Primer fit

[CarlV]

On a range day last weekend I reported that I experienced some hang-fires towards the end of the day using BH209 and Remington STS primers in my Remington Genisis.

The Genisis uses the rotating torch cam action to secure the primer into the breech plug. It doesn?t force the primer into the breech plug pocket like a bolt action might do, but simply keeps the primer from migrating backwards out of the primer pocket more than the clearance of the torch cam to the barrel. The seal is also the front of the primer in the bottom of the breech plug primer pocket.

In measuring the different primers I had on hand this is what I got. I must also report that it appears that primers are not all that uniform in length. These are the most uniform of the 5-primer lots I measured.

Remington STS Lot 837
.2945
.2935
.2938
.2942
.2948
Average of .2942


Federal 209A
Lot 4W610
.2952
.2951
.2950
.2960
.2958
Average: .2954


CCIM Lot AX265
.2970
.2990
.2980
.2980
.2980
Average: .2980


Winchester W209 Lot BLL398
.3010
.3010
.2990
.3020
.3010
Average: .3008

Winchester 777 Lot BML059
.3000
.2980
.3010
.3000
.3000
Average: .2998


Then I decided to try to verify how they fit in the breech plug of the Genisis with a feeler gauge with the torch cam closed. This didn?t work very well since the breech block to barrel clearance is between .006 and .007 (.006 feeler gauge would slip between the breech block and the barrel where the .007 feeler gauge wouldn?t). I believe the SAMMI headspace maximum spec is .006? for most cartridges, so any of the primers should fit good enough to give proper ignition of the primer. I don't believe I got accurate measurements so I won't post them.

In retrospect, I believe that the hang-fires I experienced the last range day were directly my fault by not realizing the fire channel in the breech plug was becoming severely carboned up and keeping it cleaned out every ?so many? shots with a 1/8 inch drill bit. This carbon was pretty thick and was hindering the flame propagation to the powder and increasing the primer blow-back and fouling I experienced. This drill bit has become part of my possible bag.

I'm waiting on the shipment of #63, #65, and #67 drill bits such that I can accurately measure the breech block flash channel. I believe that my Genisis breech plug came with a .032". I'll be taking my spare breech plug that I got from Traditions, that has a noticably smaller flash channel and drilling it out to .035-.036 for more positive BH209 ignition. Report to follow.

 

[Busta]

Thanks Carl, good information.

The Win W209's seem to be the longest I am aware of, I think a lot of manufacturers take that into account when making their plugs. Then when you stick a shorter primer in there, you get more than your share of blowback.

I have been testing a prototype breech plug, one easy way to find out how much headspace you have is to start with a clean primer pocket, measure the length of the primer, load it with no powder and fire it in the rifle, now when you remove it measure the length of the primer again. When you ignite a primer alone, it will set back the actual primer in the battery cup, lengthening it to your actual headspace between the front of the primer pocket and the breech block/standing breech/bolt face. Of course this method does not work on plunger type guns, for obvious reasons.

I did a test with the shortest Fed 209A, .295" long before firing, .305" long after firing. I then continued this test with the longest Win W209, .303" long before firing, .305" long after firing. This tells me I have a max of .305" of headspace, and probably about .008" too much for my preferred Federal 209A. I think a perfect headspace in a perfect world would be right at the max for your intended primer, that way you average length would be .001" to .002" less. Sure you are going to have a few as much as .003" or .004" shorter.

This is why you hear of guys having NO blowback, and guys having massive blowback with the exact same rifle/breech plug. Rifle/breech plug tolerances and primer brand/type tolerances. There just isn't a one-size-fits-all when it comes to 209 primers, not even close.

 

[SWThomas]

Awesome info! Thanks!!!

 

[CarlV]

Thanks Carl, good information.

The Win W209's seem to be the longest I am aware of, I think a lot of manufacturers take that into account when making their plugs. Then when you stick a shorter primer in there, you get more than your share of blowback.

I have been testing a prototype breech plug, one easy way to find out how much headspace you have is to start with a clean primer pocket, measure the length of the primer, load it with no powder and fire it in the rifle, now when you remove it measure the length of the primer again. When you ignite a primer alone, it will set back the actual primer in the battery cup, lengthening it to your actual headspace between the front of the primer pocket and the breech block/standing breech/bolt face. Of course this method does not work on plunger type guns, for obvious reasons.

I did a test with the shortest Fed 209A, .295" long before firing, .305" long after firing. I then continued this test with the longest Win W209, .303" long before firing, .305" long after firing. This tells me I have a max of .305" of headspace, and probably about .008" too much for my preferred Federal 209A. I think a perfect headspace in a perfect world would be right at the max for your intended primer, that way you average length would be .001" to .002" less. Sure you are going to have a few as much as .003" or .004" shorter.

