Compressed loads question

[Tenntrapper]

Having never loaded a compressed load, I am confused about this. If your load says it's 103 percent case fill, how do you get all the powder in there to compress it?
Can someone explain this?
Thanks

 

[backyardtndeer]

Will be interested in hearing replies to this. Would assume that you load and tamp down powder or press it in with your bullet, but this is purely a guess.

Seems it may be dangerous whatever the process.

 

[DaveB]

You just did. The powder fills the case up such that when seating the bullet you will feel, and most likely hear, the powder being scrunched together-compressed. For the record, I measure every round when loading compressed powder charges. I have also been known to tap the brass with my loading pan from bottom to top to settle the powder. My BIL holds his finger over the mouth and sets the charged brass on his jogger.

Almost never happens with flake powders (like H335) and nearly always seems like with extruded ones like IMR7828, 4350, & quite a few others.

110% is not unusual, it is safe (modern bolt firearms), and very very frequently it produces the most consistency between shots and the best accuracy.

 

[TiminTN]

Depending on your brass, as it varies in thickness brand to brand, compressed loads can cause irratic oal, due the powder resisting seating pressure. I stay away from compressed loads.

 

[kamml]

You can buy extended loading funnels that will drop extended loads pretty much into the case

 

[Tenntrapper]

You just did. The powder fills the case up such that when seating the bullet you will feel, and most likely hear, the powder being scrunched together-compressed. For the record, I measure every round when loading compressed powder charges. I have also been known to tap the brass with my loading pan from bottom to top to settle the powder. My BIL holds his finger over the mouth and sets the charged brass on his jogger.

Almost never happens with flake powders (like H335) and nearly always seems like with extruded ones like IMR7828, 4350, & quite a few others.

110% is not unusual, it is safe (modern bolt firearms), and very very frequently it produces the most consistency between shots and the best accuracy.

So, it's not more than will fit in the case? It's 103 percent (my example) of case fill, with bullet seated?


Would it be possible loading for rifle with long throat (seating bullet further out) for a "compressed load" to not really be compressed?

 

[KPH]

So, it's not more than will fit in the case? It's 103 percent (my example) of case fill, with bullet seated?


Would it be possible loading for rifle with long throat (seating bullet further out) for a "compressed load" to not really be compressed?

If the recipe states a compressed load I would compress it.

 

[Tenntrapper]

If the recipe states a compressed load I would compress it.

This is all hypothetical right now. I'm just trying to understand what it is.
So if a given rifle has a longer throat than their test barrel, so much so that you need to seat farther out for accuracy reasons, and that results in the load not being compressed, then you should avoid that load?

 

[MUP]

This is all hypothetical right now. I'm just trying to understand what it is.
So if a given rifle has a longer throat than their test barrel, so much so that you need to seat farther out for accuracy reasons, and that results in the load not being compressed, then you should avoid that load?

Not at all. I have a 300 WinMag that the 220 gr bullets, seated .040" off the lands, give the OAL of the round about .150" more than SAAMI specs from a factory round. This is likely keeping me from having a compressed load in this rifle. There is no shake of the powder once loaded, so it's likely a compressed load for a shorter throated barrel. I also have basically zero clearance from those rounds in the magazine either tho, something else to watch for, or you'll end up with a 2 shot rifle.

 

[Hunter 257W]

Kamml hit on the answer to "compressed" loads. A drop tube funnel will allow more powder to fit in the case so a slightly compressed load (per the load manual) will fit without crunching powder. The only compressed loads I've used were in my 460 Weatherby. Can't recall if it is 4350 or 4831 but the max load is about 1/2 way up the neck. You can hear the crunching when you seat the 500 grain Hornady down below the shoulder. It's a good thing too in a heavy recoiling rifle because it keeps the bullet from being driven back into the case from recoil slamming the bullet into the front of the magazine box. A heavy crimp is also used to keep the powder from pushing the bullet out.

Trying to seat the bullet further out to compensate for a powder charge listed as over case capacity might help a bit if your magazine and throat dimensions allow. Although for me, I'd try the drop tube funnel and seat the bullet to a normal depth myself.

