45colt blow back

Seabass

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I am getting some nasty blow back in my marlin 1984 cowboy in 45colt. My load is a mild one for CAS

8gr unique
200gr cast swc
win brass
WLP primers

I get around 1150fps out of the 20in barrel and it is accuacte in my rifle and Ruger Vaquaeros.. The blow back didn't happen with CAS factory loads so any idea what I'm doing wrong or how I can reduce the blow back. I have to wear glasses each time I fire the rifle.

Thanks

Seabass
 
I get a bad shot in the eye of gas/powder residue when I shoot the darn thing... yes. It like somone blowing in your eye really hard and I have to put the gun down and let my eye water for a couple seconds... It sucks let me tell you. The load is accurate and low recoiling (better for CAS) so I don't want to play with it too much.. I suppose I could up it a little but the weak facotry ammo didn't do this?? weird..
 
"I have to wear glasses each time I fire the rifle".


http://www.canadiangunnutz.com/forum/showthread.php?t=298662

You should be wearing eye protection all the time anyway. I suppose if you put more powder in the gun it will then be louder and you may have to wear ear protection too.

By the way, I'm loading almost exactly the same load for the same gun, 7.5 gr of Unique vs your 8.0 gr and I'm not experiencing any blowback issues.
 
Switch to Trail boss powder, It builds pressure quickly to seal the case mouth but keeps velocties low good for cowboy loads.
Super clean burning as well, try around 6 grains for a 200 SWC.
 
Seabass if your Marlin is anything like mine the chamber is about 4 thousands over size, and the bore is .454. When I was shooting hard cast bullets I got a bit of blow back like you. My first load was 7.5 gr of 231 with a 200gr hard cast semi wad cutter for a bullet. One of the things you can do to stop the blow back is go to a softer cast bullet. Since I switched to a softer cast round nose bullet with 5.5 gr of Trail Boss the blow back is gone. I don't know this for sure but in all likelyhood the bullet in the factory loads is a softer lead. That lets the bullet size up to fit the bore tightly, raises the chamber pressure and seals everything up. Try slugging your bore and if it is oversize a softer bullet may just be your answer.
Chuck
 
There's little doub't that the cartridge case is not sealing the chamber. To get a seal, you need to up the pressure.
You could up the powder, or use a heavier bullet, or switch to a faster powder.
I'm betting a full load of BP seals the case well.
 
one thing that helped for me was to have a good crimp , and to have bullets .452 , the smaller ones also started leading, and yes to john y the full case of black seals good (and I like the NOISE) , I have used geen dot with good sucess as well , I thought it burnt cleaner than unique.
 
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