Position sensitive test.

[JeffinNZ]

Team.

I have been testing Freechex II .22 gas checks lately and my .223 Rem 700 started playing up on me. I thought the wider than usual groups could be either tension related or powder position; I shoot a 225462 over 6gr of Green Dot.

In preparation for the next batch of tests I annealed all the brass then load 5 rounds per usual and the next 5 rounds with a very small wool wad to keep the powder at the bottom of the case.

Here is the results. First shot of the day went high. 10th shot went low (gutted about that given the group). Pretty much shows the Green Dot in the .223 is position sensitive.

http://img.photobucket.com/albums/v505/JeffinNZ/Shooting%20stuff/DSCN0987.jpg

[windrider919]

I thought wool as a filler was not recommended due to potential chamber 'ringing' effects? I use Dacron fiber puffs because the fibers are totally consumed in firing.

[303Guy]

Wool wads - that's what I was supposed to get! (Forgot).

So, how would wool differ from dacron? (I know that cotton comes out whole - if it doesn't burn!)

Thanks for the info, JeffinNZ

[JeffinNZ]

Six of one and 1/2 a dozen of the other on the dacron/wool thing. The wool burns up on the way down the barrel also. I have fired literally THOUSANDS of rounds with a wool type wad/tuft and never had a problem. Still, I don't burn really fast powder in my larger cases. Fastest I burn in my .303's is H4227.

[Whitespider]

I've found that all powders (or at least all the ones I've used) are position sensitive; a chronograph will tell the story. I usually test by pointing the muzzle down to settle the powder as far away from the primer as possible before each shot, then muzzle up, compare the chronograph results. The difference can be sometimes very dramatic; I've seen as much as 600 fps difference with about 100-200 fps being the norm, even with load densities over 90% I get measurable differences in statistics. And when you start swapping primers during those tests a fella' learns, real quick, that all powders are also primer sensitive.

[Mallard57]

I thought wool as a filler was not recommended due to potential chamber 'ringing' effects? I use Dacron fiber puffs because the fibers are totally consumed in firing.

I believe there is a bunch of debate about fillers in general, Dacron puffs included.
My experience with fillers is very limited, I can see them being a wonderful thing and if misused a potential for ruining a firearm.
Jeff

[303Guy]

Are some powders more sensitive with some primers? i.e. a more powerful primer might lessen or increase the effect?

I want to use a filler that fills that last 5% of case space. I want it there to act as a wad behind my CB's. I have found there is a difference in that department.
I just never got to buying the right stuff so I used cotton. I had been warned about starting grass fires so I only used it for test tube firing. Most of the time, cotton does not burn. It does not even scorch or singe. But it did once! It actually scourched the catch cloth! So, better safe than sorry.
It's a pity though because it scrubs the bore!

[skeet1]

I was reading another forum and Ed Harris stated that he uses Winchester primers because they have aluminum in their priming compound that helps with powder position sensitivity. Have any of you heard of that before?

Skeet1

[felix]

Whitespider is correct on every front, so it does not make much difference in the primer composition as a result. Getting the most consistent ignition is the ONLY criteria and that by any means necessary for the load on hand. ... felix

[windrider919]

According to a fellow who I used to know who worked for Speer doing load development 20 years ago, if the open space is 20% or less of case volume it does NOT need a filler, ever. IE: if you have 5% space, forget about it. The major ammunition manufacturers do try to build their loads by selecting a powder that, along with giving the velocity they want, fills the case almost completely because that usually gives better accuracy.

However, if making reduced loads with fast powders, usually pistol powders where the powder might occupy 10% of case volume some type of filler might [really should be] be needed. Back then there was a lot of damaged rifles with chamber ringing shooting reduced loads. The theory was that a pressure wave was generated that bounced back and forth in the case and that either the pressure waves overlapped and bulged out a ring. Or that the pressure wave caused the progressive burn of the powder to dramatically increase, creating a pressure spike going over max pressure. Or that the powder charge was fired / shot from the rear of the case to slam up against the bullet base and then pressure spiking and causing a bulge at where the bullet base had been. Honestly, I never learned what was determined as which one was true. But I did learn that Dacron was a good filler if the case was at least 50% full to keep the powder back in the base of the cartridge where it burned better. In this case chamber ringing was not probable. I also was taught that the charge of 50% or less needed a filler to both keep the powder in the case bottom AND to prevent pressure spikes / chamber ringing. Dacron does not work here because it is fluffy, and something more solid was needed to fill the space. Cream of Wheat (COW) or grits or sawdust (and all sorts of other fillers) have all been used but there have been a few cases of caking and higher pressures with them. I use flake PE (polyethylene) filler just like the 'buffer' in shotgun shells because it will not absorb moisture and it weighs out consistently. And it is lighter than COW by volume.

NOTE: If using a 'solid' filler you must add its weight to the projectile weight and check if the total mass requires a powder reduction. Filler can add 30 to 50 grains of additional weight to the basic bullet weight. This can drive a reduced charge into a possible max charge.

My solution was to stop using fast burning powders in large capacity cases. There is always a medium powder that fills enough of the case and yet still gives consistent low velocity that works. It was nice to think that the fast powder light charge was economical but not at the cost of damaging my firearms.

[cajun shooter]

Well, I know why Jeff uses the wool filler instead of dacron. I don't think there are too many dacron producing sheep in NZ unless they imported Dacronners to shear.

[runfiverun]

skeet ed harris does recommend winchesters for just that reason.
maybe this discussion is why i like to use medium powders [4895,3031, 2230] with fillers and the most consistent vel variation producing primer i have be it lr/lp fed win whatever.
or slower powders that fill the case.

[JeffinNZ]

Well, I know why Jeff uses the wool filler instead of dacron. I don't think there are too many dacron producing sheep in NZ unless they imported Dacronners to shear.

:-D:-D:drinks: