Can we discuss the use of Dacron ?

yodogsandman

Well-Known Member
I've shot thousands and thousands of rounds using dacron in my 7.62X51 (308) Mauser. It helped to prevent stringing using 28.0 gr AA2230 and the 195 gr RCBS 30-180 SP. BUT.....

I had Dacron build up in my chamber, just at the end of the case mouth in my 6.5 Swede . It was black hard plastic melted into it. It caused a situation where I got erratic ignition/high pressure using Reloader 19 and discontinued shooting the remaining rounds in the lot. The last shot I took, I believe, caused the case mouth to hold the bullet, almost preventing it's release. The bolt lifted hard and had a heavy scrape on the base of the case. That's when I found the blackened, melted deposit on the case mouth. I scrubbed the chamber with a bore brush and used a pick to completely remove the crud at the end of the case mouth in the chamber. I haven't used Dacron batting since (for over a year).

This is the first time I've mentioning it to anyone. I was afraid I did something wrong. After much consternation, I just know it wasn't me, done it thousands of times before. I fluffed the 1/2 gr square of Dacron batting up and using a wooden match stick (sans the tip), pushed it into the case mouth, little by little, with it showing half way up the neck. Maybe it shouldn't be used in the smaller necked cartridges. Proceed with caution using Dacron, my friends.
 

Ian

Notorious member
I guess I never had that problem in my Swedes because I make brass out of '06 and .270 cases with necks long enough to completely fill the chamber. Compacting buffer can do some scary stuff inside cartridge case shoulders, too. Main thing is always pay attention, something may seem fine for a bit and then the big surprise happens.
 

KHornet

Well-Known Member
I see the word "packed" used here. Dac should never be "packed". If you pull it apart and fluff it and push it down to a level just barely below the neck it will occupy the area between the powder and the base of the bullet as it expands. When I say pulled apart and fluffed, it means you can see thru the fibers. Just my opinion.
 

Uber7mm

New Member
I see the word "packed" used here. Dac should never be "packed". If you pull it apart and fluff it and push it down to a level just barely below the neck it will occupy the area between the powder and the base of the bullet as it expands. When I say pulled apart and fluffed, it means you can see thru the fibers. Just my opinion.

Agreed: Fluff it out is the way to use Dacron. I pull the fibers apart as much as possible, and gently feed it into the case with a Allen key or like tool. It's just there to fill up the void in the case between powder and bullet.
 

fiver

Well-Known Member
yes definitely fluffed and placed between both the powder and the boolits base with some light compression.
 

Josh

Well-Known Member
Could my problem have been from having to seat the 140gr 6.5mm bullet deep into the case?
That is very possible, If the bullet is seated way below the neck it will be compressing the fluff into a tight ball. When using that combo I would try adding fluff to the base of that bullet or a hair above it. You only want minor compression.
 

fiver

Well-Known Member
I think Ian actually hit on the issue.
you have a gap right there [case mouth] where the Dacron is exiting the case mouth behind the boolit [under pressure] and it's just getting into the open space.
maybe getting slightly trapped outside the case mouth as it's opening or closing from the pressure.
 

Ian

Notorious member
If your bullet has a deep enough lube groove, is made from the right alloy, pushed with the right powder to do the job, obturates the throat immediately, and if the case neck obturates the chamber following the bullet base as the bullet moves out of the neck, lube will pump from the groove to the gap at the end of the case mouth and create a hydraulic bridge that protects and guides the following driving bands into the throat entrance.

You'll know if your load is creating a lube bridge or not by looking at the fired case mouth. If there is a little neck extension of clean lube all the way around the end of the case mouth, you know obturation of chamber by neck and throat by bullet upon firing happened, and also that lube pumped from the groove(s) into the gap between the case mouth and end of chamber.
 

Ian

Notorious member
One addition to above: You're more likely to see this lube bridge when using filler/buffer than not because the gas is less likely to blow around the bullet body and blow lube ahead of the bullet or around the case mouth and back on the outside of the case neck when there is something behind the bullet to maintain case neck obturation (obturation in definition, as in GAS SEAL) as the bullet moves out of the case.
 
9

9.3X62AL

Guest
The method I used is as described in Posts #25 and #26. Won't do it again. AT ALL.
 

sundog

Active Member
I gave up on dacron/kapok/toilet paper/etc a long time ago. I am quite satisfied with results I get, therefore it is a extra, unnecessary step for me. For those of you who find the practice to your advantage, all I can say is, "have at it." Btw, please do not try to convince me I was doing something wrong, you'll be wasting time better used for stuffing dacron. I'm pretty sure I may do some things others may think unnecessary, but that's just the way things are. Don't get me wrong, I'm not throwing a wet blanket on your party, just saying it's not for me.
 

Brad

Benevolent Overlord and site owner
Staff member
I generally don't use Dacron as I dislike the extra step. It just doesn't fit into my loading methodology.
Notice I said generally, there are times it just works better. I just try to avoid those situations.