Lee 312-155 and the 300 BO AR upper

[sixgunner452]

I made a few dummy rounds with my available 30 cal bullets. Most would not chamber, catching up on chamber, played with seating depth. I was able to chamber 1 test cartridge, Cycled by hand. Case ejected by hand a little hard. Case ejected, bullet did not. Lodged in the barrel, sized to 312. Pulled out the cleaning rod, dis-lodged.

My available 30 cal bullet's appear to be too short in length to chamber reliably. Maybe do-able, if sized smaller. Assembled rounds still kinda short to my taste.

I already ordered a 309'' sizer die a few days ago, anticipating this problem.

Today, I decided I would also order a more "suitable to the 300 BO" mold as well. The Lee 312-155 mold is in route.

Any forum members using this "made for AK 7.62" bullet in the 300 BO?

Any and all advise welcomed. Thanks, Randy.

[johnsonian09]

Are you trying to work up a super or subsonic load?

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[Jniedbalski]

They need to be sized to .311 or .310 to chamber . My savages bolt guns like .311 but some might like .310 or .309

[6.5 mike]

I have used the 160 gr with good results in a few rifles. 30 herret 10 in bbl, 325b 30-30, 308, 30-06,& 300 blk. My ar upper likes it with a 1 in 8 twist, either sub or super. I do have a ruger bolt in 300, but am still breaking in the bbl. My mold drops at 0.3105, so I can work up or down as I need. Oops, forgot the 7.62x39 ruger bolt. Very easy boolit to paper patch if needed.

[sixgunner452]

I am trying to work up a load that will cycle a 10.5'', pistol-gas-system, 1-8 twist AR. Nothing screaming. I believe 1700-1800 ish will get it (lower would not hurt my feelings). I am saving my pennies for a 200 plus gr mold for the subs.

The molds I currently have are not suitable for this purpose I believe. I have a RD 165 (big-fat meplat) I was really hoping would work. Useless sized to 312. Kinda short for a 175-ish grain bullet. Might chamber at 309'', or 310''. I ordered a 309 sizer. Figured I could hone it to 310 if I needed to.

I don't have alot of experience loading for AR's. It's a learning process.

I figured why re-invent the wheel. I have been the recipient of much knowledge in this forum. Love the place.

I did ponie-up, and order a Lee 155-312 mold too, thinking it should be up to the task. Waiting on the mold and 309'' sizer. Kinda stuck now, waiting. Just doing my home work.

Many thanks, Randy.

[sixgunner452]

6.5 mike, thanks for the info on the 160 Lee. I opted for the 155 Lee because it appears to have a (pointier?) nose. Figured would chamber easier in an AR anyway. My hunting style bullet so far are, no Bueno. Randy.

[John McCorkle]

I am trying to work up a load that will cycle a 10.5'', pistol-gas-system, 1-8 twist AR. Nothing screaming. I believe 1700-1800 ish will get it (lower would not hurt my feelings). I am saving my pennies for a 200 plus gr mold for the subs.

The molds I currently have are not suitable for this purpose I believe. I have a RD 165 (big-fat meplat) I was really hoping would work. Useless sized to 312. Kinda short for a 175-ish grain bullet. Might chamber at 309'', or 310''. I ordered a 309 sizer. Figured I could hone it to 310 if I needed to.

I don't have alot of experience loading for AR's. It's a learning process.

I figured why re-invent the wheel. I have been the recipient of much knowledge in this forum. Love the place.

I did ponie-up, and order a Lee 155-312 mold too, thinking it should be up to the task. Waiting on the mold and 309'' sizer. Kinda stuck now, waiting. Just doing my home work.

Many thanks, Randy.That Lee mold has alot of success for several folks. 1800 is fairly easy to get.

It will load, cycle and feed fine. Will need sizing...I powder coat and gas check mine. Does great

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[sixgunner452]

John McCorkle, I currently do not PC. Have a bowl and the PC powder to start. Just need an oven. Haven't found a need so far. Think this may be the reason I need to start.

Currently, I just use LLA, and or a gas check. In the past I have pushed LLA to 1800 fps, minimal leading. I have a couple molds I've had cut PB and GC. For most of my needs PB and LLA works.

I've seen a few Utube vids guys are PCing this bullet, running pretty fast without GC. Kinda like to get away from the gas checks. PC may be the answer. Thanks, Randy.

[johnsonian09]

Sixgunner, do you want to try some powdercoated taco boolits? They are 225grn

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[sixgunner452]

Johnsonian. I sent u a pm. Randy

[imashooter2]

They need to be sized to .311 or .310 to chamber . My savages bolt guns like .311 but some might like .310 or .309

This. .312 expands the neck on my brass too much and they wedge. .310 runs flawlessly.

[sixgunner452]

imashooter2, I am hoping this is my problem. Waiting for a 309'' sizer as we speak. Thanks, Randy.

[imashooter2]

I load the Lee C312-155-2R sized .310 and conventionally lubed with White Label Carnauba Red. Speer says 17.0 grains of RL7 will push a 165 grain jacketed bullet at 1,600 foot per second and my Lee boolits weigh in at 157 grains lubed and checked. My bore slugs at .3075 and there are no issues with leading.

