Been around the forum awhile and finally came up with a question I couldn't answer with a search.
I've just started using dacron and have had excellent results. My fired cases do have some burnt (melted?) residue on the exterior of the neck. It comes right off with a little 0000 steel wool, but I'm not sure if this is indicative of a problem or not. The chamber neck/throat stays clean, but everything I've read here suggests that it generally gets blown out the barrel, and if recovered, looks like new.
Thank you for your time, Nick

Been there and figured there was also melted plastic in the barrel. Does it do any harm??? Have no idea. If I remember correctly there was also burning stuff come out of the rifle and fall in the brush.

Haven't seen anything being left in the barrel after the shot.
I'm only using 2grs atop 94grs varget in a 470 Mbogo case. A 500gr a-frame does 2200fps in my 20" barrel. The varget fills about 85% with the bullet seated.
From what I've gathered from others here, I'm doing it right -just weird I've never heard of neck deposits in the 2000 posts about dacron.
Thank you, Nick

you probably don't need the dacron with that load.
fillers are used with medium speed powders [which varget certainly is]
to keep the powder against the primer to help ignition and keep extreme spreads in velocity smaller.
generally a load in the 60% case cap, and smaller range are most benefited.
you may benefit from case annealing to help it seal better.

quote:

A 500gr a-frame does 2200fps in my 20" barrel. The varget fills about 85% with the bullet seated.

If I had an 85% capacity load I sure wouldn't be jacking around with a filler.

In smaller cases I've had no reservations about an 85% load and they've all shot well with no "click... bang"s. But being new to loading large cases (bigger than 375 h&h), I wasn't sure.
My reason for using a filler was that 15% in a case this size is quite a bit of space. Powder is about 5/16-3/8" below bullet base.
Anybody currently loading big cases with dacron seen what I'm talking about?
Thanks for the replies, Nick

Did a little experimenting today, tried the load w/out filler. Extreme spreads went from 20ish to 80ish fps. Also noticed though that I had a lot less crap on the case necks. Previously, I had always shot a couple rounds loaded with trail boss right off the bat. Today I went staight to the heavier loads. So it appears that the trail boss was leaving a lot of grunge in the neck area that would show up when I fired warmer loads. Thanks all for the feedback! -Nick

I, too, am thinking you don't need the filler in that load.

Yes, Trail Boss is known for being dirty--leaving lots of residue--because of its high bulk.