O-Ring In The Primer Pocket
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o-ring
I tried a few different o-rings in my knight lrh with the non-fpj plug this past fall to no avail. The center part of the oring would blow out and clog the front of the breach plug causing missfires about 10-15% of the time. Anyone have suggestions to try with this rifle and plug combo?
I tried a few different o-rings in my knight lrh with the non-fpj plug this past fall to no avail. The center part of the oring would blow out and clog the front of the breach plug causing missfires about 10-15% of the time. Anyone have suggestions to try with this rifle and plug combo?
Re: o-ring
What cross section "o"-ring were you using? I am using a 5-193 which is a .040" cross section. I have never experienced the problem you are describing and I have shot 100s of rounds using this "o"-ring in my Knight DISCs. Please provide some more information.
fisher2072 said:
What cross section "o"-ring were you using? I am using a 5-193 which is a .040" cross section. I have never experienced the problem you are describing and I have shot 100s of rounds using this "o"-ring in my Knight DISCs. Please provide some more information.
these o-rings are also to large for both of my NFPL conversion's that i've purchased (one about 9 mo.ago the other yesterday)both are very close to being blowback free.i have not measured what thickness of material i could put in there but i think even one washer might be to much.i'm thinking of making some out of .004+.007brass shim stock that i have.i have also noticed leakage out of the battery cup of the primer so at least some of my blowback can be contributed to that.for right now i'm pretty happy with my knight conversions but i really like everyone's vent liner mods ..........karl
We were talking about blowback at the club and one of the guys went home and made a rubber washer out of an bike inner tube with a couple of craft punches and put it in his CVA wolf and it fit with out any mods and reduced the blowback considerable. Said it was more trouble than it was worth but he was going to get some hi temp O rings and try it with them.
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Re: o-ring
Perhaps you can make a steel washer work. I was able to use an O-ring in my rifle yesterday morning, but this morning when i went to fire my rifle, i experienced the same difficulty you did. The center of the O-ring was pushed into the fire channel by the primer and clogged the flash hole so my rifle wouldn't fire. This happened twice, so i gave it up as a bad idea when the breech plug has a large diameter fire channel like mine does. The debris plugged the flash hole so tight i couldn't clear it with a torch tip cleaner, and had to use a # 70 drill.
I set out to use a washer much the same way Sabotloader did, and attempted to cut the washer smaller using the system he describes. The washer i found here in the shop, and i proceeded to make it fit into the breech plug. There was just too much material to remove with a file, so i gave up and installed the washer on a lathe, and cut it smaller as shown in the picture:
A letter 'C' drill was used to make the primer pocket deeper in a breech plug with flame cutting damage. The intention was to remove the flame cutting from the primer pocket and use the washer to reduce the depth of the pocket, so the primer would fit tight. The washer i found here was about 1/32" thick. The washer was cut to a diameter just a few thousandths larger than the diameter of the primer pocket, so that it could be installed, and would be a tight fit. The depth of the pocket, with the washer installed, ended up being 0.012" less than a factory breech plug, which seemed like it might work. It did, however, make for a tight fit when closing the breech on the Omega.
This morning i headed up into the hills to see if this thing would shoot. The blow back was virtually zero using this steel washer instead of an O-ring, and it was certainly was much better than it was before the flame cut damage was removed. It may be that one should make the primer height difference less than the 0.012" inch this ended up; perhaps 0.008" would be tight enough to have little blow back, and loose enough so it would be easier to put the rifle into battery.
fisher2072 said:
Perhaps you can make a steel washer work. I was able to use an O-ring in my rifle yesterday morning, but this morning when i went to fire my rifle, i experienced the same difficulty you did. The center of the O-ring was pushed into the fire channel by the primer and clogged the flash hole so my rifle wouldn't fire. This happened twice, so i gave it up as a bad idea when the breech plug has a large diameter fire channel like mine does. The debris plugged the flash hole so tight i couldn't clear it with a torch tip cleaner, and had to use a # 70 drill.
I set out to use a washer much the same way Sabotloader did, and attempted to cut the washer smaller using the system he describes. The washer i found here in the shop, and i proceeded to make it fit into the breech plug. There was just too much material to remove with a file, so i gave up and installed the washer on a lathe, and cut it smaller as shown in the picture:
A letter 'C' drill was used to make the primer pocket deeper in a breech plug with flame cutting damage. The intention was to remove the flame cutting from the primer pocket and use the washer to reduce the depth of the pocket, so the primer would fit tight. The washer i found here was about 1/32" thick. The washer was cut to a diameter just a few thousandths larger than the diameter of the primer pocket, so that it could be installed, and would be a tight fit. The depth of the pocket, with the washer installed, ended up being 0.012" less than a factory breech plug, which seemed like it might work. It did, however, make for a tight fit when closing the breech on the Omega.
