308, subsonic, suppressed, cast bullet tests.

Ian

Notorious member
Info is scarce on this so I made some for the internet. All disclaimers apply, don't be a dummy and if you blow up your stuff or get a baffle strike or have a Secondary Explosive Event (SEE) it's your own asphalt.

.308 Winchester, Savage 111 LH with Savage factory 20" hog rifle barrel swapped to it.
WCC-08 brass, match-prepped, necks turned, trimmed, inside VLD chamfer. NO mods to flash hole diameter.
ACE 235 grain plain-based bullets (similar to NOE 311-230) cast of 2 COWW/1 SOWW/1 soft scrap, air cooled, sized .3098", lubed with SL-68.1.
Alliant Red Dot, no filler.
Federal 210 Magnum large rifle primers.
About .003" neck tension (too much, actually), cases belled just enough to prevent shaving. Bullets seated in Forster Benchrest sliding collet die to 2.260", this puts the front band into the throat's freebore with about .020" from hard contact. NO crimp.

Range was calm, clear, very dry, and temperature about 70°F. Elevation 1600 feet, not that it matters.
7.1 grains gave me an average muzzle velocity (MagnetoSpeed) of 1030 fps for five rounds.
6.5 grains of Red Dot gave me 975 fps average.

I only tested at 15 yards because I was in a hurry, but open sights gave me 1/2" groups of three without my Form 1 suppressor installed and and literally put them all through the same hole WITH the suppressor. Also, got some stringy lube boogers on the target without the suppressor, and some black greasy dust around the groups on the paper with the suppressor. I'm switching to SL-71 next test to see if the paraffin addition doesn't make the lube fling off better. Suppressed, the 6.5 grain load sounds exactly like firing a roll cap pistol, if you take away the bullet impact noise. I shot a steel plate at 50 yards with one shot and the steel report was crazy loud compared to the report of the rifle.

Cases were fully obturated and clean except a tiny bit of soot on the necks. Primers did NOT set back but brass was pretty snug in the chamber to begin with. I had no hang-fires whatsoever and very consistent chrono numbers, BUT I didn't test powder location within the cases. All my loads were fired with the rifle horizontal and powder settled horizontally in the cases before chambering them. I intend to do more testing in this regard to see what effect powder location has on the velocity and if any ignition concerns arise. I expect powder placement will have a significant effect on accuracy and pressure.
 

Missionary

Well-Known Member
Greetings
That sounds like a good way to spend a few minutes. Thank you for a very informative read. That long torpedo should slice right through the average hog. The others will be wondering why the target pig let out a "thwap" noise.
Mike in Peru
 

JWFilips

Well-Known Member
Ian,
Your choice of Fed Mag Primers with a light load of Red Dot? Ant reason you choose those?
Jim
 

Brad

Benevolent Overlord and site owner
Staff member
I just ordered a 2 cav NOE 311230 PB. Should be good in my 300 BLK if Ian is right. He usually is?
I have lots of 4227 and 1680 to shoot under it.

Ian, you need to get a video up. That sounds like a neat rifle.
 

waco

Springfield, Oregon
Pics? I, we, need pics. Pics or it didn't happen Ian. That's what I read anyway.....
 

Rick

Moderator
Staff member
Yes very interesting. I have a question though, why the mag primer with that powder? Did you test that load with standard primers. Not saying your right or wrong cause I don't know which of course is why I'm asking. :D
 

Ian

Notorious member
I wrote a little about the rifle in Special Projects along with one cruddy picture, I was in rare form that night so you'll have to forgive me. I never have modified the rifle for an M1A or SR-25 magazine, but something like that is going to happen eventually. I'll do some more and soon I'm going to do a write-up on the Form 1 suppressor I just built.

Ok...JIM and RICK: The internet is full of "wisdom". Or not. I read a lot about subsonic .308 loadings with heavy bullets and a lot of people say to drill the flash holes to 9/64" and use magnum primers to avoid S.E.E.. I think doing that might be fine with jacketed bullets (what most people who recommend the large flash holes are shooting) but entirely the wrong thing to do with cast bullets. I chose the magnum primers for the first loads just to be "safe". I've learned a lot since I started this thread this morning.

The primer thing was bugging me. Wife took a nap and interrupted the construction project I was doing adjacent to the bedroom, so I stole out to the range again and tried some things. I found that my MagnetoSpeed will mount to the suppressor, so that simplified things.

First off, I dropped the charge to 6.2 grains of Red Dot and loaded five with Federal Magnum and five with Federal Standard rifle primers. Got 925 fps average with the standard and almost 950 average with Magnums. The Magnum group was three times the size and 24 fps faster average. All groups fired with powder "leveled out" in the case.

Next, I loaded ten with non-magnum primers and 6.6 grains of Red Dot. First five were fired with the powder settled to the REAR of the case, against the primer. That got me 985-ish FPS and a lot of deviation. Next five were fired after settling the powder against the bullet base. That got me 950 fps. Both groups had slight flyers, but the powder against primer had a smaller hole where four went and the powder against bullet had an evenly dispersed group with one wild flyer (I'm discounting it, probably a base void).

Seeing that I was getting something around 35 fps average difference between muzzle up and muzzle down with standard primers, I went back and loaded ten with magnum primers and 6.6 grains to see if it wouldn't make the powder less position sensitive. First five fired with powder against bullet this time got me 980 fps average and less than 9 ES, pretty good. Then I fired five with powder against primer and got a surprise: Group opened up a lot, ES was on both sides of the previous average, ranging from 963 to 1003 fps. Pretty drastic and seemingly opposite of what happened when orienting the powder to either end with the standard primers.

Granted, this is a small sampling, but all indications so far are that the Red Dot is going to be position sensitive no matter what, yet gives better aggregate accuracy (if up and down oriented groups are overlaid) with standard primers than the magnum primers.

I got no hint of a hang-fire with standard primers, and no difference in case neck obturation (it's pretty good with all of these loads).

I think for now I'm going back to 6.2 grains or maybe 6.4 and standard primers, and will play with lube a bit.
 

fiver

Well-Known Member
when doing low and slow with the 300 b.o. I found when switching from rifle primers to pistol primers I lost my group size and started running the ragged edge of stability at the same time.
of course 3.5 grs of powder [700-x] is right on the edge anyway.
I'm learning more about the relationship between primers and load density from that thread were are doing in the rifle section.
I wonder how another powder such as bulls-eye, tite-group, or 700-x would work for you. [coating flake size etc, will make a difference]
 

JWFilips

Well-Known Member

Ian,
I just checked out that thread...I want to comment on your photos problem. You camera meter is being fooled by the white door which comprises most of the image area: It is reading a 90 % reflecting surface and trying to underexpose to achieve an 18% gray ( that's how camera meters work) The exposure to get that photo (A good exposure on the rifle and a white background) requires you to trick the camera meter by over exposing about + 3 stops. Most cameras have a setting to achieve this
Hope you don't mind I brought the image up 3.5 stops in photoshop Not the best way because the dark areas do not have enough information but we can see the rifle better
 

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Ian

Notorious member
Thanks, Jim! I spent about a hour reading through my wife's EOS book a few years ago and started learning about the settings, but I just don't have room in my head. This Kodak has a manual setting where I can tweak all that but usually I just point and shoot to get the photo on line. That reminds me, i need to take some more shots of the camo rifles and the sun is just barely high enough yet that I can go do that right now.
 

JWFilips

Well-Known Member
Ian,
The EOS should have the provision for adjusting the Exposure + 3 to-3 stops (Even on auto mode) But as soon as you shut the camera down it will default to normal exposure
Jim
 

JWFilips

Well-Known Member
Ian:
Sorry to drift the thread: But a good rule of thumb is: If your subject is darker then the background and the background takes up more then 50% of the area..... a camera meter will try to make the majority of the brightest area in the photo "mid tone" For instance If you take a picture of your rifle on the shooting bench with the background being a snow covered field... you will need to fool the meter in the camera by at least 3 stops to get the gun to be exposed properly! No new technology I know of can make a camera see like a human eye!....Guess that is why we are still in control of this world (& not the cyborgs!)
Jim
 

Ian

Notorious member
when doing low and slow with the 300 b.o. I found when switching from rifle primers to pistol primers I lost my group size and started running the ragged edge of stability at the same time.
of course 3.5 grs of powder [700-x] is right on the edge anyway.
I'm learning more about the relationship between primers and load density from that thread were are doing in the rifle section.
I wonder how another powder such as bulls-eye, tite-group, or 700-x would work for you. [coating flake size etc, will make a difference]

I almost ran some Bullseye loads yesterday, in fact I started walking back to the house with ten empty cases in my hand and Bullseye on my mind but the thought occurred to me that maybe that was too much of a "good" thing and was worrying about SEE, so I turned around and brought everything in for the evening.

Something interesting, while studying case volume and different loads with lead bullets and pistol powders, I discovered that the data in Speer #11 for .44 Magnum and swaged lead 240-grain bullets happened to give the same results within a few FPS as .308 with 235-grain lead bullets and standard rifle primers. So I already have load data for Bullseye, 700X, Unique, HS-6, and a few others right there.
 

Ian

Notorious member
Hmmm, that's about the same thing, isn't it? .357 Magnum is comparable in volume to 300 BLK and has similar bullet weights, lots of data for cast bullets available with all sorts of powders.

I think I just psyched myself out. Stupid me forgot how many hundreds of rounds of .45 Colt I've shot that were loaded with a pinch of Bullseye in that big ol' case and set off with a standard pistol primer. Never hurt a thing except the targets. Darned accurate, too, whether shucked in from a tube magazine or brought up to fire by the next hole in the cylinder after all the powder was jolted to the front by the previous shot, or brought up to fire from a straight-down position in the holster.
 

fiver

Well-Known Member
yep if you look at some of LEE's data you'll see where they 'modified data from a similar case'.
in other words X amount of powder in a x sized cylinder gives x amount of gas expansion if the bullet weights are similar so will the pressure and velocity.
that's how I got my start data for the XCB project too.
 

Ian

Notorious member
I was amazed at how the straight .44 case and the bottleneck .308 case will deliver virtually the same results with equal charges of the fast to medium pistol/shotgun powders (BE to Unique range). Barrel length is different (6" vs 20") but I would expect the .30-caliber bullet to react a lot differently. Of course we're just looking at PEAK pressure here, not what the curve looks like and the expansion ratio is way different between the two. In the .44 the pressure will spike and fall off almost right away and I expect the .308 will stretch out a little bit longer (still short though).
 
F

freebullet

Guest
Interesting info here.

I really like red dot. In my tests in 30-30 I had inconsistent performance I attributed to position sensitivity. Nothing major but, noticeable in sound & on target. I didn't investigate further because, the titegroup loads performed better with handling of the lever. You might try similar with tg if you have any. Being such a similar case it may make the same difference in your application.
 

Ian

Notorious member
I have a couple pounds of Titegroup that I don't use in anything currently, I might have to give that a whirl. Were you using heavy bullets in the .30-30? One thing I noticed with TG in .40 S&W is when nearing the top end of a load workup the pressure got pretty up there all of a sudden.