In preparing for the cast boolit journey I sought a lot of advice, pretty much as you are. It seems the vast majority of AR cast shooters powder coat. It does seem to have advantages. Cleaner, perhaps able to do away with checks particularly on subs… but it also looked slow and messy on the videos I watched. Add in the whole new pile of containers and racks on top of my existing pile of containers and racks and I decided I was going to stay with conventional lube unless I found a serious down side. That never materialized, so I’m sticking with conventional lube.

So keeping my prejudices in mind, you might want to more carefully examine the nose diameter of your castings compared to your bore. You stated that when you cleared your jam and got the case out, the boolit stayed. If this boolit is already engraving rifling, powder coat will make it worse.

[sixgunner452]

imashooter2, Thanks for the insight. Randy.

[sixgunner452]

Gentlemen, I finally made it out to the range to try a few loads. I fired a total of 60 loads. The loads were all with the Lee 312'/.155 boolit, sized 311'' LLA lubed. The cases were half, once fired 300 BO cases. The other half were converted 5.56 range brass. I did not check for accuracy, just function.

All of my loads cycled the bolt and locked it back after last shot. I did however have 3 cases that failed to fully chamber. These 3 cases were my converted 5.56 brass (2 of the 3 were same make). All of the factory 300 BO cases fully chambered. All loads were ignited by Winchester pistol primers, cause that's all I had. Reloading components are getting hard, and expensive to find. No leading of the bore to speak of.

2400 GRAINS RESULTS
12.0 LD AND EJECT - 3-4 O-CLOCK/ BOLT LOCK BK
12.5 LD AND EJECT - 3-4 O-CLOCK/ BOLT LOCK BK
13.0 LD AND EJECT - 3-4 O-CLOCK/ BOLT LOCK BK
13.5 LD AND EJECT - 3-4 O-CLOCK/ BOLT LOCK BK
14.0 LD AND EJECT - 3-4 O-CLOCK/ BOLT LOCK BK / SLIGHTLY FLAT PRIM (Just beginning to flatten)
14.5 LD AND EJECT - 3-4 O-CLOCK/ BOLT LOCK BK / SLIGHTLY FLAT PRIM (Just beginning to flatten)


VECTAN BA 6 ½ GRAINS RESULTS - Note: BA 6 1/2 burns dirty (residue). Hope it will clean up with slightly hotter load
12.0 LD AND EJ /5 FT - 3-4 O-CLOCK / BOLT LOCK BK
12.5 LD AND EJ / - 3-4 O-CLOCK / BOLT LOCK BK
13.0 LD & EJ GD / 3-O CLOCK / B. LOCK / SLIGHTLY FT PRIMER (Just beginning to flatten)
13.5 LD & EJ GD / 3-O CLOCK / B. LOCK / SLIGHTLY FT PRIMER (Just beginning to flatten)

The 3 cases that failed to chamber were saved, after removal from my tied up action. All 3 had bright rub marks around the necks, by the bullet crimp. I need to determine if the converted cases are the culprit, or too fat (311'') boollits.
291302
291303

I did buy some PC, plan on trying theses PC coated boolits at 309''. I also bought a Lee 230 grain mold to try. Thanks, Randy.

[sixgunner452]

I haven't bought any powder in a couple of years. Last purchased locally (20 miles, 1 way). I blindly drove to same shop yesterday. Shelves completely bare. Zero powder or primers.

So, I place an order for some 296, 1680, and 4227 powder. Couldn't believe I found any. Most I've ever spent on gunpowder.

So, many experiments in the future. Randy.

[imashooter2]

I’ve seen AA1680 and IMR4227 around (bought an 8 pounder of 4227 for the BLK myself) but haven’t seen W296 or H110 for some time.

Congratulations on your success! Keep us updated as the project continues.

[sixgunner452]

imashooter2, Brownells claim they have it in stock. My order is processing/waiting to ship. Randy.

[popper]

Converted brass often needs neck turning as the wall is thicker than the neck of the 223. I try for 10 thous neck thickness for my BOs.

[sixgunner452]

popper, I plan on checking the 3 rds that failed to fully chamber. I have a feeling mine are alot larger than factory brass. Thanks, for your guidance, Randy.

[bruce drake]

Odds are its the converted brass if the majority of your reloads functioned at those bullet diameters and seating depths. It makes a for a fun and easy load for 1-8" twist 300BLK rifles once you get the kinks ironed out.

[sixgunner452]

bruce drake, I believe you are correct. I will do some measurements tomorrow. I also have a 1 in 8'' 300 BO. But, mine is a 10.5" pistol barrel. Randy.

[WinchesterM1]

I’ve got some NOE molds, if you would like to try some out before you get a mold, I’ve got a 310-130SP and a 225 round nose

[sixgunner452]

WinchesterM1, Thanks for the gracious offer. I PMed you.

[sixgunner452]

Gentlemen, I did some measurements today. The board members guessed correctly. My cases outside daimeter at the neck are large. Here are the measurement.....

300 BO case measurement result's

Factory G&L 300 BO cases - resized - before loading
.325” to .326” outside diameter

Unfired loaded cases that would not fully chamber
G&L Coverted cases / #1 – outside dia .335” / #2 – outside dia .337” indside AVG – 10 to .11 thou

So. If I understand correctly. Some of my converted cases OD is too large. The inside Diameter seem 2 be OK>

Toss, or turn necks of offending cases. Thanks, Randy

[sixgunner452]

Brownell's sent update. Powder has shipped, has track number.