Compressed Loads, A5744

[BoomerVF14]

Been struggling to find informative discussions on this subject here or in other forums. Consensus on compressed loads seems to be: "Compression is OK. A little is good. Too much is bad." (I'll concede perhaps my web search techniques are lacking.)

Can anyone provide some guidance and expertise on how to tell the difference between "OK" and "too much" compression? Asking because I'm loading Accurate 5744 and almost every 300BLK load requires compression. The granules are (relatively) massive and difficult to meter as they keep clogging the chute in my powder measure.

I've plotted 100% fill curves by priming a spent case and loading various charges, tapping vigorously to settle, then resting a bullet on the powder and taking a COAL. It's obviously not very precise but it gets me in the ballpark. Then I compare whatever my actual charge is against the 100% number.

Does anyone else do this or am I being too much of a nerd? Is there a percentage where compression goes from good to bad? So far I've gone to ~114% without any pressure signs. But that's only around 19 grains and the published loads go up to 21 (127% by my estimate).

I get the feeling I just have to continue to increase compression little by little until signs show. But I start to get nervous in the loading phase when I'm doing the actual compression - what are the risks? At the risk of asking a dumb question, would there come a point where I compress so much the cartridge lights off?

[dellet]

The best way to test if powder will ignite with just compression is to put about 1/2 grain on an anvil and hit it with a hammer. This powder should not be compressed.



On a serious note you have the basics.

The more you compress, the slower you want to seat the bullet. This allows the powder to move and air to bleed if it can. There are a few potential problems with compressing too much. Powders like Trail Boss are very spongy so they are very frustrating sometimes. They can push the bullet back out over time. All powders can do it, so let them stand as much as a day or two and remeasure COL. The other thing that can do is bullet jump when chambering, you not only have the bullet inertia to deal with, you basically have a spring trying to force it out. These are things to be aware of and check.

If primers are not tight, they can be forced out.

Too much compression can bulge a case enough so it won’t chamber.

In theory you can crush the powder enough to change the burn rate, that’s a lot of crush. I have read about it and been warned, never seen it. Like any other dense load I have seen where chronograph numbers start looking weird, high ES or velocity flattens out. Generally not to long after velocity quits going up, you get a huge spike. The idea is to stop before the spike.

A drop tube will be your friend, the slower you pour, the more settled the powder will be.

I use load density because that is the standard term for most Shooters. Black powder shooters compress the crap out of loads and it’s generally referred to in the amount of actual compression. I am more comfortable with that. It seems more exact, or have more meaning. I compress 296 up to .010”, 1680 up to .025”. Flatbase bullets less than boat tails. Just work out something that is consistent. The amount of compression is similar to case capacity in how it effects the load.

If you take the handle out of your press or use an arbor press, you can get a feel of when compression starts. If you go through some of your favorite loads, you will find some you have been shooting for years that are compressed and did not know it. If you go to the links to powder manufacturers in handloading and if the old accurate powder links are still good, you will see that it was only recently they stared marking compressed loads.

1680, 5744, CFE BLK are good powders to learn with. They are predictable and don’t really spike. Ball powders like 1680, if you get a good drop and settle, you won’t get much compression. It will be like trying to compress a heavy punching bag.

It’s not something to be afraid of, only more aware.

Hope that helps get you started.

[SIMJOSH1]

Been struggling to find informative discussions on this subject here or in other forums. Consensus on compressed loads seems to be: "Compression is OK. A little is good. Too much is bad." (I'll concede perhaps my web search techniques are lacking.)

Can anyone provide some guidance and expertise on how to tell the difference between "OK" and "too much" compression? Asking because I'm loading Accurate 5744 and almost every 300BLK load requires compression. The granules are (relatively) massive and difficult to meter as they keep clogging the chute in my powder measure.

I've plotted 100% fill curves by priming a spent case and loading various charges, tapping vigorously to settle, then resting a bullet on the powder and taking a COAL. It's obviously not very precise but it gets me in the ballpark. Then I compare whatever my actual charge is against the 100% number.

Does anyone else do this or am I being too much of a nerd? Is there a percentage where compression goes from good to bad? So far I've gone to ~114% without any pressure signs. But that's only around 19 grains and the published loads go up to 21 (127% by my estimate).

I get the feeling I just have to continue to increase compression little by little until signs show. But I start to get nervous in the loading phase when I'm doing the actual compression - what are the risks? At the risk of asking a dumb question, would there come a point where I compress so much the cartridge lights off?

Hey bud... I been using a5744 with these Gold Dot 150 blks.. I'm def a bit over published but worked up so I felt safe... Your posts got me second thinking that though.

I use a 15" drop tube and pore slow..


What weight bullet you using at 19gns?s

[BoomerVF14]

I've run both the 110gr Varmageddon and the 125gr BT from Nosler up to 19.0gr so far.

[BoomerVF14]

The more you compress, the slower you want to seat the bullet.

If you take the handle out of your press or use an arbor press, you can get a feel of when compression starts.

All powders can [push the bullet out after seating], so let them stand as much as a day or two and remeasure COL.

I have seen where chronograph numbers start looking weird, high ES or velocity flattens out. Generally not to long after velocity quits going up, you get a huge spike. The idea is to stop before the spike.

A drop tube will be your friend, the slower you pour, the more settled the powder will be.

I'm shamelessly echoing hundreds of 300BlkTalk members when I say "Thanks Dellet!" I'll take that onboard.

Also, my 100% fill COAL baseline technique looks like an analog of the load density method you mention, so that's edifying. I'm just converting the length unit into a percentage, same idea unless I'm misreading.

I've already replaced my Forster handle with the shorter knob attachment so I think I can start working on a good reference point for compression as I continue to build charges up incrementally.

Again, thanks for the thoughtful reply.

[dellet]

The more you compress, the slower you want to seat the bullet.

If you take the handle out of your press or use an arbor press, you can get a feel of when compression starts.

All powders can [push the bullet out after seating], so let them stand as much as a day or two and remeasure COL.

I have seen where chronograph numbers start looking weird, high ES or velocity flattens out. Generally not to long after velocity quits going up, you get a huge spike. The idea is to stop before the spike.

A drop tube will be your friend, the slower you pour, the more settled the powder will be.

I'm shamelessly echoing hundreds of 300BlkTalk members when I say "Thanks Dellet!" I'll take that onboard.

Also, my 100% fill COAL baseline technique looks like an analog of the load density method you mention, so that's edifying. I'm just converting the length unit into a percentage, same idea unless I'm misreading.

I've already replaced my Forster handle with the shorter knob attachment so I think I can start working on a good reference point for compression as I continue to build charges up incrementally.

Again, thanks for the thoughtful reply.

I don’t know of any load data that will give you compression numbers in thousandths of an inch.

I try to have micrometer seating stems in all my seating dies, and none of those measure in percentages.

Quickload, Nosler is another, will give load density in percentages I wish everyone would list it.

What you might find, and why I like to use crush (for lack of better word) is that sooner or later you will crush a bullet, or bulge a case. With a micrometer type stem you can keep compressing until you mark a bullet, then back off .0X0. That number will be pretty consistent for that powder as long as your powder drops are consistent.

What numbers you use don’t really matter, as long as you can develop a repeatable system that is not starting from scratch every time.