This morning i headed up into the hills to see if this thing would shoot. The blow back was virtually zero using this steel washer instead of an O-ring, and it was certainly was much better than it was before the flame cut damage was removed. It may be that one should make the primer height difference less than the 0.012" inch this ended up; perhaps 0.008" would be tight enough to have little blow back, and loose enough so it would be easier to put the rifle into battery.
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My results were discouraging to. I thought about trying some teflon tape wrapped around the sides of the primer, of rubber dip on the primer sides " for dipping plier handles in ect." I'll try a few things when I get a chance to make it back out to the range. I might try turning down a washer too, it might be the best solution. I love how my knight shoots, but it sure takes a long time to clean up.
fisher2072 said:
My receiver area stays completely clean now using the "o"-ring and I have not had any misfires. When using the red FPJs, it use to take me 20-25 minutes to scrape and wire brush the hard build-up from the receiver area along with having one very weak fire that the bullet barely cleared the barrel. I only get some primer leakage on the bolt face now which wipes off using a Q-tip. I will be modifing my bolt in an attempt to fix this.
ronlaughlin said:
Ron,
Sorry I haven't been able to answer this earlier, but the pic of your o-ring with the seven primers tells me that you are compressing it too much. I have mentioned this in other posts before, that ideally you want about .015" of compression maximum. Less compression is better than more in this case. Too much will actually blow the center out of your o-ring and stick the rubber in the bottom of the flame channel, blocking the flash hole.
When you drill the primer pocket deeper with an angled drill, you are actually creating a funnel shape in the bottom. When you compress the o-ring too much, it actually forces the o-ring tighter toward the center. This closes the I.D. up a lot, then the primer blows out the center. I have went through this issue in several plugs over the last 2 years. Less compression is best!
Here is a pic of some primers I have shot with loads. My notes also tell me I fired 12 various primers before this 38 shot range session, so 50 primers in all. Notice the o-ring has not washed out much at all, and I probably could get another 25 to 50 shots on just that one cheap o-ring.
Contrary to what others might THINK, there is much more to it than dropping an o-ring in the bottom of the primer pocket, as you have discovered by actually testing this. The tolerances still need to be right for best performance, but ar much more forgiving than a solid material.
You would probably be better served by using the smaller diameter metric o-ring in the center of my pic? Less drilling and not as much center to blow out. The thicker o-rings work best in the Metrics Unlimited plugs that do not use a flame channel.
jsteurrys said:
jsteurrys,
I feel your pain with the standard FPJ plugs, they are the worst. I have a new plug/bolt modification design that seals the FPJ.
I have said it before, that the Knight bolt uses too large of a diameter firing pin, along with a not so uniform cast bolt face. The primers do not sit completely square and this allows the blowback to escape between the primer cup and battery cup. I have a design that utilizes a smaller dimater firing pin with a drill bushing for a bolt face/firing pin guide, but this is for another topic.
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Busta said:
Thank you for your advice. I agree there was considerable compression on the O-ring. It could be felt when i closed the breech on the Omega. I figured there should be some compression, but i guess there was too much. Another issue at play here was i was using a breech plug that had the fire channel drilled out with a #21 drill. I believe there would be less of problem, if i tried the O-ring in a factory breech plug with just the primer pocket deepened some. I just didn't happen to have any worn breech plugs without a modified fire channel laying around, and didn't do any work on a new breech plug.
At any rate, after experiencing success and failure with the O-rings, i headed in a different direction and tried out metal washers instead of the rubber O-ring. I purchased all of the O-ring they had at our local Ace, and had them special order 100 more for me, after my success with them the first day. I guess i will give O-rings a try again in the future, when a new breech plug suffers the flame erosion in the primer pocket.
My first trial with metal washers was yesterday, and the steel washer worked OK, but there was a very little blow back. The compression was about 0.012" compared to a factory breech plug, and that seemed some tight to me. It took effort to close the breech.
