300 Blackout Cast Questions

[steve4102]

I know, I know the Blackout again, sorry, I did a search and read till my eyes were bleeding and I still have questions.

Some info. This is my first attempt at loading cast rifle bullets, been loading cast pistol for awhile, but never rifle.

My mold is Lee C312-155-2R, I coat them twice with HI-TEK, then size to .309 in a Lee sizing die and seat the Gas Check, then I coat them a third time. The rifle is a M&P 16 inch Carbine.

My first question is about seating the GC. Is applying the GC with the Lee sizing die sufficient? I looks fine to me, and I have to use a pliers and small screwdriver to remove.

How fast can I push these HI-TEK coated GC bullets? I went to the range today and chronyed some test loads and there ranged from 1800-1900fps. Some loads were OK as far as accuracy, some really stunk. I was wondering if going above 1900fps is a good idea in my quest for accuracy or should I stay at or below 1900fps?

Powders tested were 296/110, Lil Gun and 1680. 296/110 was pretty good with 2 inch at 100 yards (four shots) Lil-Gun flat out stunk, (4-5 inches was the norm), 1680 wasn't bad, but it wasn't good either, I will have to test that one again later.

I have a few other powders that might work in the Blackout, but data seems a bit scarce, specially for cast. Besides the three mentioned above I have 2400, N-200, R-7, both 4198s and VV N-120. I would really like to give R-7 a try, but I can't find any data.
When faced with only jacketed data, how do you proceed? Start Low and work up, I know, but how far do you work up and how far do you go below Start if at all?

Thanks

[petroid]

What is your alloy? Barrel twist? Harder bullets may be needed with fast twist. I know my 1:7 loses accuracy above about 1800 with that mold using quenched wheel weights.

[steve4102]

Allow = Straight Wheel Weights

Twist = 1 in 7.5

[Jupiter7]

You aren't gonna get much more velocity, 2k is roughly it with 150's. Try slowing them down for better accuracy.

[GabbyM]

1800fps and above is to fast for a 1: 7 1/2 inch twist with cast. RPM to high.

That twist rate is for sub sonic loads. Even with a standard 30-06 twist rate of 1:10" the limit for great accuracy with no fliers is 1,950 fps. pertiod says he get up to 1,800 fps and I'm surprised he gets that high. Load for under that then see how they shoot. My thought from the top of my head would be around 1,650 fps from a 7.5" twist. Then if you get that with accuracy your bullets are OK. For a high velocity AR in 30 the 7.62 WT with a 12" twist gets you there with a 150 grain flat nose. Even that chamber is not set up for cast boolits. Not to despair. 1,600 will get you to 100 yards in a heart beat. It is what it is.

I am currently fixing up a package of Lyman #311299 boolits 200 grain SP to send to my son in law for his BO pistol. Sub sonic play with a can. I can't own such a toy here in Illinois.

[steve4102]

Thanks, I'll slow them down a see what shakes out.

[steve4102]

No chrony data today, snowing to hard.

296/110, 14.8gr left, 15gr right.
100 yards.

Red squares measure 1 inch.

Thoughts?

http://i2.photobucket.com/albums/y17/steve4102/IMG_1247_zps2rpaaong.jpg

[MT Chambers]

I use 17.5 grains of RL-7 in my bolt action rifle, with 160-180 gr cast boolits, all my shooting with the whisper has not resulted in the kind of cast bullet accuracy one would expect, and I expected at least 1" or less with the super accurate setup I have.

[flyingrhino]

155926Lee C312-155-2R pc'd then sized to .309. GC installed during sizing in Lee push through. One coat PC. 17 gns IMR4227 seated 2.055. AR-15 16" 1-8 twist. Chrono'd 1884 FPS. That's 3 shots at 50 yards just to see if this load would be on paper. It shoots under 1" groups at 100. I pushed it to 1950 fps with 17.3 gns and experienced a small amount of leading so backed it back down to 17. This was my very first try at working a load up for the 300 BO and was astonished that my first attempt was a bug hole.

