Have you looked into the Mihec group buy mould on castboolits.gunloads.com? We're trying to get a 230gr with a Cramer HP made. It should chamber much better than the 247gr NOE.

I have been begging noe to make some of their 230gr blackout moulds. They also have a much smaller meplat and should work much better in an AR platform. It's basically a remake of the Lee 230gr mould but without the boat tail.

Thanks for the heads up. Looks promising.

Self quote for context.

This is the best I could get out of the loads mentioned above (50 yards).  It was a bit windy today. They run great in the rifle but are not grouping as well as I would like. Chrono data in image.

Yes I have considered and will be doing that soon. I don't think it will improve accuracy much but I do like the coated bullets (not as messy, less smoke). I have shot MBC coated bullets but have had leading problems from bases melting while trying to get what I call "Max Sub" (1050 fps) with a 245 gr bullet out of an 8" barrel. Wish I could get the MBC's powder coated with a gas check. Anyway that is what I will put together soon. I will use the NOE 247, powder coat, then size and gas check. Will be a while before I can get everything together.

I was thinking the coating would not adhere properly after sizing so my plan was to light coat, size and gas check the follow up with another coat. Does that sound reasonable? I do know the NOE is already tight with gas checks which I like because I am running these through a suppressor.

I have been using Lee sizers to I size all my 30 Cal., among others, I have one for 308, 309, 310,and 311 I believe I may even have a 312.

Generally I pan lube then size. Sometime I use Alox but not often. It works fine. I just don't like the way bullets can pick up dirt etc.

By the way, almost looks like part of my bench. I use the rockchuker to size and load on the 550b.

Do gas checks make subs more accurate?  I read they are not necessarily needed for powercoated subs.

What kind of tinkering was required? I have a 10.2 inch suppressed SBR.

Not an accuracy issue.

Out of an 8" barrel I have to run gas checks to get a 225-247 gr bullet up to 1050 fps. If I don't the base of the bullet melts and causes leading in the gas system.

I get deposits in the gas key and on the bolt tail and in real bad cases around the gas rings. Lead also builds up on the muzzle and in the blast chamber of the suppressor.

The powder coating on the MBC 245 gr. bullets was not enough to overcome the problem. Probably ok out of longer barrel.

To get 1,050 fps out of an 8" barrel with that heavy of a bullet drives pressures up to what I am guesstimating to be 34,000 psi or more.

The melting as I understand it is a time/pressure thing. Apparently the base is exposed to high pressure long enough to melt.

Gas checks solved the problem.

I found that groupbuy. That mold would feed well in an AR15?

I guess the gas checked is the way i need to go with my short barrel.

I know (well... assume) it will in mine. My feed ramp has been opened up to allow for wider meplat bullets. This mold is narrower than what I am running already.

As far as the gas check goes I don't want to say you have to have it. I just know that I have tried enough without to have decided I won't run without.

If you run a can make sure the gas check is very firmly attached to the base of the bullet. I have never had one come off and damage a can or chrono. But I guess it could. I don't worry about it...anymore.

Pardon my ignorance but besides sizing, what is going on in this pic? Looks like you're putting a copper base on the cast bullets?  I've yet to see nor studied the process as I havent considered casting until recently. Thanks.

Those are the gas checks, copper disc goes on the base of the bullet to stop the powder charge from liquefying vaporizing the base of the cast bullet.
 

Thank you. That makes a lot of sense. Made me have a duh moment as I was under the impression the the "ribs" around the base of the bullet were gas checks.

The intro mould is the Lee 309-230-5R. It is 230 grains, feeds great, but does not have the best reputation because they were stupid and put a boat tail on a stinkin subsonic round (for some reason). Amazon Link

NOE has a 230gr mould that is similar to the Lee 309-230-5R, but does not have the stupid boat tail on it. I would wait until they "eventually" have those in stock. It has a smaller meplat and will load better in the AR platform IMHO.


I have been pestering the crap out of them to make them with the PB (I prefer PB for subsonic velocities). I am powder coating and really don't think gas checks are necessary for powder coated subsonic rounds assuming the right alloy is used and the boolit is sized properly.

If you do want the gas check version there is one 2 cavity brass left in stock 2 Cavity Brass Mould and three 4 cavity aluminum in stock 4 Cavity Al Mould.

There is also a 4 cavity aluminum that has 2 cavity gas check and 2 cavity plain base: Link to 2GC 2PB 4 Cavity Aluminum Mould


You can also put your name in on this group buy and maybe in a few years you will have a gorgeous Mihec work of art. Its a 230gr Cramer HP mould: Link to group buy

The NOE 245 is not the only bullet out there in fact NOE has another mold for Blkout that I may get soon.

As far as gas checks go, I wish Drfroglegs could figure out how to get a 220-245 gr bullet to not melt without gas checks out of an 8" barrel at 1050 fps (max sub).

I have been trying for a good while with no success.

Gas checks have been the only solution so far.

