300 blackout and 155gn Lee bullet, top speed?

[Johansson81]

The Sierra book shows 150gn at a max of 1950fps with a 16" bbl. Hornady shows 2062fps with LilGun but the rest are all under 2000fps (also 16"bbl).

Unless someone had some chamber pressure data for the lead bullet loads I would stay below those levels.

A 200gn bullet at 900fps meets the major criteria.

That sounds logical, thanks for the input.

I don't know if Major factor is calculated differently in IPSC than in other shooting sports, but in IPSC it is bullet weight x speed /1000. A 200gn bullet at 900fps is only 180PF, way short of the 320PF needed for Major.

And the trajectory from that round would make it very impractical at targets further out than 200m or so, in IPSC there are targets at 300m so I need to make the load as flat shooting as possible.

[popper]

You can come close to 320PF but never get there in BO. Definitely need a slower twist.

[Johansson81]

Another question, what lead hardness do you run in your 300blk supersonics?

I´ve been casting a fair amount of bullets for 9mm and 38spl, and found that a 50/50 mix of WW and pure lead, water dropped and powder coated is just about right. Will the same mix work for the Lee 155gn in a <2000fps gas checked 300blk load?

[John McCorkle]

Another question, what lead hardness do you run in your 300blk supersonics?

I´ve been casting a fair amount of bullets for 9mm and 38spl, and found that a 50/50 mix of WW and pure lead, water dropped and powder coated is just about right. Will the same mix work for the Lee 155gn in a <2000fps gas checked 300blk load?

I had that same set up at near 2100...I shot 2 and shot them into water jugs so I can't say what accuracy to expect...I don't imagine they were accurate to any standard. They did terrible things to the water jugs and blew the primers (too hot). Turned the bullets inside out but they stayed together. Still looking for one half of the first jug...

Sent from my moto g(7) power using Tapatalk

[popper]

This is the carbine @ 100. 145gr PB 4% Sb with a touch of Cu. PCd with NO PC on the base (testing), suspect base wasn't competely flat.

[Johansson81]

I had that same set up at near 2100...I shot 2 and shot them into water jugs so I can't say what accuracy to expect...I don't imagine they were accurate to any standard. They did terrible things to the water jugs and blew the primers (too hot). Turned the bullets inside out but they stayed together. Still looking for one half of the first jug...

Sent from my moto g(7) power using Tapatalk

Ha, that must have made quite a water spray.

Sub-2000fps seems from all the posts in the thread as the way to go with this bullet.

This is the carbine @ 100. 145gr PB 4% Sb with a touch of Cu. PCd with NO PC on the base (testing), suspect base wasn't competely flat.

So you was shooting pure lead mixed with 4% tin? No antimony? That would be like 6.2 Brinell (5+4x0.3), right?

[whisler]

Sb is antimony, not tin. So Lead, 4 % antimony + copper.

[Johansson81]

Sb is antimony, not tin. So Lead, 4 % antimony + copper.

Ah, my bad. I shouldnt have slept through chemistry class.

[whisler]

That's alright, I stayed awake for you, Lol.

[Johansson81]

That was very kind of you sir.

While being in the chitchat mode about bullet hardness, is there a recommended length of time a cast bullet should "rest" before being shot so it has time to age harden?

A couple of years ago I made a batch of 9mm bullets that didnt group well at all, keyholed and were all over the place. I put the remaining rounds away and for some reason I tried again a year later and then they grouped just fine out of the same gun. The only reason I can see it that they age hardened enough to be shootable.

(there are probably 10 forum treads about this)

[whisler]

Took my water dropped ww boolits more than a month to harden from 13 to 20 but they made it.

[Johansson81]

They got that much harder from a month of storage despite being water dropped?

I did a fair bit of internet research when I first started casting bullets but the fact that age hardening is something to take into account was nothing I came across.

[Lloyd Smale]

ive pushed the rcbs 130 to around those speeds but i think your really pushing it to do that with 155s. Might want to step up to a 762x39

[Johansson81]

Back from a morning at the 300meter range, a friend and I did some testing to figure out the trajectory of some loads.

I have made a batch of 155gn loads with 17.0gn RS36 powder under them, clocks in at little over 1700fps. They grouped just as well as the same load with jacketed bullets, size of a closed fist at 100m shot with a red dot and pretty fast shooting.

With a 20m zero I get POI->POA at 160m and I can reach out to 180m without having the POI more than 10cm from POA. 25cm drop at 200meters, and at 300m the bullet drops 95cm.

If I punched in faster velocities in a ballistic program I needed to go up to 1900fps before the trajectory became flat enough to make it worth trying, no idea how the bullet will group at those speeds but I will make a handful of loads with 17.5gn RS36 for the next range trip and find out. Not sure though if it is worth the added case wear to push them faster than 1700fps.

[Johansson81]

ive pushed the rcbs 130 to around those speeds but i think your really pushing it to do that with 155s. Might want to step up to a 762x39

The thing is that here in Sweden the upper is what needs a license, not the lower like in the States. So changing a barrel twist, caliber or length is a pretty involved process with club certificates and several months of waiting for the police to decide whether I really need another 300blk barrel or not.

So, I will make do with the one I have and find a load that suits it.

[Johansson81]

I upped the powder charge to 18.0gn RS36 and got chrono readings of aprox. 1800fps. Got a 2" group at 20m shooting standing without support which is about what I can manage with a red dot so no blame on the ammo.



When weighing the coated bullets on a digital scale I found that the 155gn bullets acrually weighs 160gn with my lead mix. With those numbers punched into the ballistics app I get a pretty decent trajectory when sighted in at 20m.

[popper]

I add Cu to the alloy for HV, thread on it here someplace (~0.5%) - helps with RPM twist problem. Arsenic ( chilled shot) will get them hard pretty quick after WD. Be sure to WD fro the PC oven! Takes about 2 weeks with As. You will get a slightly higher fps with cast over jacketed. Lilgun burns HOT. I had to pull my sizer die apart and got it set wrong so I had excessive HS and primers went flat at low loads. Even LC cases PP start to get loose with flat primers. My chamber is tight so I neck turn all brass.

[frkelly74]

Well, I had some fun with that 155 gr boolit and my 308 Win 700 Remington. I did powder coat and gas check the boolits which I sized to .311" and loaded into random brass with 13 gr of the Herco powder that I have been wanting to try. I am guessing I got about 1600 fps and all shots were on the paper. As the bore seasoned the group got tighter and I got the open sights adjusted for dead on at 25 yd. Next time I will step up the yardage out to about 100 yd. Today was kind of a proof of concept.

[cwlongshot]

Well, I had some fun with that 155 gr boolit and my 308 Win 700 Remington. I did powder coat and gas check the boolits which I sized to .311" and loaded into random brass with 13 gr of the Herco powder that I have been wanting to try. I am guessing I got about 1600 fps and all shots were on the paper. As the bore seasoned the group got tighter and I got the open sights adjusted for dead on at 25 yd. Next time I will step up the yardage out to about 100 yd. Today was kind of a proof of concept.

I recently picked up a couple Pounds of Herco. Combined with the used/open Ol' Grey metal 4# can I had.... I figured Id best start shooting it!!! Its been great in sub loads for the 350 & 450!

I did t think of trying in my bolt 300!!! Thanks for the ideas!! Ill run some thru QL and see what I get!!

CW

[frkelly74]

I do like a powder with about a century of data accumulated. I wish it metered better though.