2400 in 223

[jackmanuk]

first outting

http://www.youtube.com/watch?v=eUvzr...ature=youtu.be

i shot about 70 rounds today of home loads with around 9.3 grains of 2400 , the rounds were not hot and no stress signs , so i rekon i will have to try 10 , 10.5 , 11 grains maybe even 12 and see whats what

[AlaskanGuy]

Before folks assume that actual flakes of powder are escaping before the bullet, consider this...

we do NOT know how many takes it took before they got a video that really showed what they wanted to show, If I was gunna assume anything, I would assume that the tiny flakes were left in the bore from the shot prior, not they escaped as the bullet was fired.... The gasses that escaped were prolly already in the barrel is what I am thinking..... but we do not now how many times the gun was fired before they got what they wanted for the video...

AG

[David2011]

I have read this several times and I can't come to the same conclusion. It makes little sense to me.

The jacketed bullets (most jacketed bullets) are solid from base to ogive. The Lead bullets are not solid as they (most lead bullets) have lube grooves reducing the amount of actual bearing surface.

The old Barnes solid copper bullets generated high pressures in weak to moderate jacketed loads. To solve the problem they introduced "rings" or "grooves" into the bullet reducing bearing surface thus reducing pressure. Very similar to the lube rings in Cast bullets, especially Tumble lube cast bullets.

I have to think that the lube grooves in cast bullet reduces bearing surface, not increase it.

Steve,

I would have to agree with the statement you quoted for this response when related to rifle bullets only. Generalizing, most jacketed rifle bullets have fairly short bearing surfaces. Most cast rifle boolits have extended bearing surfaces. This is obviously a complex subject but I would have to agree that in general, cast rifle boolits have more contact with the barrel than jacketed.

I have been of the assumption for years that lead had better lubricity than copper but now wonder about that.

The video is interesting. I have no queston that gas is bypassing the bullet which appears to be a jacket soft hollow point in .45 ACP. Played in stop frame, a ring where the jacket meets the soft point is visible just as the bullet reaches the right edge of the frame. The unburned flakes of powder appear to be from the previous shot and propelled by the blowby. The muzzle indicates that at least one previous shot had been fired since it was cleaned.

Got to wonder if cast produces higher pressure because of the requirement to be swaged into a bore smaller than the OD of the boolit to prevent leading or if it's a lubricity difference. Seat of the pants says the swaging is not insignificant in the overall pressure. It would be interesting to see an oscilloscope trace or other time vs. pressure data of the pressure transitions for cast vs. jacketed.

Off topic: Also interesting is that the gun is still fully locked in battery when the boolit leaves the barrel-something I've assumed but never seen before.

David

[jackmanuk]

i always assumed it stayed locked otherwise you accuracy would drop , i like how i started a massive debate over an assumption . i jsut watched the vid and IMO that they are not power flakes before the bullet but residue from the previous bullet as one of last and larger chucks to fly out look more like a flat irregular peice of lead rather than a power grain



let the long winded replies continue

[Old Caster]

I wonder if doing something like putting magic marker on a jacketed bullet and then seeing if it was smeared off everywhere after being fired would make this more clear.

[GabbyM]

I may not be perceiving the debate properly.
What I'm thinking about this ejected material is. Bores have residue in them with some loads. When a bullets is pushed down the bore it's is a piston in a bore. Air and material will be pushed out in front of it at high velocity. Is my thought process in error?

[nicholst55]

IIRC, the Lyman 47th Edition reloading book has a section for T/C Contender data. In there, they list data for 2400 (and jacketed bullets) in the .223 Rem. I tried some of their loads in a Remington 700, and it worked just fine. The recoil was almost nonexistent, and accuracy was acceptable. It's been many, many years since I tried this, so the details are a bit fuzzy. As I recall, velocity in a 14" Contender barrel wasn't far behind a 20" AR-15 barrel with comparable bullets. It was curiosity that made me try it, and curiosity satisfied, I moved on.

