View Full Version : Using Poly-Fil in light loads

August 16, 2010, 01:47 PM
Hey guys, I tried this thread over in the reloading and casting forums, but my turn out has been small. I was really hoping for more input from fellow reloaders, and being that it pertains to light loads, I figured the CAS guys would certainly have heard of this concept before. I came across some videos on youtube about using POLY-FIL (craft stuffing) in lightly charged cartridges. It makes sense that it holds the powder down at the flash hole in order to get a more consistent burn from one round to the next. I love the concept, but I have a few questions that maybe you guys have the answers to. How exactly would you determine the amount (in Grains) of Poly-Fil to use in any given cartridge? I would assume that it doesn't take much, but how much is too much? It does take up casing volume so it has to affect pressure to some degree, right? So, if it does affect pressures in the casing do I need to throw a lighter charge to accomodate for the extra space being taken up in case? I am not a competition shooter and my reloads to date are light loads for recreational plinking, but I do enjoy a good accurate round. It would seem that adding the Poly-Fil would increase accuaracy. I guess that I need to experiment and decide if I want to implement this into my normal routine. I've only been reloading for about a year now, so while this concept is new to me, perhaps some of you have some experience with this or something similar? Tell me what ya think guys! I put the links down here, you may have to cut and paste them, sorry. I shoot better than I run a computer


August 16, 2010, 02:01 PM
I don't know from my own experience but ...... I read a review of EH Harrison's NRA book Cast Bullets today. I googled the author/title to find it. The reviewer was reviewing many different titles on the topic.Here (http://www.surplusrifle.com/shooting/castbulletloaddata/index.asp)is the webpage, he said that the Harrison book had good info if you ignore the using of Dacron filler for reloading cast bullets. He said it was found to be unsafe. I hope someone with more knowledge on the topic comes along as he didn't elaborate. Just a heads up.

August 16, 2010, 02:17 PM
Well, there's this anecdotal evidence that says that a compressible filler (Dacron being one of them) can lead to chamber ringing. The theory goes that the Dacron can compress, leaving a void between it and the bullet. When the powder charge goes off, the Dacron strikes the base of the bullet and upsets it somewhat. A few times of that and the chamber gets a ring around the mouth of the case.

I'm not aware of anything approaching research and it's one of those subjects that seem to get some folks riled up. I don't use any fillers at all, so I can't comment one way or the other.

August 16, 2010, 04:47 PM
I tried it when I was loading hot 41 mags. The rounds with the fill had a slightly better velocity consistancy. this velocity advantage was in the neighbor hood of .5%. certainly not enough to warrant the expenditure or the extra time involved. I finished the test project and threw the excess poly-fil away.