[popper]

I tried HiTek gold in 308 @ 2700, 170gr GC, too many fliers. Attempts to use it in BO @ 1700 with a plain base boolit (145 gr) were futile also, but I think that is due to the application. Both are 1:10, both work great PCd. Boolits are H.T.d isocore, about the same as WW. I definitely would try to coat 3x then GC & size. RL7 & 4227 were OK but 110 works best for me.
Gabby please show some results with the 40WT, 150 or heavier boolits. Can't decide if it will do me any good. I've got a 170 mould Id like to use.

[dimaprok]

155926Lee C312-155-2R pc'd then sized to .309. GC installed during sizing in Lee push through. One coat PC. 17 gns IMR4227 seated 2.055. AR-15 16" 1-8 twist. Chrono'd 1884 FPS. That's 3 shots at 50 yards just to see if this load would be on paper. It shoots under 1" groups at 100. I pushed it to 1950 fps with 17.3 gns and experienced a small amount of leading so backed it back down to 17. This was my very first try at working a load up for the 300 BO and was astonished that my first attempt was a bug hole.

I know this is old post, but what alloy did you use? Did you measure BHN by any chance? My best result was 1.36" at 50 yards and the rest were 2-3 inches and I was pretty frasturated. I am using wheel weights but my bullets might be too soft. I am in process of trying heat treating.

[flyingrhino]

I know this is old post, but what alloy did you use? Did you measure BHN by any chance? My best result was 1.36" at 50 yards and the rest were 2-3 inches and I was pretty frasturated. I am using wheel weights but my bullets might be too soft. I am in process of trying heat treating.

These were clip on wheel weights. They were water dropped but the process of PC'ing pretty much removes any hardness gained by water dropping. I have tested them for BHN but don't remember what they are. They aren't very hard. Personally, I think heat treating is over rated unless you are really trying to push lead really fast without gas checks. My subs are not gas checked but they are only running 1000-1100 fps. All of my supers are gas checked.

You don't mention what bullet, powder, etc. you are using. Post your specs like I did. Someone might be able to see something that you can improve on.

[dimaprok]

This is what I am struggling with lately. I was casting for revolver and powder coating and all was fine and dandy until I started casting for 300 BLK this summer for the first time and all of a sudden I got one somewhat OK group, but rest was horrendous. I tried different powder and bullet combination and 2 more outings and all terrible, I almost threw in the towel. From the start I made my own gas checker and was experimenting with that as well. I got advice from one person that GC is dead, just powder coat and shoot, well that didn't turn out good, after like 5 outings shot all my development loads and last one was tumble lubed RCBS 115gr 5x bullets that I gas checked and I made 0.38" group 4 shots minus 1 flyer. It was my last group for the day and I was blown away, it was best group with this gun, I am shooting bolt action Ruger 300 BLK. So I learned few things. 1) Yes, so far gas checks shown better accuracy. 2) for this particular bullet seating to the middle (lube grove) made a huge difference, also I tested alloy at home from the same batch and it ran from 15.4 - 17.9, these were water quenched. 3) I need to powder coat thinner layer and play with low temp so it doesn't destroy water quenching tempering. Elvis Ammo on youtube made a video about it. 4) I am using CFE BLK powder because it produces considerably less pressure. I tried your load of 17gr 4227 and with 3 shots I got 1.44" all shot at 50 yards. With 155gr bullet my best result today was 1.2" It's an improvement, last time it was 1.4" with 19gr CFE BLK. I noticed in my notes my seating depth was 1.990" at top of crimping groove and yours was 2.055" so you must be sitting at lower lube groove, I need to try this, as well as other powder amounts. I should also add I modified this mold and faced off gas check portion resulting in flat based bullet at 136gr +/- 1gr. So far best I got 0.8" 5 shots - not bad actually. Than I decided to use rimmer and remove lube grooves for flat side bullet, but I screwed up, I was impatient. It still looks somewhat ok after resizing, it produces 141gr bullet and my goal was to produce about 130gr bullet with straight sides for powder coating, it also feeds very nice like 155gr one. The 115gr doesn't feed reliably because it's too short. My best results with this 141gr was 1.26". Do you crimp? I used light Lee factory crimp this time.