[GabbyM]

first outting

http://www.youtube.com/watch?v=eUvzr...ature=youtu.be

i shot about 70 rounds today of home loads with around 9.3 grains of 2400 , the rounds were not hot and no stress signs , so i rekon i will have to try 10 , 10.5 , 11 grains maybe even 12 and see whats what

Very nice video there jackmanuk:
I don’t run cast in my AR’s because I have bolt gun 223’s for that. But your video shows nicely how slick an AR runs on a straight pull bolt when magazine feed. All the parts are over the counter thanks to the HP rifle shooters running them in longer than magazine length heavy bullets.

One of the things I don't like about AR's is the dented brass. A straight pull setup would solve that and still be far faster than a turn bolt. I'll stick with my bolt guns sporting pretty wood however. May hang onto my red pajamas too. With teddy bears.

[GabbyM]

Actually when I do run cast through either of my AR rifles. My brass does not dent as it is softly ejected.
Then my old SP-1 Colt does not dent brass. It took the US Government to design a rifle that screwed up Stoners design.

[SlippShodd]

When I was trying to get cast going in my AR last year (55 gr mould dropping a 62ish grain boolit w/check) I think I got to 17 or 18 grains of 2400 before I gave up on it and switched to better powders. My issue was that I couldn't get the gas system to operate. Took 22 grains of 748 (as a comparison) to do that reliably. The accuracy with those 2400 grain loads was outstanding, just wouldn't run the gun.

mike

[Moonie]

I've found a strip of stick on velcro/hook & loop on the deflector fixes the issue with dinged up brass, even with full power jacketed loads.

[osteodoc08]

We can also look at the 45 acp. Very popular with lead bullets, yes.

Lost of powders to choose from, I'll pick from Hodgdon data for this one.

W 231 Jacketed Max = 5.3gr @ 16,800CUP
W 231 Lead RN Max = 5.3gr @ 16,900 CUP

My Favorite 45 Powder, WST.

WST 230gr Jacketed = 4.9gr @ 16,100 CUP
WST 230gr Lead RN = 4.3gr @ 16,400 CUP

Still the same, lead bullet achieve higher pressure with less powder. According to this Pressure data, he is correct.

How did they arrive at the pressures? A test barrel? A calculation?

[runfiverun]

with a transducer.
the lead simply obdurates the barrel better [jeez I hope I don't start the obturate/obdurate thing again]
it seals the gasses of from the start rising pressure right off.
lead has a lower engraving pressure than copper.

[swheeler]

with a transducer.
the lead simply obdurates the barrel better [jeez I hope I don't start the obturate/obdurate thing again]
it seals the gasses of from the start rising pressure right off.
lead has a lower engraving pressure than copper.

Yep you started it again, I think you mean obturate.

[Pinsnscrews]

Silhouette loads tend to be loads that have enough power behind the bullet to knock the steel plates down without actually damaging them. Most of the loads I am working up for my T/C are soft point or flat point rounds. In my case, my local range also has a cap on velocity. So in theory, I want heavy for caliber loads on my fast cartridges, without extra length, so a round point/soft point bullet will still be accurate with the extra weight and shorter overall length to work with slower twist rates.

[runfiverun]

FACE/PALM.....

[MGySgt]

I have shot 2400 in an AR and had excellent accuracy at 100 yards with the Hornady 55gr FMJ-BT. It would eject, but the bolt didn't go back far enough to pick up another round.

As your AR doesn't have a gas system I don't see that as a problem.

I think I stopped at about 14 grains as the primers were being flattened pretty good and the cases were real hot. Not much of a pressure check, but I didn't go any higher.

According to Quick Load the max should be about 15 grains with an OAL of 2.260.

Good luck with your 2400 loads.

[walltube]

jackmanuk,

Not wanting to be a scold here; to "assume" anything when searching for and developing a satisfactory load for a given firearm is courting disaster. I see in your post no.3: "assume". Please, no assumptions.

There, you have my short winded contribution.

Regards,
Wt.

[jackmanuk]

thanks for the info , the 9.5 grains was a nice soft easy load so im trying 10 and 11 .... but i dont think il try 15