This morning i tried out an aluminum washer that started out as a backer washer for pop-rivet. It was turned down on the lathe, until it seemed it would make a nice fit. It is in the breech plug now, and it won't fall out any time soon. It ended up being about a 0.008" compression compared to factory. Here is a picture of 8 primers lit this morning:
One can see that the aluminum washer allows about as much blow back as an O-ring. The breech closed with a nice snug feeling, not like with the steel washer, where it seemed to be too tight. The 0.008 compression of the aluminum washer worked better than the 0.012 compression of the steel washer stopping blow back, and it felt more better when put into battery.
Three bullet speeds were timed at 13 yard, and they were 1752 fps, 1756 fps, and 1762 fps. To me, this consistency in speeds indicates a pretty tight breech. It seems i should make some more aluminum washers.
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Well, the aluminum washer idea for the primer seat didn't last a month. The Accura started belching blowback about a week ago, and the Omega started releasing black spent primers 3 days ago. I am thinking they were both working great for maybe 50 shot, and then they failed.
This sent me on to the next step which was suggested by Screwbolts quite some time ago. He suggested drilling out the breech plug, and tapping it to receive a grade 8, 3/8 x 24 bolt, and then use the bolt to make a new primer pocket. This was in response to my writing and showing a picture of flame cutting in the primer seat of my Omega, and Accura breech plug(s).
So, i drilled and tapped the worn Omega X7 breech plug to receive the grade 8 bolt.
Note that i ground the bolt end so that it would have a shape similar to the bottom of the hole made by the letter Q drill. I used 2 taps to make the threads, a normal tap, followed by a bottom tap. I wrapped the bolt with teflon tape, and made it super tight in the breech plug, so it won't unwind someday in the future.
I didn't think it would work so very well to cut the bolt off with a hacksaw, and it only took me 2 swipes, before i could see that was near hopeless. So, i put a cut disc on my 4" grinder, and proceeded to cut the bolt off. Following is a picture of the bolt nearly cut off; it was easy to do.
After the bolt was cut off, i used the cut wheel to sorta smooth the top. Note that one can see the edge of the bolt.
Then i started the flame channel using an 1/8" drill. My set-up didn't work so very well, thus the hole isn't centered.
Then i drilled for the primer pocket using a letter C drill. I wanted this breech plug to have minimum head space, so i was very careful with the depth of the cut, and went real slow here. When it seemed somewhat close, i ground another letter C drill to a flatter point, and used it to get the primer pocket closer and closer to the desired depth.
The breech plug ended up having a head space about 0.011" less than a factory breech plug.
This made for a condition where one can feel the action closing on the primer. One can readily put the rifle into battery, but there is a definite resistance, and it does compress the primer some.
Several primers were popped in the shop to verify this chingadero would work. This morning i went up, and shot 3 rifles at paper. I fired the Omega 3 times, raised the peep, and fired 3 more times. The spent primers are pictured along with a spent primer that was popped before the blow back was 'fixed', and a primer that was popped in the shop. One can see that the dimple made by the firing pin is some off center, which it always is even with a factory breech plug, but not this much.
The paper was near 102 yard, and the load was 105g BH209 pushing a 270g Gold Dot in a crush rib sabot lit by a W209 primer. I should also mention the breech plug has a vent liner installed. The vent liner was supplied by Precision Rifle, and is similar to a Savage vent liner, except it differs by having a 0.033" flash hole, and a larger vent opening that steps down to the flash hole.
This sent me on to the next step which was suggested by Screwbolts quite some time ago. He suggested drilling out the breech plug, and tapping it to receive a grade 8, 3/8 x 24 bolt, and then use the bolt to make a new primer pocket. This was in response to my writing and showing a picture of flame cutting in the primer seat of my Omega, and Accura breech plug(s).
So, i drilled and tapped the worn Omega X7 breech plug to receive the grade 8 bolt.
Note that i ground the bolt end so that it would have a shape similar to the bottom of the hole made by the letter Q drill. I used 2 taps to make the threads, a normal tap, followed by a bottom tap. I wrapped the bolt with teflon tape, and made it super tight in the breech plug, so it won't unwind someday in the future.
I didn't think it would work so very well to cut the bolt off with a hacksaw, and it only took me 2 swipes, before i could see that was near hopeless. So, i put a cut disc on my 4" grinder, and proceeded to cut the bolt off. Following is a picture of the bolt nearly cut off; it was easy to do.
After the bolt was cut off, i used the cut wheel to sorta smooth the top. Note that one can see the edge of the bolt.
Then i started the flame channel using an 1/8" drill. My set-up didn't work so very well, thus the hole isn't centered.