This is why you hear of guys having NO blowback, and guys having massive blowback with the exact same rifle/breech plug. Rifle/breech plug tolerances and primer brand/type tolerances. There just isn't a one-size-fits-all when it comes to 209 primers, not even close.

Great info, Busta.........Thanks.

I didn't realize that primers "grew" like that. Hmmmmmmmm.........

I wonder if it would be possible to unscrew the breechplug a turn or so to get to a zero headspace condition.

Is that feasable or not safe?

Anyone know?

 

[younghunter_86]

SNIP:
I wonder if it would be possible to unscrew the breechplug a turn or so to get to a zero headspace condition.

Is that feasable or not safe?

Anyone know?

By no means am I an expert, but I'm going to say that is a BAD idea.

 

[Semisane]

QUOTE CarlV I wonder if it would be possible to unscrew the breechplug a turn or so to get to a zero headspace condition.

I really don't see a problem with that so long as the breech closes properly. You're only talking about a quarter or half turn. and the plug is backed up by the breech.

I did it with my Mustang before I switched to .25 ACP ignition. I was getting a lot of blow back with 209s. On that gun (a break-open) backing out the plug a little less than one quarter turn tightened the primer against the breech face considerably and helped a lot. If I backed it out any more than that I couldn't close the action.

 

[black powder]

when i had my little ROSSI 50 cal .i also unscrewed the breech plug a 1/4 of a turn and solved my blow back with 209s ..as long as u can close the action and it snaps into place u r ok ..

 

[SWThomas]

On a range day last weekend I reported that I experienced some hang-fires towards the end of the day using BH209 and Remington STS primers in my Remington Genisis.

The Genisis uses the rotating torch cam action to secure the primer into the breech plug. It doesn?t force the primer into the breech plug pocket like a bolt action might do, but simply keeps the primer from migrating backwards out of the primer pocket more than the clearance of the torch cam to the barrel. The seal is also the front of the primer in the bottom of the breech plug primer pocket.

I was thinking... When was the last time you reamed out the firing channel of your breech plug? That could be the reason for the hang fires.

 

[CarlV]

On a range day last weekend I reported that I experienced some hang-fires towards the end of the day using BH209 and Remington STS primers in my Remington Genisis.

The Genisis uses the rotating torch cam action to secure the primer into the breech plug. It doesn?t force the primer into the breech plug pocket like a bolt action might do, but simply keeps the primer from migrating backwards out of the primer pocket more than the clearance of the torch cam to the barrel. The seal is also the front of the primer in the bottom of the breech plug primer pocket.

I was thinking... When was the last time you reamed out the firing channel of your breech plug? That could be the reason for the hang fires.

I do believe you are absolutely correct. Possibly you missed this in my first post:

"In retrospect, I believe that the hang-fires I experienced the last range day were directly my fault by not realizing the fire channel in the breech plug was becoming severely carboned up and keeping it cleaned out every ?so many? shots with a 1/8 inch drill bit. This carbon was pretty thick and was hindering the flame propagation to the powder and increasing the primer blow-back and fouling I experienced. This drill bit has become part of my possible bag. "

 

[SWThomas]

Gotcha. My bad.

 

[Bucker]

simple

Maybe to simplistic but would it not make sense that the longest primer would A) get more fire to the load and B) Provide the least blowbacl as more is in the barrel? Why would you then shoot a short primer?

 

[UtahRob]

Re: simple

Maybe to simplistic but would it not make sense that the longest primer would A) get more fire to the load and B) Provide the least blowbacl as more is in the barrel? Why would you then shoot a short primer?

I wouldn't shoot a shorter primer just make things worse !!

 

[vabowhntr]

Busta,

Do you think the O ring trick you have used with the Huntsman/Sidekick aftermarket plug might work in other guns? I am using the Win 209's with a Rossi and getting more blowback than I would expect.

 

[CarlV]

when i had my little ROSSI 50 cal .i also unscrewed the breech plug a 1/4 of a turn and solved my blow back with 209s ..as long as u can close the action and it snaps into place u r ok ..

I checked this with my Genisis in the basement and with the primer I like to use, Remington STS, it only took 1/8 of a turn to keep the action from closing. I'm sure your mileage will vary depending on which primer you want to use since they are all different lengths.

I might try this next time I get to shoot, maybe not since I'm pretty sure I've learned that the key to consistant ignition, especially with BH209, is to make sure your fire channel is kept clean every so many shots.

Perhaps the BP rifle manufacturers will pick up on this and come up with a better "mouse trap" for breech plugs that won't foul up some day.

 

[vabowhntr]

Had to stop by the hardware store and get the o-rings on the way home. I tried both 9/32" and 1/4" and they both locked up tight with cheddite primers in my ss rossi miniloader. With the win 209s it would not lock up. I can't wait to try both o-rings and see what works. If this helps with blowback I might end up really liking this little gun, especially if it liked the 180 gr barnes I bought.