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Post by ET on Jul 30, 2010 21:35:40 GMT -5
It seems the subject of recessing a the BP is appearing again. Now I found some small gains in doing this and two out of three of my BP’s are recessed. Some are thinking of what about the 3rd one. Well it’s being saved for another experiment down the road. Yeah, I know I can’t leave well enough alone.
So lets have a look at that experiment and see what others think about it. Currently we are of a mindset using a single diameter for the recess. Now what would happen if a dual diameter recess were to be employed? Lets say a 5/16”” diameter recess a 1/4” deep with a continuing recess of say 17/64” diameter another 1/4” depth to the head of the vent liner. Now my train of thought is focused on a more controlled progressive powder burn. I don’t want to say more so as not to poison the well, influence thoughts someone else has when they look at this concept.
I’m putting this out for your thoughts, pros or cons are welcomed.
Ed
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Post by Richard on Jul 31, 2010 16:44:33 GMT -5
ET...............Why not just put the plug in the lathe and bore a taper or cone effect rather than stepping it? By now though, you would be turning the vent head pretty small. Not giving a lot of surface on the taper to seal against the gas pressure? Richard
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Post by ET on Jul 31, 2010 19:54:24 GMT -5
Richard
I don’t believe sealing will be an issue if I keep the vent head size close to recess size.
With a 5/16” diameter recess I am getting a little more velocity that I can only contribute to having a smaller chamber at the start of ignition. So if I try to put any reasoning behind it I see a small increase in pressure for that small velocity gain. Now the question, is it because of just overall pressure gain or slightly sharper spike rise? If it’s a sharper spike rise then that also has to have an affect on degree of obturation. Here a cone I don’t think would give me the possible response I’m hoping to see. Okay the well has gotten a little poisoned here. ;D
Thanks for responding to my thread.
Ed
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Post by DBinNY on Jul 31, 2010 22:06:42 GMT -5
ET, I would guess that you get a slightly sharper spike combined with a little higher pressure because you are burning the powder in a more confined space.
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Post by ET on Aug 1, 2010 8:05:28 GMT -5
ET, I would guess that you get a slightly sharper spike combined with a little higher pressure because you are burning the powder in a more confined space. DBinNY I was hoping someone else would also consider or see the possible affect of using a smaller chamber area of the initial start of the powder burn as I do. You did. For some reason I can’t get the new 250SST (FTX) bullet to shoot as tight a group as its hard nose predecessor. If there’s a change in the lead hardness then it might need a little more kick in the butt to regain the level of obturation and hopefully see the same level of performance again. Eventually my small stock of hard-nose bullets will dissipate and the only choice will be FTX in the class of 250 bullets such as SST & SW. For some reason the 250 SST & SW bullet really likes the 2300-2350fps range in my 1-24 twist 10ML-II using 4759. So I’m not seeking any real velocity gains but hope to regain the performance I’m used too when forced to use the FTX bullets. This considered approach is just a possibility that I will eventually explore once completing some other experiments first. Thanks for your reply Ed
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Post by Richard on Aug 1, 2010 19:50:33 GMT -5
You did say 5/16" going down to 17/64" right? 5/16 is .312" and 17/64 is .264". So, you would have to grind down the vent head to at least .264 which would trim most of the taper??? Richard
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Post by ET on Aug 1, 2010 22:43:48 GMT -5
You did say 5/16" going down to 17/64" right? 5/16 is .312" and 17/64 is .264". So, you would have to grind down the vent head to at least .264 which would trim most of the taper??? Richard Yes but even with a small taper area the next contact area is threads. I give my vent liners a good snugging down with nickle based anti seize. I feel this should be sufficient to prevent any pressured gas bypass. If I'm wrong I'll be red-faced admitting it. ;D Ed
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Post by Jon on Aug 2, 2010 4:49:16 GMT -5
Et. The ml1 uses basically a set screw with a hole drilled in it. I hope they are still available since I only have 2 left. I will be checking soon. I may look into making some. I don't shoot the ml1 that often so it may be just as efficient to buy a couple. You can't get much smaller than that and you could give the plug a good taper. Let me know how you make out. I'm always looking for a better mouse trap. Jon
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Post by ET on Aug 2, 2010 7:15:35 GMT -5
Jon
I enjoy reading your post. Never having actually owned or seen what we commonly refer to as a 10ML-I I found your remark about the vent liner used for it interesting. Never really considered a setscrew for a vent liner candidate but a point I’ll keep in mind. To be honest I wasn’t really thinking about a better mouse trap, as much as how to address getting the FTX to respond better than what I am getting with it. There was mention in the past that the lead now could be a little harder and I believe the mention of using a few additional grains of powder was used to get decent groups. Here again I’m trying to avoid velocity change.
The reason I chose ¼” depth for the 2-different diameters was because I felt it was a good starting point and willing to extend that depth to 3/8” for both if needed. Hopefully I will find a sweet spot somewhere in there that will give me what I want. The only reason I’m not starting this right away is because I still have a few experiments to finish and don’t want to be tempted to be drawn away from them. Yeah I’m easily tempted when a diversion appears. ;D
No problem with reporting when I reach that point and Thanks for your reply.
Ed
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Post by edge on Aug 2, 2010 7:55:57 GMT -5
Sealing would not be an issue at all and you could taper as small as you want. Just buy the ML-1 vent liners or make your own.
A word of caution though, the ML-1 VL should be loosened and re-snugged down every 25 shot or less. Since the Allen Wrench is small and the hex tends to fill with carbon. I would also make sure the VL does NOT go below flush in the BP since carbon will fill the threads and they will be hard to remove with the wrench....but they drill out easily from the nipple side....been there and done that ;D
edge.
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Post by ET on Aug 2, 2010 10:54:10 GMT -5
Edge
With your knowledge gained from your experience with BP’s and vent liners your comments are greatly appreciated.
If a thread seal is not an issue then I will have no problem bringing down the secondary dia. to ¼” and still have good amount of meat surrounding the allen head slot on the current VL. The use of a setscrew now intrigues me after 2-individuals mentioned it and now opens another possible doorway to something I have been seeking that I could not get with the current VL configuration. Have to inquire as to what hardness available in setscrews?
Oh boy, I feel this diversion with more exposed possibilities really starting to yank at me. ;D
Thanks Edge
Ed
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Post by Jon on Aug 2, 2010 10:58:54 GMT -5
Et listen to edge he's the man and been around before I was even thinking about smokeless. All I'm trying to do is catch up with all the knowledge of people on this board. Keep up the good work and the thought process. Follow the history of the savage and now the remington the nef etc. We are only working on the begining now if we had better sabots to choose from there would be less people shooting sabotless. We now have the cooling rod. I'm going to get into sabotless but it is kind of scarry. No fudge factor. Keep up the good work. Let us know what you come up with. It wasn't that long ago people were afraid of the recessed plug. