CETME C308 Cast boolit load that cycles

[Bigmancrisler]

So I have read through a quite a few threads here and none of them seem to come to a similar conclusion. My question is, should I be using a lighter boolit (lee 312-160) or heavier (lee 312-185) which a slower powder or fast powder? I loaded up some test loads today and took it to the range and only had 1 round eject and pick up the next round.

I used 13 and 15gr of unique (didn’t do anything), 32gr of SW AR plus (didn’t do anything) 17 and 23gr of 2400 (23gr had the one round that cycled) these were all with a 185gr cast bullet PC and GC.

I would preferably have a load using the AR plus as I have about 8lbs of that while I only have a lb of the other two. I was using the data listed in the lyman CB handbook.

I know on rifles like the garand you need a heavy boolit to cycle the action to have enough dwell time. While the CETME is roller delayed I have read that it relies on the recoil impulse. I’ve never reloading for a roller delayed rifle so not really sure where I should go to next as far as testing goes. (I also wouldn’t mind a fart load like 13gr red dot if something like that will cycle).

[Thumbcocker]

I have had good luck with 4895 and a heavier boolit in a Garand and an Ar.

[Larry Gibson]

Bigmancrisler

A heavier bullets such as Lee's 200 gr or, preferably, either Lyman's or NOE's 311299 plus the use of 4895 (28 - 32 gr) with a dacron filler will give enough pressure to function the action. I'm not familiar with "SW AR" powder. If it is in the same burn range as 4895 and a ball powder, then a magnum primer or WLRs or #34s should be used with the dacron filler also.

[Bigmancrisler]

Bigmancrisler

A heavier bullets such as Lee's 200 gr or, preferably, either Lyman's or NOE's 311299 plus the use of 4895 (28 - 32 gr) with a dacron filler will give enough pressure to function the action. I'm not familiar with "SW AR" powder. If it is in the same burn range as 4895 and a ball powder, then a magnum primer or WLRs or #34s should be used with the dacron filler also.

It is pretty comparable to H335


Sent from my iPhone using Tapatalk

[WinchesterM1]

In MY HK91/G3 I use a 311299 over 25 of imr4198 and it shoots great, my rounds are PC/GC301541

[Larry Gibson]

It is pretty comparable to H335


Sent from my iPhone using Tapatalk

For such ball powders to burn efficiently a certain level of pressure is needed. That indicates the use of the heavier bullet, magnum level primer and a dacron filler is needed to put the powder into it's needed pressure range while keeping the cast bullet at 1900 fps +/- because of the 10" barrel twist.

[Bigmancrisler]

For such ball powders to burn efficiently a certain level of pressure is needed. That indicates the use of the heavier bullet, magnum level primer and a dacron filler is needed to put the powder into it's needed pressure range while keeping the cast bullet at 1900 fps +/- because of the 10" barrel twist.

So I’m going to need an even heavier bullet than 185gr?


Sent from my iPhone using Tapatalk

[Larry Gibson]

Possibly. Keep in mind with cast bullets you are using reduced pressure loads. The heavier the cast bullet with a given powder charge the higher the pressure will be. That means with the heavier bullet a lesser charge of powder can be used to reach the psi necessary for efficient burn while keeping the bullet in the 1900 fps +/- range. That will give sufficient psi to function the action. With H4895 + dacron filler under a 311299 I've found between 28-32 gr will function CETME and HK 91 actions.

[Bigmancrisler]

Possibly. Keep in mind with cast bullets you are using reduced pressure loads. The heavier the cast bullet with a given powder charge the higher the pressure will be. That means with the heavier bullet a lesser charge of powder can be used to reach the psi necessary for efficient burn while keeping the bullet in the 1900 fps +/- range. That will give sufficient psi to function the action. With H4895 + dacron filler under a 311299 I've found between 28-32 gr will function CETME and HK 91 actions.

Then why does the lyman cast bullet handbook list some velocity’s as high as 2400 fps?


Sent from my iPhone using Tapatalk

[Winger Ed.]

Not quite the same as a Garand, but--
I shoot cast in a M1A and have had good luck with IMR 'stick' powders and a 170RN with a Hornady gas check.
IMR 4198 is the powder I keep coming back to.

