end up buyng a full kilogram which is about 80 quid. The pewter is about 20 per kg. So 1000g Antimony + 1100 Grams Pewter + 20 kg Lead = ~1500 Bullets (Wont be the only thing i would cast but it will be for now) Which will work out to a total cost of ~ 7 Pence per bullet

Im going to make a small batch of bullets in soft, Range scrap (~ 10 BHN) and Custom Lyman #2 Like (~16 BHN) and Im going to drop some of those in Water which will apparently harden them even further up to 22 BHN and see what the groups and velocities are.

I appreciate the offer, i might have to strike you up on that when i figure out what im doing!

Lube your barrel with the same lube before shooting and don't clean it like you don't a 22.
You can also stick tiny wads to the bullet base to act as a firewall or gas check. Can be problematic with low case fills though.

As your casting a boat tail bullet you could deliberately add extra lube around the base and let the pressure do the rest.

If i can get away with softer lead then i would prefer it as it will be cheaper. However i do not want to use any sort of checks as i will be running a moderator i cannot take apart so i dont want to have bits of fiber and crap rattling inside.

I will definately be well coating them in Lee Liquid Allox.

Also do you mean i should clean it like a .22 or I should not? As in should i let the barrel be dirty?

What if im wanting to shoot Supers through it?I'm

 

[Smellydog]

You want a coating of lube in the barrel so don't clean.
If you want to use lead at super you'll be fine but switching between lead and jacketed bullets at super will be a tall ask!

 

[njc110381]

That sounds pretty technical! I just note what percentage by weight of a bar I need to achieve good results and then continue with that mix. I could do you a whole ingot for £80, they weigh closer to ten kilos than one!

 

[Jamoy1993]

You want a coating of lube in the barrel so don't clean.
If you want to use lead at super you'll be fine but switching between lead and jacketed bullets at super will be a tall ask!

Hmm, I'll need to see what I can do. If I can get them to shoot in an un-lubed and as close to "normal" operation as possible, I will be happy. I'm not wanting to dedicate it to only shooting lead subs.

That sounds pretty technical! I just note what percentage by weight of a bar I need to achieve good results and then continue with that mix. I could do you a whole ingot for £80, they weigh closer to ten kilos than one!

Thats a lot of hard lead for the price!

Is it 12% antimony? Linotype?