 

[Tenntrapper]

Please let me clarify a couple things. My initial understanding of a compressed load, let's say was 103 percent case fill. I thought that meant that if the case was completely full, 3 percent would still be outside the case. I was trying to figure out how you got the powder in there, to compress it. Now, my understanding is that the 103 percent, is based on the case volume with the bullet seated to their coal. I haven't attempted a compressed load, as I've avoided them from lack of understanding.
Loading long to avoid a compressed load was not the question. The question was, if you loaded long for other reasons, and this resulted in the charge not being compressed, would this be a problem? The answer given doesn't really make sense to me, as loading longer would result in more case volume, hence lowering pressure for the given charge.
The example cartridge I was using was the 6.5x55. it is an intermediate cartridge that is always chambered in a long action. There is plenty of room to load long. As to throat depth, some have really generous throats. On my CZ, you can load 160g to look like lawn darts, whereas 120s won't be in the case at all if you try to touch the lands.
This was all hypothetical. No firearms, shooters, cats, dogs, or pygmy rabbits were harmed in the asking of this question. I was just trying to get a better understanding of what a compressed load was....103 percent, is a 103 percent of what?
And that answer has to be...of the case volume with the bullet seated to their coal.
Any further explanation would be appreciated.
Thanks

 

[DaveB]

103% applies to the SAAMI specs only. SAAMI determines how much pressure the ignited charge will generate (in a proof barrel) and modified that number down to achieve safety in a typical production rifle. The ammo/powder manufacturers backfill the powder charge numbers to achieve the desired result (accuracy with no pressure signs). For example: I can put 25 gr of H335 in a 223 case and have plenty of room. But if I fill the case to 103% using H335 I have created a disaster. Pressure would far exceed SAAMI numbers.

If you load long the case capacity is increased (past the SAAMI spec) BUT you would STILL BE 103% just not compressed as much or at all.

And nothing wrong with that. When in doubt, check multiple sources. If still in doubt, work up to 103 looking for pressure signs. Just because powder X can be loaded to 103% of SAAMI case capacity DOES NOT mean another powder for the same cartridge can be loaded to 103%.

Compressed loads indicate a powder charge that exceeds SAAMI specs and in some rifles may not be safe. And if the compressed charge is borderline safe and someone throws an overcharge of a few grains, disaster could result in a modern rifle.

This is exactly why I own a forester collet bullet puller and a collet for every caliber. I have zero qualms about pulling as many as 100 rounds when I have found an error.

 

[Tenntrapper]

103% applies to the SAAMI specs only. SAAMI determines how much pressure the ignited charge will generate (in a proof barrel) and modified that number down to achieve safety in a typical production rifle. The ammo/powder manufacturers backfill the powder charge numbers to achieve the desired result (accuracy with no pressure signs). For example: I can put 25 gr of H335 in a 223 case and have plenty of room. But if I fill the case to 103% using H335 I have created a disaster. Pressure would far exceed SAAMI numbers.

If you load long the case capacity is increased (past the SAAMI spec) BUT you would STILL BE 103% just not compressed as much or at all.

And nothing wrong with that. When in doubt, check multiple sources. If still in doubt, work up to 103 looking for pressure signs. Just because powder X can be loaded to 103% of SAAMI case capacity DOES NOT mean another powder for the same cartridge can be loaded to 103%.

Compressed loads indicate a powder charge that exceeds SAAMI specs and in some rifles may not be safe. And if the compressed charge is borderline safe and someone throws an overcharge of a few grains, disaster could result in a modern rifle.

This is exactly why I own a forester collet bullet puller and a collet for every caliber. I have zero qualms about pulling as many as 100 rounds when I have found an error.

Thanks for the info daveb. I thought the 103 percent of case capacity was based on case capacity with that bullet seated to their specs. Where I get lost...if you had a short throated chamber, and had to seat deeper, then obviously that same charge would take up more than 103 percent of it. Likewise, the same bullet seated longer would increase the capacity, thus reducing the percentage of used case capacity. Maybe I'm not explaining my confusion clearly. EXAMPLE would be..a gallon of water is a less percentage in a swimming pool than it would be in a thimble. That is a gross exaggeration..but shows my question. Unless you are saying the 103 percent is of max pressure..which is not my understanding.
I'm not trying to do anything other than to understand. I have no loads in mind, nor am I trying to do anything that's not a listed load. With all of my loads, I start low and work up. I almost always never push to published max anyway. I was just curious how you were supposed to get that extra powder in there to compress. (Under my old assumption that it was capacity without a bullet seated).

 

[jason2779]

I have came into possession of some 6mm and 6mm magnum rounds that was a great friend of mine that recently passed away was going to get the guns but his nephew wanted the guns they where his favorites so I let the nephew have them, in memory of his uncle they are reloads but this guy was a great reloader taught me a lot and he only shot the loads he reloaded so I know they are good rounds if anyone is interested send me a message.

 

[Tenntrapper]

I have came into possession of some 6mm and 6mm magnum rounds that was a great friend of mine that recently passed away was going to get the guns but his nephew wanted the guns they where his favorites so I let the nephew have them, in memory of his uncle they are reloads but this guy was a great reloader taught me a lot and he only shot the loads he reloaded so I know they are good rounds if anyone is interested send me a message.

Jason2779, You may want to put this in classifieds, or pay it forward. Not many will see it in a thread about compressed loads.