Then i drilled for the primer pocket using a letter C drill. I wanted this breech plug to have minimum head space, so i was very careful with the depth of the cut, and went real slow here. When it seemed somewhat close, i ground another letter C drill to a flatter point, and used it to get the primer pocket closer and closer to the desired depth.
The breech plug ended up having a head space about 0.011" less than a factory breech plug.
This made for a condition where one can feel the action closing on the primer. One can readily put the rifle into battery, but there is a definite resistance, and it does compress the primer some.
Several primers were popped in the shop to verify this chingadero would work. This morning i went up, and shot 3 rifles at paper. I fired the Omega 3 times, raised the peep, and fired 3 more times. The spent primers are pictured along with a spent primer that was popped before the blow back was 'fixed', and a primer that was popped in the shop. One can see that the dimple made by the firing pin is some off center, which it always is even with a factory breech plug, but not this much.
The paper was near 102 yard, and the load was 105g BH209 pushing a 270g Gold Dot in a crush rib sabot lit by a W209 primer. I should also mention the breech plug has a vent liner installed. The vent liner was supplied by Precision Rifle, and is similar to a Savage vent liner, except it differs by having a 0.033" flash hole, and a larger vent opening that steps down to the flash hole.
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What about using a bushing of some kind and a set screw on the side? The bushing would be a fairly tight fit with the hex set screw mainly as a backup and/or bushing adjustment for head space.
Sound possible?
Sound possible?
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GM54-120
What could work is a primer seat that is threaded something like the vent liners. One could turn it in and out to adjust the headspace. It could be locked in place by a set screw. However, i don't understand how the hex socket is made in the vent liners, unless perhaps it is cast. Making a hex socket in an adjustable primer seat is beyond my ability.
Aside from that, Screwbolts wrote he thought the primer seat made with the grade 8 bolt will last a long long time without flame cutting. Time will tell.
When those plugs you are trying fail, send them back, and i will repair them.
This morning i am going to try silicone o-ring in the Accura, which will be the third day of shooting. It has much promise. The silicone o-ring holds up much better than the rubber o-ring i have tried before, and i am hopeful they will be a good solution to blow back. Prepping a primer pocket for the o-ring isn't very difficult, and the silicone o-ring seems like it may last many shots, and is inexpensive.
What could work is a primer seat that is threaded something like the vent liners. One could turn it in and out to adjust the headspace. It could be locked in place by a set screw. However, i don't understand how the hex socket is made in the vent liners, unless perhaps it is cast. Making a hex socket in an adjustable primer seat is beyond my ability.
Aside from that, Screwbolts wrote he thought the primer seat made with the grade 8 bolt will last a long long time without flame cutting. Time will tell.
When those plugs you are trying fail, send them back, and i will repair them.
This morning i am going to try silicone o-ring in the Accura, which will be the third day of shooting. It has much promise. The silicone o-ring holds up much better than the rubber o-ring i have tried before, and i am hopeful they will be a good solution to blow back. Prepping a primer pocket for the o-ring isn't very difficult, and the silicone o-ring seems like it may last many shots, and is inexpensive.
deerslayer68
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updated my muzzy with an aftermarket 209 conversion.the primer hole is a touch short and a hair too wide making for a loose fitting primer.it came with a small tensil wire wrapped around it with a small pocket where it was to hold the primer in place.it broke the first time i used it....lol
anyway,here was my solution.
i wrap a couple rounds of teflon tape around each 209 which gives me a nice snug fit.
i eliminated most of the blowback but i'm half convinced blowback is enevitble and willing to deal with it as long as it's tolerable.
anyway,here was my solution.
i wrap a couple rounds of teflon tape around each 209 which gives me a nice snug fit.
i eliminated most of the blowback but i'm half convinced blowback is enevitble and willing to deal with it as long as it's tolerable.
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deerslayer68 said:
Not in my rifles it isn't. We feel there is no reason one can't have zero blow back in an Accura, or an Omega. Here is a picture of a few primers popped in my Accura over the last 3 days.
deerslayer68
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i can understand your point,guessing accura's and omega's are a break action type(breechloader) ?
i would want zero blowback as well.
was this a conversion to take advantage of blackhorn209?
i would want zero blowback as well.
was this a conversion to take advantage of blackhorn209?
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deerslayer68
What ML are you shooting?
What ML are you shooting?
deerslayer68
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bolt action,colorado legal
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