Using fiberglass insulation as "filler"?

[Cayoot]

I'm hoping to tap into the Brain Trust here at Cast Boolits for an issue I'm having.

I have a .30 calber mould that Buckshot applied his artwork in hollow pointing to.

He did a beautiful job, and I also have a copy of the article "Hollow Points in the .30-30".

I loade up using the recommended 24.5 grains of IMR 3031 powder and steped out back to my 100 yard range.

The measured velocity produced by the first (and only) 5 rounds ranged from 1,848 fps down to 1,560 fps. Also, the shot group had a 7 1/2 inch verticle string (although the horizontal variance was very small).

So I'm thinking that my problems might be caused by the large amount of excess case capacity in these .30-30 cases.

I'm thinking that I probably need to use some sort of "filler" to keep the powder in a constant position (in relation to the primer).

I think Kaypok is the most common filler material used, but I don't have any of that.

What I do have alot of is common household fibreglass insulation. (Because I just added an addition a couple years ago and bought more insulation than I needed).

What is the general opinion about using this "Owens-Corning" solution? Is it as safe to use as Kaypok?

Does anybody have suggestions on some other material?

I've heard of using cream of wheat in straight wall cartridges, but I don't know if that would be safe to use in a bottle neck cartridge due to (what I've heard is) it's tendency to form a firm "plug" that scrubs the bore as it is pushed down the barrel. I'm thinking that it might build up pressures to a dangerous level while it is being forced through the constricted throat of a bottle neck cartridge.

Of course, like most things in life, I don't really know what I'm talking about here.

So please provide some guidence.

Thank you in advance!

[KCSO]

Why not just use sand? I won't let a customer use a fibreglass ram rod as they are the most abrassive thing you can stick down the barrel.

[montana_charlie]

If you were insulating your house, you already know about that gritty stuff that gets in your lungs and makes your skin itch. I wouldn't want that crud in a rifle of mine...nor spewing out of the muzzle to get in my eyes.
CM

[Cayoot]

Ok, but I find it hard to believe that fiberglass is harder than the barrel steel. But if fiberglass is not a good thing to use, thanks for letting me know. Do you guys have any other ideas?

Anybody know of a good source for kapok?

[leadeye]

Those glass fibers are pretty hard and sharp. That's why insulation rubs your skin raw. I would stay away from it.

[fourarmed]

Glass will scratch steel, not the other way around. Use dacron quilt batting. About a half grain will do it.

[Cayoot]

Ok I'm convinced...no fiberglass.

What about my basic premise? Do you guys think I might be mistaken about the cause of my variances being the excess case capacity?

[Cayoot]

Thank you forarmed! That was exactly what I was waiting to hear! I've never thought of dacron!

I'm going to the fabric store today!

[Lead pot]

Use a powder that fills the case.

LP

[runfiverun]

a filler will definately help with your vel variations.
i use the dacron and plain old dryer lint.
the dryer lint will be like adding another grain or so of powder.
i also try and use the same type of lint all the time like from the towells or just the levi's.

[Boerrancher]

If you you are shooting between a 150 and 170 gr boolit use 30 grs of IMR4064. I shoot 30 gr of IMR 4064 in my Mod 94 30-30, behind both the 150 and 170 gr gas check boolit. It is a bit hot with the 170gr, but it shoots well, and is just right with the 150 gr and shoots great.

Best wishes form the Boer Ranch,

Joe

[Cayoot]

If you you are shooting between a 150 and 170 gr boolit use 30 grs of IMR4064. I shoot 30 gr of IMR 4064 in my Mod 94 30-30, behind both the 150 and 170 gr gas check boolit. It is a bit hot with the 170gr, but it shoots well, and is just right with the 150 gr and shoots great.

Best wishes form the Boer Ranch,

Joe


Thanks Joe, is the 4064 powder bulky enough to fill the cartridge case or do you utilize a filler?

[Cayoot]

a filler will definately help with your vel variations.
i use the dacron and plain old dryer lint.
the dryer lint will be like adding another grain or so of powder.
i also try and use the same type of lint all the time like from the towells or just the levi's.

