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just got my hands on a Howa 20" in 7.62x39 and wanting to cook up some sub sonic loads for it. Hornady do the 225gn projectiles so thinking of using those but not sure on what type of powder to get (or what's available...) also open to use other weight pills if anyone has any recipes i could start with?
Watching with interest… just had some 151g casts arrive and haven’t reloaded at all for this rifle
I'll do a big post when i get more time. Ive just spent a couple of weeks playing with the 255gr subx pill (heavily modified) in my 7.62x39 ruger.
Heres a big red hind i shot Saturday @ 25m in public Bush.
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The 225gr Hornady bullets are .308 ones right? I would skip those and start off with the 255gr SubX like Roarless20 has. They're the correct diameter for the bore. Bonus they're 30gr heavier.
A bit of AR2205 or pistol powder should be all you need for them in a bolt action.
Should be able to find a fast pistol powder - Red Dot is a good one if you can find it. TrailBoss is obviously the default, but you might struggle to find it in sufficient quantity.
As far as loads, the 7.62x39 is a lot smaller in volume to something like the .308Win - so usually would require less powder all things proving correct. My 20" .308 is using 9.5gr of Red Dot with a 170Gr Sub-X pill at 1040FPS if memory serves correctly. I think for the similar speed in the smaller case with a similar weight of pill it was in the region of 6gr.
As far as loads with the fast pistol powders, you can't really go too light in grains of powder and cause a safety issue with ignition of the powder and pressure - the safety issue is not having enough pressure to clear the pill out of the barrel. If you jam a pill in the barrel and fire another - it usually isn't good. The usual advice is to start at the highest load recommendation without the suppressor on and work back until you have reached the velocity you require and have confirmed stability. Then check the velocity with the suppressor fitted as you can end up gaining a bit of speed.
When loading with fast powders, you can run into pressure issues with too much powder as the pressure curve is very steep (like vertical) then quickly dropping away - which is quite different to standard rifle powder loads which come up to the max pressure comparatively more slowly and then drop away in more of a curve. Too much fast powder is possible instant bomb. Within standard loads like a '08 length case it's safe - for reference there is a 'standard' reduced load using Red Dot of 13gr and standard weight pills (150-180gr) which is good for about 1600fps or so depending on the pill and I've never heard of any dramas with that amount.
I never had much luck with subs until I started crimping the necks lightly, then everything got a lot more reliable and groups tightened right up.
Only subs (and some supersonics) I've ever bothered with have been cast, propelled by shotgun powders red dot, blue dot and unique. I tried trailboss when it came out
but found it extremely dirty and no improvement over what I was using. A lump of lead works pretty well if it's in the right place, same as any bullet really
4-5grns trail boss will see you right.Quote:
Originally Posted by Scott Cowan
You won't be able to use trailboss behind the 255gr subx , as it wont fit in the case behind the bullet. I tried.
What twist rate.dows.the Howa have?Quote:
Originally Posted by 338Lapua_cam
Here some of my load and results. Pic heavy to save phone typing .
I pull the 123gr fmj out of this Chinese ammo and store the powder. Then reload with HiSkor800x and put a Modded 240gr Sub-X pill in.
3 step projectile trimming process. Bench linisher 5mm off, then in lathe to trim to 1.300" , then drill to get a bigger holllow cavity and tune the weight to 240gr.
Take note that the cold & fouled bore shot is around 930fps so i have specially loaded some 10gr for cold fouled bore barrel state.
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And this shows why trailboss is not suitable for the 255gr subx pill
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My Ruger 16" barrel measures at 1in10" twist, which isnt enough to stabilise the 255gr subx pill which is 1.540" long.
This is why I trim them to 1.300" long, also it helps give decent expansion at subsonic velocity.
The lead-alloy seems too hard for subsonic use imho, if you look at the recovered bullet from the pictures above you can see decent expansion , however this is after going front on through the neck/spine and lodging against the spine on the offside behind the top of the shoulder blade.
Here is a link for a subsonic stability calculator:
https://sharpsbros.com/subsonic-bull...ty-calculator/
As has been stated, no need or use for TB in this case for heavy subs. Similar to the 300blk, even with more normal powders, there just isn't the case capacity to get such a heavy projectile going supersonic.