If he can figure it out it will save me some time and an extra step in my bullet making process.

Understand I am not saying he is wrong I just have not achieved that with an 8" barrel going "max sub" fast.

Here is a fired NOE 226 gr with gas check still in place. The bullet (1,000 fps) fractured at the hollow point and mushroomed when it hit bottom of a full barrel of water.

I have had good luck with Lil' Gun, IMR 4227 and A1680. I find that A1680 was most accurate but also the dirtiest.

Right now I am working up some 4227 loads. 9.7 gr for the 226gr bullet (8" Barrel).

I am using a 123 gr PC bullet at about 1500 fps and I get the same leading in the gas system. Profile won't allow for GC.

If it is coming back through the gas system, then I am also breathing it in.

Looks like I am going to have to keep looking.

You have to hold your breath.

That is taking the natural respiratory pause a bit far. If only someone sold a 120-150 gr PC GC bullet.

I wonder if the 200 gr range has the same vaporization problem? I have a box of 245 MBC I haven't opened, looks like I will probably trade them off.

Have you been shooting powder coated or polymer coated? I've never had a trace of lead in my barrel. I've shot mainly the Lee 309-230-5R and even shot the MBC 245gr coated boolit (which is a PB design).

Leading is caused from gas going past the bullet and "eroding" the edges of the bullet. If you have a properly sized boolit that obutrates properly you should never have leading. That is not always the case, which is the whole reason coated boolits have hit it so big.

There is no reason you should ever have leading from a coated boolit, regardless of the design, at subsonic velocities IMHO. There is no exposed lead, how can you?

For anyone that still questions how to determine cartridge length for feeding from an AR magazine, here is how I do it using a Hornady bullet comparator with a .25 caliber insert.
I put a couple empty cases in the mag to make measuring easier, then measure from the base of the case to the rib in the mag. Caliper is on the base of the first case inserted in the mag (make sure it is completely to the rear of the mag). A second case was inserted to expose the rib for easy measuring.

I then use the 1/4" hole in the comparator to measure the bullet seating depth, placing the face of the insert where the rib is in the mag.

Easy, and a perfect fit every time. This example is a 150 gr Hornady spire point.


 
 

 

Cant see images

Well explained.  The comparator method is great.

Reloading .300 Blackout for the first time and have run into an issue concerning COL. I am loading Hornady 150gr. FMJ-BT (I have lots of them)in front of 13.5 grains of Win 296 using CCI#400 primers and once fired PNW Arms brass. Hornady's COL for this bullet powder combo is 2.220"; this has the bottom of the cannelure about 0.170" above the case mouth. This does not seem correct; has anyone else had experience with this load data? I have seen some talk searching the web that it should be b/t 2.065" and 2.080".

Self quote....

I FINALLY got back out today and did some UN-reloading

Barnes 110gr.  2325 fps ES 21 SD 9 (factory loads)

Remington 220 gr Subs...well its Remington 1021fps, ES 119, SD 28

MBC 245 gr / A1680
@ 11.5 1141fps
@ 11.3 1125fps
@ 11.0 1121fps

The slower the better for group size, so time to work lower.

Wasn't as much lead smoke, so that's good.

I was not expecting the POI change between the supers and the subs (ok un-subs) to be as much as it was. With the barnes I was shooting over top of the target @ 50 yds.

Still 100% feed and function with the MBC 245gr.

ETA

Just loaded 5 each at 10.7, 10.5, and 10.3.

I will see how that shoots. May pop out into the yard and send a 10.3 through and see what kinda speed that gets me.

Anyone know how little a charge I can get away with?

ETA

10.7 = 1061 fps
10.5 = 1016 fps
10.3 = 1004 fps

That was only 1 shoot each

Looks like 10.6 is worth a looking at

That was my thinking as well. But in the bullets that were coated (MBC 245 coated) the boolit base burned and lead melted (I never had leading of the barrel. Just leading on bolt tail, gas key, muzzle and blast chamber of suppressor). I do not think the polymer coating is enough to protect the base from the 34,000 psi and the duration the bullet is exposed to those pressures. I am only hypothesizing on what is going on. I can only definitively say that going to gas checks solved the problem. I just received some .310 sized MBC coated bullets to test (custom order). I will be loading some in the next few days and hope to have results.

If I recall what I've read of home-powder coating bullets, it takes some effort to make sure you get a consistent coating on the bullet base.  I wonder if this is what's going on with melted bullet bases...

The MBC 245gr I got look very even as far as coating.

Also with the lighter loads , Im not seeing the smoke.

My weekend project is 10.6 gr and see how that goes.

Im really liking these bullets and the .300 Blk in general. I decribed it today to a co-worker as a cross between a AR15 and a Red Rider with 245gr BB's

In my case I am using bullets coated by MBC (very evenly coated). I am trying to figure out the correlation of pressure to barrel time. I am not sure but I think high pressure (34,000 psi) + long relative barrel time (1,050 fps) is causing the problem. I could be way off base but hopefully will get this figured out. I sure would like to run plain base cast boolits if possible.