I can't remember exactly how much, but I worked up until it just cycled.
Then went up one more grain, which was still noticeably below max.

[Bigmancrisler]

Not quite the same as a Garand, but--
I shoot cast in a M1A and have had good luck with IMR 'stick' powders and a 170RN with a Hornady gas check.
IMR 4198 is the powder I keep coming back to.

I can't remember exactly how much, but I worked up until it just cycled.
Then went up one more grain, which was still noticeably below max.

I already have a load that cycles my garands (lee 312-160 and 30gr H335) I just don’t have more than like 1/2lb of IMR4895 and I’ve yet to see any of that on a shelf anywhere (I have a LGS that basically only Carry reloading supplies and they haven’t had any IMR powder in like a year or so.


Sent from my iPhone using Tapatalk

[Larry Gibson]

Then why does the lyman cast bullet handbook list some velocity’s as high as 2400 fps?


Sent from my iPhone using Tapatalk

Because, as stated in the "fine print" in the Lyman manuals, the selected loads are based solely on the internal ballistic uniformity keeping under what they consider maximum loads. Lyman has not tested any loads for on target accuracy in many years. Even back in the day when they did it was only at 50 yards.

[Larry Gibson]

I already have a load that cycles my garands (lee 312-160 and 30gr H335) I just don’t have more than like 1/2lb of IMR4895 and I’ve yet to see any of that on a shelf anywhere (I have a LGS that basically only Carry reloading supplies and they haven’t had any IMR powder in like a year or so.


Sent from my iPhone using Tapatalk

Work with your AR powder. Use a magnum level primer and a dacron filler to enhance ignition and burn rate. Suggest you try with the 185 bullet, it might work, only your rifle will tell.

[Bigmancrisler]

Because, as stated in the "fine print" in the Lyman manuals, the selected loads are based solely on the internal ballistic uniformity keeping under what they consider maximum loads. Lyman has not tested any loads for on target accuracy in many years. Even back in the day when they did it was only at 50 yards.

Ohhh ok, that makes more sense, cause it has a little note saying which load happened to be the most accurate for them


Sent from my iPhone using Tapatalk

[Bigmancrisler]

Work with your AR powder. Use a magnum level primer and a dacron filler to enhance ignition and burn rate. Suggest you try with the 185 bullet, it might work, only your rifle will tell.

Should I just slowly bump the Dacron filler up until it it shows more promise?


Sent from my iPhone using Tapatalk

[Larry Gibson]

https://castboolits.gunloads.com/showthread.php?109280-The-proper-use-of-fillers

Post #2 will give you a good description of the proper use of the dacron filler. Here is the basic information;

The “dacron” is polyester fill as commonly found in pillows and toys. It also comes in sheets called “batting”. It can be obtained very reasonably at most any fabric store.

The dacron batting comes in various thicknesses. I prefer that which is about 5/8" thick. My wife recently bought me 10 yards which will give many, many thousands of cast bullet loads. With this current batch of batting I cut it initially across the width into strips about 3/4" wide. I then "eyeball" cut 1/2" wide chunks which is close to 3/4 gr.

A smaller chunk is cut for 1/2 gr and larger for a larger amount. I've cut some chunks that weight 1/2, 3/4, 1, 1 1/4 and 1 1/2 grs and have them in a "snack" baggie stuck on a poster board above my loading bench for quick reference when I need to cut new chunks. The batting will run thin and thick throughout the sheet so I again just "eyeball it" based on the thickness of the batting when cutting the chunks.

Pretty extensive tests have demonstrated that the weight of the filler does not have to be exact, only close. What is important is that there is enough so that it “fills" the space between powder and bullet. A little too much hurts nothing but too little poses problems. That's why I have the different size "chunks" so I can use the right size for the case capacity I am filling. For example; with most medium burning powders (3031, 4895, 4064) in and '06 to function an M1 a 3/4 gr dacron filler is about right. With slower powders that give a higher loading density like 4831 a 1/2 gr filler is about right.

I use a section of .22 cal cleaning rod in cartridges of .30 - .375 cal to push the Dacron chunk inside the case just so it is all in. The 6 to 10" section gives plenty to hold onto and sufficient "feel". Merely hold the chunk of dacron over the case mouth and shove it in with the rod. Sometimes it takes a couple three pokes to ensure all is inside the case mouth. I poke the chunks in until all the dacron is at the bottom of the neck or at least all in the case. It doesn’t matter exactly where just so long as you don’t tamp it down on the powder as a wad and leaved a space between the base of the bullet and the dacron.

