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I'm new to reloading and have seen several people mention compressed loads and have a few questions. Is a compressed load a load where the load manual lists the load density greater than 100%? Is a compressed load more prone to greater pressure spikes as the load is slightly increased? Could seating the bullet slightly deeper with a compressed load create a pressure spike? I guess I'll sum it up by asking should a new reloader who's trying not to blow up himself or rifle be a little more weary when dealing with compressed loads? Thanks for the help
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The amount of powder filling a case does not compute to a dangerous load. Slow burn rates and small cases tend to = compressed loads.
When you first start loading it may seem odd to feel that "cruuunch" of a bullet in a compressed load, but it isn't dangerous when using the correct components.
Travis
Trump being classless,tasteless and clueless as usual. Sorry, trump is a no tax payin pile of shiit. My young wife decided to play the field and had moved several dudes into my house
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About the only thing to watch out for on listed compressed loads is seating depth. Sometimes the bullets will creep if compressed hard and other times the die will damage the bullet and cause inconsistent depths. I prefer to use a powder that fills the case, but doesn't compress myself. That said, I've had some rigs that really like certain loads that were compressed.
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Campfire 'Bwana
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Is a compressed load more prone to greater pressure spikes as the load is slightly increased? No. Could seating the bullet slightly deeper with a compressed load create a pressure spike? No. Compressing powder does not in itself increase pressure.
Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.
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Let me know if the quoted text below makes sense To illustrate the effects of variations in bullet travel before the bullet enters the rifling, we'll compare a standard load with adjustments made only in the bullet's seating depth.
In a "normal" load with the bullet seated to allow about one 32nd of an inch gap between the bullet and the initial contact with the rifling, pressure builds very smoothly and steadily even as the bullet takes the rifling. Pressure remains safe throughout the powder burning period, and the velocity obtained - 3500 fps - is "normal" for this load in this rifle.
Seating the bullet deeper to allow more travel before it takes the rifling, as in these next two illustrations, permits the bullet to get a good running start. Powder gases quickly have more room in which to expand without resistance, and their pressure thus never reaches the "normal" level. Nor does the velocity; with the same powder charge it only comes to 3400 fps.
Bullet seated to touch the rifling -
When the bullet is seated to touch the rifling, as in the accompanying illustrations, it does not move when the pressure is low; and not having a good run at the rifling as did the other bullets, it takes greatly increased pressure to force it into the rifling. As the rapidly expanding gases now find less room than they should have at this time in their burning, the pressure rise under these conditions is both rapid and excessive. Velocity is high at 3650 fps - but at the expense of rather dangerous pressure. Many rifles deliver their best groups when bullets are seated just touching the rifling. Seating bullets thus can be done quite safely if the reloader will reduce his charge by a few grains. The lighter load will still produce the "normal" velocity without excessive pressure. Sierra Bulletsmith's, Hodgdon's Techs, the guys at Hornady (quoted text above), and Mr Fred Berger all gave me similar answers to a question just like yours. Nosler and Speer kind of danced around the answer and in the end never game me a definitive enough answer. You may want to give Sierra, Berger, or Hornady a call for yourself. I personally do not own a strain gauge. What I can say is that while playing with the seating depth (.003, .030, .050, etc) at some point I obtain a tighter group. It just makes sense that the pressure developed would not remain constant when adjusting the over all length. Will the pressure change? Yes Will the cartridge obtain "excessive" or "dangerous" pressures but adjusting the OAL? It could
Remember, not everyone has a happy ending, so be happy when you can
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Thanks for the responses guys. Very good info. The crunch I had when recently working up some 308 loads with Varget is what had me concerned. I was under max load and saw no pressure signs but it just made me wonder.
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Measure the loads right now, then measure them again before you shoot them to make sure the powder isn't so compressed that it's pushing the bullets back out, changing your O.A.L., that could create a dangerous situation.
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Compressing powder normally causes no problems. In general, I haven't ever had a load that had to be highly compressed, normally if the powder is correct for the cartridge, it will at most be mildly compressed. I think with some that are a little short on capacity (.458WM comes to mind) it can be a problem, but not all that common.
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Compressing a load until it causes the bullet to creep is over-compressed IMO. If you are loading within the book limits and are concerned with bullet creep, you can always crimp the bullets in place.