From what I understand the melting is a combination of time and pressure. With a 16" barrel and a 245 gr bullet, to get 1,050 fps the pressures are 18,109 psi. To get the same velocity out of an 8" barrel will give pressure of 36,219 psi. With a 12" barrel the pressure is 24,164 psi. (rough calculations using Close Focus Research "Calculating Barrel Pressure and Projectile Velocity in Gun Systems" spread sheet).

To be clear, the spreadsheet does not have a 300 blackout calculator but does have a 308 calculator that I used. The bore size is the same and calculations are based on bore size, barrel length, bullet weight, and bullet velocity so the data should be somewhat similar. Chamber size, powder choice and burn rate do not enter into the equation.

Using another portion of the calculator and changing from 62,000 to 55,000psi (SAAMI pressures for 308 and 300 blk) it shows that at 55,000 psi a 245 gr bullet out of an 8" barrel will be going 1,294 fps with a muzzle energy of 911 ft-lbs. So I guess don't push your heavy bullets faster than that. (THIS IS JUST CONJECTURE! DO NOT USE THIS INFORMATION TO DETERMINE LOADS!)

What confuses me is that SAAMI Data for 300 BLK (16" barrel) shows that a 220 gr bullet going 1,020 fps has pressures of 55,000 psi. That does not make sense to me considering some seem to have problems cycling subs due to lower pressures and I suspect they (SAAMI) are just showing a subsonic load.


ETA: I found a reference to using gas checks in ported guns to eliminate cutting as the base of the bullet passed the port. As the bullet passes the gas port gasses escape past the base and cut the bullet. This sounds exactly like what is happening with PB bullets in the 300BLK out of an AR platform. Read the paragraph right next to the 454 casull image. From Ingot to Target

ETA 2: Looked at the gas check of a fired 225 gr bullet and noticed an uneven burn on the gas check. I wonder if this is from gas rushing past as it passes the gas port?

Anyone have good reliable load data for hornady 208 gr amax for subsonic?

Will be using a 10,2 barrel and suppressor. I have shot the factory rounds from hornady and they seem to work the best out of my gun.

Thanks.

I will rustle up some load data sometime tomorrow.

In the meantime A1680, IMR 4227, Lil' Gun, H110, 296 are all used in 300 BLK among others. I personally like A1680 for accuracy and IMR 4227 for cleanliness. I run both out of an 8" suppressed.

Off the top of my head I think it's 10.7 Gn of 1680 with a COL 2.120.

Will be using a1680 with a lc brass.

With my 8" barrel I loaded 11.3 gr. of A1680 and got a muzzle velocity of 1,070 fps with a 219 gr bullet.

I think with the 10.2" barrel and the 208 Amax you will do fine to start at the above mentioned 10.7 and work down from there.

My guess is 10.0 gr will get you a 1020 fps. Just a guess.

What's the oal I should be shooting for? Right now I'm at 2.181

I set the calipers at 0.25 lock them and lightly score the ogive of a bullet. Then seat so that score lines up with the top of the rib in the magazine.That is how I would set seat depth for bullets in the standard GI magazines.

Dryflash3 shows some bullets marked at the .25 ogive in this post.

Reason why I have it set at that length is I measure a factory round from hornady from a box that i've been shooting.  Should I stick to that length or go by what the book says at 2.250?

If it feeds then shoot it. I would use the ogive method. But what you have done will be fine. Just watch for binding in the magazine. If the magazine is loaded and you hear bullets rattling around (after loading about 5 bullets) then they are not stacking evenly and you will need to adjust the seating depth so the ogive at .250 is at the center of the rib in the magazine. This most closely replicates 5.56 cartridge dimensions relative to magazine fit. I don't have a 208 amax handy to load and measure to determine the oal I get after seating using the .250 ogive / rib method.

If you're shooting these rounds in an AR, you need to seat the bullet to feed from an AR magazine.  Which means you need to follow the basic guidelines dryflash3 set out in the post Unkydon linked to.  This puts the appropriate portion of the bullet in the magazine so that the rib will guide the round into the chamber correctly.

I've loaded all sorts of different bullets in 300 Blackout cases, and following dryflash3's process, they have all fed fine.

Load up a dummy (no primer or powder) round following the ".250 bullet diameter" method linked above and you'll see why it works.  On the other hand, just mimicking the OAL from a factory round may or may not get it to feed in your AR, because (amazingly, to me) not all factory Blackout ammunition is loaded to work in an AR.

I've got a "new-never opened" 8lb jug of H110. Somebody I know said they'd be interested in it.


It was originally intended to be used for "supers" as I realize it's not the best choice for subs.

But do you I'd be better served to sell that and get Lil' Gun so I could use powder for subs and supers?


Thoughts?


(8.5" barrel with pistol gas system)