 

[Hunter 257W]

TennTrapper, when a loading manual quantifies a load as being over 100% case capacity, it is talking about the volume of powder being greater than the literal volume of the case , it has nothing do with the pressure. All the loads in a published manual will be within normal pressure limits. However due to variations in density the various powders will fill the case more or less full. The bulky slower burning ones may over fill it and be rated as 100%+ case capacity. I can't recall exactly where on the case that nominal capacity is measured but it is standardized at least for each cartridge. If it were to the base of a bullet, you'd still need to know which bullet seated to what over all length. You don't really need to know that detail to reload though. The main thing is that it's a good thing to choose a powder that is close to 100% capacity for less variation in powder position. For large case older cartridges that were designed for black powder it's good to use the bulkier powders to best avoid double charges. The 45 Colt is one of my favorites and that gapping powder chamber can look mighty empty with a light load of some of the faster "shotgun" powders.

The 460 Weatherby loads i mentioned above were listed in loading manuals and were listed as compressed loads. They were definitely not something I tried on my own but were approved pressure tested loads. They left little room at all and powder is way up the neck of the case.

 

[fairchaser]

You can use a electric toothbrush or similar vibrating messager to settle the powder into the case. You can actually watch it go down. This eliminates a lot of uncomfortable crunching. Your bullet is now reading for seating to the desired depth for optimum performance.

 

[Tenntrapper]

TennTrapper, when a loading manual quantifies a load as being over 100% case capacity, it is talking about the volume of powder being greater than the literal volume of the case , it has nothing do with the pressure. All the loads in a published manual will be within normal pressure limits. However due to variations in density the various powders will fill the case more or less full. The bulky slower burning ones may over fill it and be rated as 100%+ case capacity. I can't recall exactly where on the case that nominal capacity is measured but it is standardized at least for each cartridge. If it were to the base of a bullet, you'd still need to know which bullet seated to what over all length. You don't really need to know that detail to reload though. The main thing is that it's a good thing to choose a powder that is close to 100% capacity for less variation in powder position. For large case older cartridges that were designed for black powder it's good to use the bulkier powders to best avoid double charges. The 45 Colt is one of my favorites and that gapping powder chamber can look mighty empty with a light load of some of the faster "shotgun" powders.

The 460 Weatherby loads i mentioned above were listed in loading manuals and were listed as compressed loads. They were definitely not something I tried on my own but were approved pressure tested loads. They left little room at all and powder is way up the neck of the case.

Thank you hunter 257, I think you answered my question. I knew it had nothing to do with pressure. Your comment about a case having a "normal" capacity, and where it is measured, answers the question. I was assuming that "100 percent" would be at top of neck...just like they do with the water. I understand how it would compress with seating the bullet, I just didn't understand how you got the extra 3 percent in there to compress. That is how I came up with the assumption that it had to be with the bullet seated to their coal. You are saying, if I understand correctly, that each case has a predetermined "full" level, that isn't actually to top of neck. Correct?

 

[Hunter 257W]

Thank you hunter 257, I think you answered my question. I knew it had nothing to do with pressure. Your comment about a case having a "normal" capacity, and where it is measured, answers the question. I was assuming that "100 percent" would be at top of neck...just like they do with the water. I understand how it would compress with seating the bullet, I just didn't understand how you got the extra 3 percent in there to compress. That is how I came up with the assumption that it had to be with the bullet seated to their coal. You are saying, if I understand correctly, that each case has a predetermined "full" level, that isn't actually to top of neck. Correct?

You know I was driving to town a while ago and it came to me that I was wrong in what I told you. You are correct that when load density is discussed, 100% case capacity is the capacity when loading the specific bullet in the manual seated to the depth required to achieve the overall length listed. I'm trying to recall how they used to discuss the amount of compression years ago when a manual didn't specify the brand of bullet but only listed a weight. Maybe they didn't try to quantify how much it was compressed? I still use a lot of loads that don't show a particular bullet but only list the weight so I still think in those terms a lot of the time.

 

[Tenntrapper]

You know I was driving to town a while ago and it came to me that I was wrong in what I told you. You are correct that when load density is discussed, 100% case capacity is the capacity when loading the specific bullet in the manual seated to the depth required to achieve the overall length listed. I'm trying to recall how they used to discuss the amount of compression years ago when a manual didn't specify the brand of bullet but only listed a weight. Maybe they didn't try to quantify how much it was compressed? I still use a lot of loads that don't show a particular bullet but only list the weight so I still think in those terms a lot of the time.

So, we are back to... capacity of case with specified bullet, seated to achieve specified coal?
I'm going to go with this, as it makes sense to me and is something that I can visualise. Thank you so much for helping to understand. Its much appreciated.