DRYER LINT!!! What an excellent idea! Thanks!:drinks:

[Bret4207]

I used insulation a couple times. I know now I am unclean, sahib.....

[testhop]

i have kapoc and will send you some pm me with where to send to
it came out of old lifejackets the coastguard scraps them off all ships if the cloth tearswhen pulled on kopacjackets have have not been used for years

[jhalcott]

Dacron is a decent filler in bottle neck cases. You are better off NOT using any filler IF you can find a powder that fills the case or is not position sensitive. Since you hollow pointed the mold my guess is that you plan to hunt with these bullets. You also forgot to mention just what mold you have! Any way IMR 3031 can be loaded to 27 grains and gives about 2000fps with a 170 grain cast bullet. WW 748 can be run up to 35 grains and is a compressed charge. It's velocity is near 2300 fps. Are you using a "reccommended" load for the unmodified mold? This could mean you are shooting a bullet several grains LIGHTER than the reccommended weight. All you MIGHT need is a change in powder charge.!

[montana_charlie]

I'm thinking that I probably need to use some sort of "filler" to keep the powder in a constant position (in relation to the primer).
While developing a smokeless load for a modern rifle, I am a lot pickier when shooting it...than when out hunting with a known good load.
So, every shot from the bench starts with the muzzle pointed to the sky to settle the powder to the back of the case.
Then I lay the forearm on the rest with no jostling, and fire the round.

The powder may not be in the 'most optimum' place in the case...but it is always in the 'same' place. That removes the variation which seems to be troubling you.

The only time I ever look for a filler is when I take two baked potatoes...because the steak looks kinda puny.

CM

[1Shirt]

My pet load for my Mod 94 Carb. is one of Buckshot's masterpiece HP's in 31140, over 16 gr. of 2400, sized .310, and it chrono's right in the 1750 fps bracket. No filler needed, but you of course need to be careful of a double charge. I weigh all finished loads where I use fast burning pistol or shotgun powders to be sure that I have not doubled. When I do use a filler with some of the slower burning pdrs, I use about a grain of dacron. For a number of years I used a quarter sheet of single ply toilet paper on 7mm to 30 cals, and went up or down progressivly on smaller or much larger cased. Nope, no fiber glass!
1Shirt!:coffee:

[KCSO]

I was pressed for time when I first posted so i will ask forbearance if i was a little curt. I have seen a new barrel ruined in one summers shooting by the use of a fibreglass ramrod. if that rod contacts the bore at all it wears it away like fine sandpaper. Fibre GLASS= Galss made from SAND. Now as to a proper filler everyone has put forth good ideas. My personal favorite is Cream of Wheat, and if you get lost in the woods you always have breakfast. I will also recommend that if this is a low (Under 30,000) load you try a PISTOL primer. I have no sientific reason but for me a pistol primer with Red Dot or Unique or even sometimes 4198 will lessen the stringing. By using CM's methods on the bench and using pistol primers I very rarely have to resort to a filler.

[Red River Rick]

Does anybody have suggestions on some other material?



If your trying for an "All Natural" product, "Belly Button Lint" would be best. Besides, there's probably enough member's here that could send you an endless supply, most likely free, as well.

Cayoot, just :kidding:

RRR

[eka]

Dacron here too. You can get it in a bag or in sheets. I use the bag. Use a small tuft and push it into the case with a small screwdriver or the like. Make sure the dacron goes all the way to the powder. Leave some sticking out of the top of the case. The boolit will push the rest inside the case. You definitely don't want to leave any air space. You also don't want to make a wad. Either one of these things could result in a ringed chamber. Careful with near max. charges as any filler will increase pressure some. When using powders like Red Dot, Unique, and 2400 in large cases, I usually try it both with and without the dacron. Some loads show a marked improvement and some it doesn't seem to make any difference. I usually use between a half grain and a grain. Just follow these precautions and go at it. I think you will like it and find it useful in some circumstances. With the sheets, you can cut small squares and then fluff them up. I've heard that is faster and I can see how it would be. I bought the bag when I started with it and it looks like it's going to be a lifetime supply :-D.