What you want to do is push it in to let the base of the bullet finish pushing it down and adding any compression against the powder. Thus, I do not push it down on the powder but let the bullet do that when the bullet is seated. Using the right size chunk of dacron this method then provides a "filler" in the air space between the powder and base of the bullet as the dacron will "fluff" back up to fill the air space. Just don't tamp it down on the powder making it a wad.

[winelover]

I've tried a lot of different powders and cast bullets with my Armalite AR10 carbine. My best groups were with Reloader 15 and NOE's 160 Spitzer. Conventionally, lubed and oven heat treated. I don't PC.


301596


Never got good groups with cast bullets heavier than 180 grains. Those that cycled the action 100% of the time, anyways. Some report good results with Varget........didn't pan out for me. There isn't much cast bullet data out there for use in semi auto rifles. Your pretty much on your own.

Winelover

[Bigmancrisler]

https://castboolits.gunloads.com/showthread.php?109280-The-proper-use-of-fillers

Post #2 will give you a good description of the proper use of the dacron filler. Here is the basic information;

The “dacron” is polyester fill as commonly found in pillows and toys. It also comes in sheets called “batting”. It can be obtained very reasonably at most any fabric store.

The dacron batting comes in various thicknesses. I prefer that which is about 5/8" thick. My wife recently bought me 10 yards which will give many, many thousands of cast bullet loads. With this current batch of batting I cut it initially across the width into strips about 3/4" wide. I then "eyeball" cut 1/2" wide chunks which is close to 3/4 gr.

A smaller chunk is cut for 1/2 gr and larger for a larger amount. I've cut some chunks that weight 1/2, 3/4, 1, 1 1/4 and 1 1/2 grs and have them in a "snack" baggie stuck on a poster board above my loading bench for quick reference when I need to cut new chunks. The batting will run thin and thick throughout the sheet so I again just "eyeball it" based on the thickness of the batting when cutting the chunks.

Pretty extensive tests have demonstrated that the weight of the filler does not have to be exact, only close. What is important is that there is enough so that it “fills" the space between powder and bullet. A little too much hurts nothing but too little poses problems. That's why I have the different size "chunks" so I can use the right size for the case capacity I am filling. For example; with most medium burning powders (3031, 4895, 4064) in and '06 to function an M1 a 3/4 gr dacron filler is about right. With slower powders that give a higher loading density like 4831 a 1/2 gr filler is about right.

I use a section of .22 cal cleaning rod in cartridges of .30 - .375 cal to push the Dacron chunk inside the case just so it is all in. The 6 to 10" section gives plenty to hold onto and sufficient "feel". Merely hold the chunk of dacron over the case mouth and shove it in with the rod. Sometimes it takes a couple three pokes to ensure all is inside the case mouth. I poke the chunks in until all the dacron is at the bottom of the neck or at least all in the case. It doesn’t matter exactly where just so long as you don’t tamp it down on the powder as a wad and leaved a space between the base of the bullet and the dacron.

What you want to do is push it in to let the base of the bullet finish pushing it down and adding any compression against the powder. Thus, I do not push it down on the powder but let the bullet do that when the bullet is seated. Using the right size chunk of dacron this method then provides a "filler" in the air space between the powder and base of the bullet as the dacron will "fluff" back up to fill the air space. Just don't tamp it down on the powder making it a wad.

Thanks for the information! I’ll have to give it a try. I’ve always been a bit nervous about using Dacron as I didn’t want to accidentally cause something dangerous to happen.


Sent from my iPhone using Tapatalk

[Bigmancrisler]

So after further testing, I ended up getting a Lee 312-160 pill with 30.5gr of AR Plus to cycle reliably. It ejected brass about 3-5 feet to the 2 o’clock. It shot POA POI at 100 yards and was surprisingly accurate. Not sure how fast it was going as I didn’t chrono it. But I’m more than happy with this.


Sent from my iPhone using Tapatalk

[Thumbcocker]

Glad to hear it worked out for you.