Mildly compressed loads using stick powder are seldom a problem; compressing a load using ball powder is to be avoided. With the pletora of powders we have available now, one can usually find another powder that does as well w/o compressing.
Aim for the exit hole.
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Mildly compressed loads using stick powder are seldom a problem; compressing a load using ball powder is to be avoided.
That is an excellent rule of thumb.
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Mildly compressed loads using stick powder are seldom a problem; compressing a load using ball powder is to be avoided.
That is an excellent rule of thumb. Why?
Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.
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Will the pressure change? Yes
Will the cartridge obtain "excessive" or "dangerous" pressures but adjusting the OAL? It could Yes, but the "excessive" or "dangerous" pressures would occur with an increase in OAL not a decrease. The shorter the OAL the less the pressure, the longer the OAL the higher the pressure.
Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.
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Ball powders might clump up a little.....Phhhhtttttttt. Clear the bore.
That, and being double-based might give you some pressure problems.
Stick powders tend to have more air space.
I have noticed though, the stick powders will get into higher pressure quick when you run a 100+ percent. I really don't like to go much past 105%.
Anyway, that's my experience.
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Will the pressure change? Yes
Will the cartridge obtain "excessive" or "dangerous" pressures but adjusting the OAL? It could Yes, but the "excessive" or "dangerous" pressures would occur with an increase in OAL not a decrease. The shorter the OAL the less the pressure, the longer the OAL the higher the pressure. And that's dependent on the throating. If you seat into the rifling, yes. Anytime the cartridge has more capacity, you lower pressure, all else being equal.
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Stick powder has a lot of air space between the sticks (imagine dropping a box of tooth picks into a glass; the ball powder not so much, imagine dropping a hand full of BBs into the same glass.
So when you start trying to compress ball powder, you run the risk of bulging the case walls so's the round won't even chamber. And when the case tries to retract to it's original shape, you can get bullet creep.
Aim for the exit hole.
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OK, so it's external dimension/chambering issue and not a pressure issue. Got it.
I load my 9.3x62 with Mule Deer's 65gr of Ramshot BigGame and 286gr Partition with excellent results. This is a highly compressed load of ball powder, but obviously not enough to bulge the case.
Thanks
Last edited by steve4102; 09/29/12.
Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.
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Will the pressure change? Yes
Will the cartridge obtain "excessive" or "dangerous" pressures but adjusting the OAL? It could Yes, but the "excessive" or "dangerous" pressures would occur with an increase in OAL not a decrease. The shorter the OAL the less the pressure, the longer the OAL the higher the pressure. And that's dependent on the throating. If you seat into the rifling, yes. Anytime the cartridge has more capacity, you lower pressure, all else being equal. But things cannot be equal. The deeper the bullet is seated the farther from the lands the less the pressure. ![[Linked Image]](http://i2.photobucket.com/albums/y17/steve4102/pressuregraph.jpg) ![[Linked Image]](http://i2.photobucket.com/albums/y17/steve4102/seatingdepthvpressure.jpg)
Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.
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And that's dependent on the throating. If you seat into the rifling, yes. The top chart show seating into the rifling, creating higher pressure. Seating back from there obviously will decrease pressure. I've seen indications that seating deep into the case would have a pressure increasing effect, also. This has just been my experience. I've not deliberately duplicated the example you've shown, but it might be interesting to do so, especially with other powders, something I would like to do before I stated emphatically that a certain action has a certain reaction. It looks to be true for that load and rifle, but I am curious about other combinations and if the trend would continue. In regards to the second chart, I've never seated at .250+" off the lands, instead trying to keep jump within .030" of so, the closer the better. That's how I've experienced, in most cases, the best accuracy. Occasionally, I've run across rifles that would shoot well with a long jump to the rifling, finding this out either by experimentation out of frustration with the accuracy of that individual rifle, or simply mag box constraints. In the second example, I just give the cartridge enough room to reliably function through the mag and fire away. And it may or may not be with a compressed load...
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Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.
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That's an interesting thread with a lot of information. I'll have to thank you for pointing that one out.
I will certainly follow the procedure outlined in post #5475810, and see if my results are the same.
Thanks again.
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