300 blackout and 155gn Lee bullet, top speed?

[Johansson81]

Hi fellow casters!

I am building a 16" AR-15 in 300blk (1:7 twist rate) and plan to compete in IPSC with it, and I will need to push a powder coated 155gn Lee gas checked bullet to 2100fps to reach Major power factor.

Have anyone tried this mold and how fast the 155gn bullet can be pushed with good precision?

Best regards
/Anders Johansson - Sweden

[Joby]

I got to 2000 fps with 15.5 grains of Hodgdon Lil Gun. In a 1-7 twist 16” carbine gas length barrel. Had about a 3” group at 50 yards. With a low end red dot. Also no gas check. Had room to go faster but stopped.
Good luck. JS.

[John McCorkle]

I've clocked that bullet at 2150...that was an unsafe load as demonstrated by blown primers.

I will say it was surprisingly accurate out of a 1:8 twist. I did not expect to see the bullet grip the rifling like that and remain stable. Fast twist and cast typically limit your velocity window...that bullet was cast hard water dropped, powder coated and given a gas check. So it had the best chance possible for the circumstances.

I won't load them that hot in the future...prob drop it to just at 2k fps or even 1950 ish range. From what I hear that is pretty typical and expected velocity max for the bullet.

Sent from my moto g(7) power using Tapatalk

[Conditor22]

Welcome to CB Johansson81

I would recommend a slower twist rate for that light a boolit. 1:7 is for the heat subs that 300 BO is known for.

so far I've gotten my best group at 1045 fps

[Johansson81]

Thanks for your answers, I understand that I will be stretching the limits with a 2000+fps load from the 155gn bullet and 1:7 twist. Perhaps it would be wisest to settle for making an accurate practice load at 1800-1900fps from the cast bullets and buy jacketed bullets for the competition Major loads.

Unfortunately 300blk barrels are pretty rare here in Sweden and we arent allowed to own ones shorter than 16" so a Ballistic Advantage 1:7 barrel was the only one I could find. Not interested in shooting heavy subs since a silencer on a 16" barrel would be like running around with a flag pole...

I am eager to try the loads once the barrel arrives, I made my own gas check punch and will try to use beer can checks. I modified the mold a bit to make the gas check groove a bit less deep so now the 0.1mm thick gas checks has a snug fit in the case neck.

100 copper gas check would cost me like 15 dollars so I refuse to buy any.

[Conditor22]

I like "flag poles"

[44Blam]

Yeah, shoot faster rounds with J-word bullets with that setup. But cast and shoot PB boolits in a "minor" division too or for plinking... Funny thing is your 'major' division is probably dominated by 5.56 setups right?

[Johansson81]

I dont think that 223 is a caliber suited for Major power factor, to reach a PF of 320 you would need to push a 55gn bullet up to 5800fps.....

[cwlongshot]

IMHO this is a downfall of this fun lil caliber.

Super sonic LEAD Loads. The RPMs that are created make it hard to do accurately.

I have t tried it as I have better use for my super hard alloy. But that bullet cast super hard might have a better chance but it still some incredible RPMs.

If ya HAVE TO have that it might be better served with a Jword bullet. Keep the lead for more moderate speeds.

This bullet ahoots REALLY well in my bolt gun with 16g 3031 powder at about 1650 fps. Just sunday I cleared out all my left overs. Probably 15-18 rounds with 14-18g of powder all shot @ 100yards without really "trying". The group was a 1.5" ragged hole.



CW

[Johansson81]

Good point about the rpm's, I'll try to find the sweet spot where they still shoot fine and go fast enough to have a reasonably flat trajectory out to 200m or so.

I have aprox. 300kg of wheel weight lead ingots and at least as much pure lead, so my .30 casting will barely scratch the surface of the pile.

Impressive results from your bolt gun!

[MT Gianni]

If you get great accuracy you may not give up much by going minor class.

[popper]

I run my BO carbine 145gr GC PC H110 to 2150. 18" 1:10 twist with ~4% Sb heat treated. MOA. It can be done but PP don't last more than 3 reloads.

[fcvan]

I ran the Lee 155 for a bit but it became problematic when I started powder coating. Since I have a buddy who shoots an SKS that boolit works just fine. I bought an NOE mold that it a C 309-150 3R and my BO loves it. It also shoots well in my .308 rifles. I run IMR4227 in my BO loads and it cycles flawlessly with 1" groups. It doesn't get as much range time lately as I can't shoot it when I am out west and 'ugly black rifles' are frowned on in CA. All of my black and fun guns went out of state to my other house. Such is life

[Johansson81]

If you get great accuracy you may not give up much by going minor class.

