Paper patch/breech seated loading

Discussions of powders, bullets and loading information.

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bruce m
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Joined: Tue Aug 04, 2009 5:25 am
Location: australia

Re: Paper patch/breech seated loading

Post by bruce m »

with fixed ammo, a main tuning method is to adjust charge/compression for a given seating depth.
with breech seating you fill the case as full as possible, and only tune by adjusting the airgap between the wad and the bullet.
compression for tuning is irrelevant in this situation.
the odg carefully droptubed the powder and no more, then seated a wad, sometimes even just paper.
you need to be careful doing this, as powder packing must be even to get consistent grouping.
if the charge level varies much in a case from the others, do not use that case.
luckily our cases are fairly consistent today.
camming in groove diameter bullets in fixed ammo is fraught with danger accuracy wise.
you need good neck tension and firmly compressed powder as well to resist bullets pushing back in the case and further compressing powder.
you just have to play with these things and find a nice balance.
bruce.
ventum est amicus meus
Kurt
Posts: 8428
Joined: Wed Oct 12, 2005 10:28 pm
Location: Not Far enough NW in Illinois

Re: Paper patch/breech seated loading

Post by Kurt »

Bruce,
I see a drop off with accuracy chambering PP bullets .001" over bore diameter with a firm thumb pressure seating in a case of low compressed powder in the case. This has not been an issue when I was still using the Goex Exp or the KIK powder I used to compress a bunch more than the Swiss and OE powder I use now.
Now I have to run my patched bullets through a push through die so they are right at bore diameter or a halve under.

As far as the air gap breach seating.
I tried this and it always made me curl up my toes because I rung a chamber once so I don't do this. I tune my loads by adding a wad or two and changing the compression but the final wad is flush with the case mouth held with a slight roll crimp holding the wad and the wad makes contact with the bullet base. I use a slight roll crimp because I start seeing mouse nibble gas cuts on the bullet base with a taper crimp holding the wad. I think the wad gets reduced in diameter with the taper crimp and with the bullet base in the throat it does not obturate fast enough sealing the bore like it would with it seated in the case of fixed ammo. But with a roll crimp the brass needs to be uniform in length. A crimp too tight on a .060 polly will spike a vertical.
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semtav
Posts: 2880
Joined: Wed Feb 03, 2010 3:21 pm
Location: Montana

Re: Paper patch/breech seated loading

Post by semtav »

bruce m wrote: Thu Nov 28, 2019 2:32 pm semtav,

incidentally, my 45/2.4" loads take just on 100 gns powder.
bruce.
Sounds right. Just figured out I was putting 90 gr not 80 to fill my 40-82 cases. Pretty sure its not going to comprrss that load any more :oops:
semtav
Posts: 2880
Joined: Wed Feb 03, 2010 3:21 pm
Location: Montana

Re: Paper patch/breech seated loading

Post by semtav »

semtav wrote: Thu Nov 28, 2019 7:25 pm Bruce my initial reply was in response to Brett's comment
Someday ill learn to type your name properly. Or disable my auto correct ?! :oops:
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