Stuck primers - explain to me what is happening

[RobRed]

Was at the range today shooting my Accura MRX and had an interesting observation.

100 grains of tripple 7 - Primers kept expanding and getting stuck in the breach. Had to pull them out with my leatherman

100 grains of white hot pellets - clean primer, no blow by what so ever, primer came out as normal. This made me say hmmm.

Dropped the triple 7 - down to 90 grains and had the same result at the white hot pellets. Basically zero blow by and no stuck primers.

I was shooting cheddites which I know are on the short side. What what actually causing this with the stouter charge? Is this a head space issue? Would using o rings fix this? Looking to understand the “why” behind this.

Also it’s interesting the triple 7 seems to have a bit more power than the white hots.

Another interesting observation, up until this point I’ve been shooting all powder and even pellets with the BP 209 breech plug. I didn’t think this was an issue until I switched to the conventional breech plug (wasn’t shooting BP209) all of a sudden my groups were way more consistent and much tighter. Can anyone explain why this may be? Was the BP 209 breech plug causing the primer to blow the charge forward?

 

[deermanok]

Sounds like you found the answer to at least part of the issue.
I know that the BH breech plug has that small reccess area to allow the Blackhorn to get closer to the flash of the primer for better ignition.

 

[bronko220002]

How long and/or how many shot were done with the BH209 BP? Did you clean the flash hole and primer recess? Is your flash hole larger than .035"? Do you have any rubber O-rings to put under your primer?

 

[ElDiablo]

To answer your first question, the primers are expanding slightly due to pressure. Those Cheddites are larger od so they don’t have to expand much to stick in your plug. You could try a different brand 209 (US not an Euro brand) and probably see different results.

 

[rangerod]

I'd try Federals it you can find some.

 

[jd24.5.48]

The original breech plug can be used with pellets and any loose powder except for blackhorn powder. I have never used the original breech plug in my accura V2 lr so I don't know what difference it would have. I'm using the blackhorn breech plug with Winchester W209 primers and haven't had any problems with sticking primers or blow bye. I tried some cci 209M primers and they have a good bit of blowback! I believe it's SKS firearms that sells a new blackhorn breech plug for less than $30! It's supposed to be a good plug and I'm going to try it.

 

[jd24.5.48]

It's SSK that sells the breech plug.

 

[jd24.5.48]

The breech plug also has a replaceable vent liner already installed. It's $26. It's cheaper than a plug from CVA!

 

[Travis299]

Fired & unfired primer from my Accura V2 using the rubber O-Ring in the primer pocket shooting 2 pellets of T7.