Interestingly, well before the .223 progenated the .300blk, the 7.62x39 progenated a subsonic round known as the 9x39. It is likely that while the 300blk is largely inspired by 7.62x39, it also derives some inspiration from the 9x39.
@Ammo Direct NZ also stock a factory 255gr subsonic load, @338Lapua_cam you can pick up a packet just up the road in Whanganui if you order online ahead of time. Might be a good way to gauge the suitability of the 255gr projectile before buying 100 to risk having 90 left over that are no good to you.
When a 151 grn goes through n through I fail to see need for 200 plus lol.
Yeah, it's a bit of an interesting question. 255gr will usually go straight through unless you hit something bloody solid - the 170gr Sub-X has a serious amount of penetrating ooomph (I shot one into a block of wood in the wife's garden and it went straight through and I still haven't found the pill after digging down over 40cm so the 255gr is more of the same!
If the lighter pills are going straight through unless they hit something as well, I'm not too sure what the gain is going for an extra 105gr except maybe recoil...
Yeah i agree, and i would love some cast ~100gr pills for subsonic possum medicine. Cause I definitely wouldnt shoot a possum with the 240gr :O_O:Quote:
Originally Posted by Micky Duck
Also Mickey you know that 'need' has little to do with why we play around with different loads and cartridges :thumbsup:
Probably the main advantage, and it is relevant in that it is hard to get TB powder right now, is that you don't need to use TB powder to get subsonic speeds. Call it a work around that doesn't compromise on pentrating ooomph.Quote:
Originally Posted by Micky Duck
There are some wicked hollow points made for the M1 carbine something like hundy grain. Years since seen them but cavity was 11 mm deep.
There is plenty of trail boss around... Folks just not parting with it lol.
Yeah we never really did. What it did do was sort of bring everything up into the light as it were, with a bit more safety than the old ways and no arcane drilling out flash holes or weirdities like that.Quote:
Originally Posted by longshot
Hornady .309 90gn XTP?Quote:
Originally Posted by Roarless20
has the 1:9.45 twist rate
a good bit of info here lads, thanks for that. but yes trail boss is not something that can be easily obtained so will be looking at alternatives.
yeah sorry about that, meant to type 255gr not 225gr...Quote:
Originally Posted by Pommy
I wouldn't risk shooting standard 255gr subx with that twist rate with a suppressor on .Quote:
Originally Posted by 338Lapua_cam
I checked the numbers for you vs that calc i linked:
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Yes, the increase in energy between the two bullets at the same is speed is only 100 or so ft lbs. Subsonics need a different mindset I think. Expansion only really occurs if bone is hit even with the flash expensive jobbies otherwise there's a leaky hole with virtually no tissue damage. Flat nosed bullets seem to perform best. There's no need for streamlined stuff subsonic. 174 gr mk V11 303 fmjs loaded backwards are pretty impressive.Quote:
Originally Posted by Micky Duck
Didn't Keith extoll the virtues of flat point bullets for cutting good wound channels using Pistol calibres and cast bullets? Back in the 30s or when ever? Translates well to rifle subsonics
Pretty definitive contemporary article right here from our very own world famous Naki-ite
https://www.ballisticstudies.com/Kno...allistics.html
The mindset thing is similar to using a bow. Got to hit animal just right,be prepared to shoot again and wait for it to bleed out if chest shot...spending more on Lehigh projectiles seems to give big increase in performance but that price tag...yeah nah not for me lol.
I've got this Green dot (500gms incl container) & Lil gun (same) if anyone's interested. I picked these up a few years ago with the same idea to do subs in my Howa x39 but never got around to it. I did use it for loading a x39 brass shell, powder, cotton wad & a piece of brass ball cock arm as a crimped projectile to use in a diving friends power head spear (apparently worked great)Quote:
Originally Posted by No.3
I'll be heading up tp the waikato in mid October if that helps.
I'll put some other powders up on Buy/sell etc soon as well as these.
Phil.
OOOPS here's the photos
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PM me if you want any.
cheers,
Phil.
I think that's why Robert's 151gr cast pills seem to perform so well. Bloody great hole in the front end which is virtually flat...Quote:
Originally Posted by Marty Henry
I've seen a few rounds made up with the .303 FMJ pill loaded backwards - for some reason very unreliable performance from them. Some tumbled and went sideways through things, some flew straight - I have no idea what the problem with them was as I've heard a lot of people put forward that they are quite good performers.