My main division is Open handgun where I was going to represent the Sweden National team at World Shoot in Thailand this winter, if it wasn´t for the Corona lockdown.

Rifle shooting is more on the just for fun basis, so if I come up with a good shooting Minor load I will be more than satisfied. I just shoot the occational club rifle match so no big deal if I don´t make Major. Being able to shoot 300blk for 1/2 the cost of my 223 reloads with jacketed bullets will be awesome.

I run my BO carbine 145gr GC PC H110 to 2150. 18" 1:10 twist with ~4% Sb heat treated. MOA. It can be done but PP don't last more than 3 reloads.

I guess it wears hard on the brass, any pressure signs?

I ran the Lee 155 for a bit but it became problematic when I started powder coating. Since I have a buddy who shoots an SKS that boolit works just fine. I bought an NOE mold that it a C 309-150 3R and my BO loves it. It also shoots well in my .308 rifles. I run IMR4227 in my BO loads and it cycles flawlessly with 1" groups. It doesn't get as much range time lately as I can't shoot it when I am out west and 'ugly black rifles' are frowned on in CA. All of my black and fun guns went out of state to my other house. Such is life

It is hard to believe that the gun acceptance is much higher here in Sweden than in some US states.

What became problematic about the Lee 155gn when you powder coated it?

[fcvan]

It is hard to believe that the gun acceptance is much higher here in Sweden than in some US states.
What became problematic about the Lee 155gr when you powder coated it?[/QUOTE]

When I first shot the Lee 312-155 I used liquid alox/mineral spirits with 2 thin coats. When I started powder coating I was ESPC with a gun. I got the PC too thick which caused feeding problems. Now, I almost exclusively ASBBPC which I can give a good even coating which shouldn't cause feeding issues.I liked the profile of the NOE 309-150 3R SP and so I bought it. I split my time between California and Colorado and have casting and reloading gear at both houses. The neighbor with the SKS is in CO, so that mold is there and the NOE mold is here in CA. I will have to cast some up for an Argentinian Mauser I was gifted and that Lee mold should be just fine for killing tin cans.

[popper]

Just the primer pockets. I convert 223 and deprime separately, toss them if loose. I did do a stupid and went 2 gr over max - ballooned the case heads is all. I use the 31-142D mould PC or BLL .

[Johansson81]

When I first shot the Lee 312-155 I used liquid alox/mineral spirits with 2 thin coats. When I started powder coating I was ESPC with a gun. I got the PC too thick which caused feeding problems. Now, I almost exclusively ASBBPC which I can give a good even coating which shouldn't cause feeding issues.I liked the profile of the NOE 309-150 3R SP and so I bought it. I split my time between California and Colorado and have casting and reloading gear at both houses. The neighbor with the SKS is in CO, so that mold is there and the NOE mold is here in CA. I will have to cast some up for an Argentinian Mauser I was gifted and that Lee mold should be just fine for killing tin cans.

So you don´t size the bullets after coating? I´ve heard that using the ESPC method standing on the base without gas checks can cause leading and fouling of the compensator, have you noticed any?

Just the primer pockets. I convert 223 and deprime separately, toss them if loose. I did do a stupid and went 2 gr over max - ballooned the case heads is all. I use the 31-142D mould PC or BLL .

Aha. I use mixed stamp 223 range brass for reforming and some cases are really thick walled. I have made my own version of the WFT case trimmer with a pretty sloppy fit for the case, but some of the brass still won´t fit the trimmer so those get tossed.

[fcvan]

Johansson81

The ogive of the boolit grew too much and so even after sizing the chamber shelf would shave off a ring of PC and impede feeding. By then, I had already ordered and received the NOE mold as I had already returned to CA and left the mold in CO. The 155 with liquid alox/mineral spirits worked fine, it will work fine in the Argie Mauser, and the neighbors SKS. BTW, the 155 did the same when loaded in an AR10 .308 and an M1A in 308. Pretty much sold me on the NOE mold. Also, I did not notice any leading issues in the gas tubes or the muzzle devices of the 300 BO, M1A or AR10.

[charlie b]

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.

[gpidaho]

My best 300 Blackout load so far is a powder coated 129gr. Noe gas checked over 17gr. LilGun sized .309. Now that I have a load that functions well I need to chrono them to see what the fps is. Gp