Keith

[Kraschenbirn]

Grits. They're cheap, they don't cake up like Cream of Wheat, and...if they don't work as a filler...you can always cook 'em for breakfast.

Bill

[GOPHER SLAYER]

If you must use fillers why not use cotton balls? It burns cleanly and doesn't harm the barrel and you can buy a large bag at the drug store for very little money. I was told by a friend that he used a Synthetic and it melted in the barrel. I don't know if it was dacron or not. I don't use fillers anymore after reading reports in Black Powder Cartrige MAG. about ringing the chambers of guns where fillers were used. I read the article at 10pm and I had to check one of my 45/70s.Sure enough there were tiny rings at the forward end of the chamber. My load for that rifle was 15 gr. of unique with cotton filler to hold powder against primer. One more thing. By using cotton you would be Going Green and not harming the planet. BARF,BARF

[kir_kenix]

I have a friend who has used pink insulation as a filler for years and years. I'm not saying its a good practice, but hes been doing it for longer then I've been alive, and he shoots thousands and thousands of rounds a year thru his rifles, and they group better then me most days.

Anyway, I'd say that dryer lint is just as effective as anything else, and its certainly cheaper. Give several a try before you settle on one. I once tried packing peanuts, but did not have good results. Recently however, bullshop mentioned that hes been using them with good results, so I'm going to go back and give them a try again.

[longhorn]

I've tried fiberglass insulation, didn't like handling it, sure don't like its flammability--could that lead to some melting in the bore? Tried cotton, seemed too heavy, more likely to compress over time with handling. Tried toilet paper, bothersome to handle with my clumsy fingers, hard to arrange consistently in the case. Dacron works for me for literally thousands of rounds-and a single Dacron filled pillow from the local mart may well be a lifetime supply. As for rings, use the filler correctly--as filler, not wad No wad plus no pressure wave equals no ringed chamber, at least in my guns. All this for straight walled cases; as for bottlenecks, I use it in a .375 H&H, but never again in a .30-30 or 7x57--didn't like the looks of the primers.

[Glen]

A few thoughts for this thread --

1) I don't think that the load under discussion (24.5 grains of 3031 in a .30-30 case) needs a filler for uniformity. 3031 is very easy to light.

2) What kind if crimp was used? Sometimes a non-uniform crimp can lead to this sort of velocity variation and vertical stringing.

3) What primer was used? Vertical stringing is commonly due to ignition variations and it's the primer that's responsible for ignition after all.

4) What size were the bullets? What size is the throat? If the bullets are undersized relative to the throat you can get blow-by prior to engraving and that can lead to ignition variations.

5) As for using fiberglass insulation as a filler, I can think of no better recipe for giving oneself silicosis. Think about it, you're taking fragile glass fibers and blasting them violently out under high pressure out of a gun barrel at high velocity as a finely divided aerosol. This cloud is being ejected right in front of the shooters face, where it will be easily inhaled. These fine glass fragments are exactly the sort of thing that cause silicosis. Oh yeah, they will also scratch the bore of the rifle while in transit, but I consider that to be secondary to what they will do to the shooters lungs. Oh, by the way, glass fibers are not flammable.

6) There are a number of well-established fillers that have proven useful over the years. These include finely granulated cereals (like Cream of Wheat, or Malt-o-meal), cellulosic materials (like toilet paper), natural polymers (like Kapok), synthetic polymers (like shredded polyethylene, aka "Super-Grex", or Dacron pillow stuffing). Personally, I am not a big fan of fillers, simply because I don't care for the added step of having to add them. I would rather just choose a powder and a load that doesn't need a filler, but to each their own.

In conclusion, I would say this -- size the bullet to be a snug fit in the throat of your rifle, apply a good crimp as uniformly as possible, forget about using fiberglass insulation as a filler, and if you do decide to use a filler then use cream of wheat, shredded polyethylene or dacron, or somesuch.

[Blammer]

so just how much space is left in the case?

I find it hard to believe that filler is the only answer.

I'd try a few more or a few less grains of powder and see what happens to accuracy.

[jimkim]

I think Glen is right. I would try a heavier crimp. Then a different primer.