300 blackout with C312-155-2R

[turmech]

I have Been working on some loads for my AR in 300 blackout with the Lee 312-155.. I am pushing it accurately to around 1950 fps with H110. I guess my only concern is that pointed nose bullet. I would be more comfortable with a flat nose design. Being lucky enough to have several rifles to choose from for the upcoming season and my mind drifting already to the upcoming fall I am curious as to what the forum has to say.

I was wondering if anyone had used this combination with success on whitetails?
Has anyone found a flat nose one that is working well in an AR platform?

[Jupiter7]

I shoot Noe clone of ranch dog 311-165 170gr RNFP out of my 10" 300blk pistol. With 14grs Lil Gun seated 2.0", LLA tumbled and alum. gas check, i get 1700+fps. Gains about 100+fps out of 16" rem 700 sps. In the pistol with 1-4x scope, freehand cloverleaf at 50yds. Range scrap/WW mixed alloy(probably 70/30, mostly range scrap) water quenched. Should be good medicine to 100yds.

I'll also be trying the accurate 31-240e(drops 245grs) from straight range scrap, air cooled over 10.2grs lil gun, runs 1245fps in AR pistol. Still need to do expansion testing. But it feeds as fast as I can pull the trigger.

[turmech]

I shoot Noe clone of ranch dog 311-165 170gr RNFP out of my 10" 300blk pistol. With 14grs Lil Gun seated 2.0", LLA tumbled and alum. gas check, i get 1700+fps. Gains about 100+fps out of 16" rem 700 sps. In the pistol with 1-4x scope, freehand cloverleaf at 50yds. Range scrap/WW mixed alloy(probably 70/30, mostly range scrap) water quenched. Should be good medicine to 100yds.

I'll also be trying the accurate 31-240e(drops 245grs) from straight range scrap, air cooled over 10.2grs lil gun, runs 1245fps in AR pistol. Still need to do expansion testing. But it feeds as fast as I can pull the trigger.
I have that mold and was actually thinking it may work. Is that crimped in the top lube groove?

[Jupiter7]

Not crimped into a lube grove. Top lube groove and crimp groove are completely out of case. Lightly crimped at top of 2nd drive band. This is where feeding worked best. Also keeps top of gas check in the neck. I started at 1.91", cartridges would move forward in mag after about 3 shots, would cause a 3 point jam into top of chamber. Have to drop mag and work charging handle and let it fall from empty mag well, not pretty.

Side note, I thought about drilling a few lee 312-155's about 1/3" with a very small bit and maybe using a counter sink to increase cup diameter a little. Haven't tried it yet.

[turmech]

That is helpful information. I was thinking of having accurate molds make a custom mold. Sounds like minimum OAL may be somewhere around 2.0 for feeding by reading into your post. That is also similar to what my OAL was for the Lee mold I was using.

[dk17hmr]

To pointy as is. You could drill a little hole in it or file a flat on the nose.

[Outpost75]

Check out the group buy on the original Ed Harris design, which was a FLAT nose!

Seems that Lee made theirs pointy to look more like Ball ammo for the uneducated masses, but that was not what the original design was. Check out the drawing in the Active Group Buy section.

[2wheelDuke]

Check out the group buy on the original Ed Harris design, which was a FLAT nose!

Seems that Lee made theirs pointy to look more like Ball ammo for the uneducated masses, but that was not what the original design was. Check out the drawing in the Active Group Buy section.


You beat me to it. I've got my name in the hat for one of the original CE Harris design.

I used one of the Lee 312-155's ( a few actually ) with poor results on a sow earlier this year. I think my alloy was too hard, because they just penciled right thru her like FMJ ammo. A guy was using a Saiga in 7.62x39 with ball ammo with similar results.

On the other hand, another guy was using Sierra 125gr Pro Hunters in his .300blk that knocked them for a loop.

[Jupiter7]

I opted out on the hm2 312-155 Harris design. Very similar to the noe 155 that has reportedly not fed well in AR15's for some. Eventually, we'll all get together on a 300Blk specific bullet for autoloaders that's a good plinking and hunting bullet.

[popper]

I had trouble with FN in AR10 till I reworked the metal mag lips. 2 nd moves forward a bit but the case tilts nose up and will fire a 20 end mag without fail. I do have to watch the head for extractor damage that will pull the case forward.

[turmech]

I tried some of the NOE ranch dog clones seated to 2.0 OAL and could not get them to feed in my gun. Really not even close. Tried 4 different mags was a no go for me. I am beginning to think my AR will need a pointed bullet at least by what I observed trying to feed these flat nose bullets.

[Jupiter7]

I tried some of the NOE ranch dog clones seated to 2.0 OAL and could not get them to feed in my gun. Really not even close. Tried 4 different mags was a no go for me. I am beginning to think my AR will need a pointed bullet at least by what I observed trying to feed these flat nose bullets.

What mags? I should have added, the flat points only feed for me with newer designed anti-tilt followers. D&h, magpul and lancer have all worked. C-products with orange or yellow followers didn't , neither did the AR stoner 10rd mag. Same held true for the accurate 31-240e.

[turmech]

I tried the 4 brands I have which were C products, tapco, thermo mold and magpul. The magpul did feed the first round in to the chamber when I cycled the charge handle. The second round jammed as bad as the other magazines. To me it did not even look close to working. The nose of the bullet were impacting the feed ramp leading into the barrel (guess that would be what it is called) I am fairly new to the platform and never was a black gun guy so I am by no means an expert.

[x101airborne]

You can take your barrel off and modify the feed ramps a little or order a different barrel bushing to accommodate the fatter nose. I had to change barrel bushings on my 7.62x39. Look at how Remington modified the feed ramps on their barrel bushings for an idea.

[DanWalker]

You can take your barrel off and modify the feed ramps a little or order a different barrel bushing to accommodate the fatter nose. I had to change barrel bushings on my 7.62x39. Look at how Remington modified the feed ramps on their barrel bushings for an idea.
I have an AR47(7.62x39AR) too. What barrel bushing do I need?

[Smoke4320]

I got in on the Milhec 312-159 HP and FP ..
just shot 25 last night
16.5 grns RL 7
OAL 1.850
Pc'ed HF red
no feeding issues at all in a Noveksi 10.5" AR
1/2 to 3/4" repeatable groups at 50 Yds .. went to he!!!!! at 100 yds
looks like its going to be some development time .. but I had ZERO feeding issues

[DanWalker]

GREAT to hear! I got the same mold waiting for me at home!

[turmech]

Would you happen to have any links to the Milhec group buy or a pic. I tried looking through the group buy section and did not find it. I am thinking of having Tom at accurate mold make a custom mold for me. It would be nice to get an idea of designs which have work. Thanks, Bill

Edit: I think I found the thread for the milhec bullet.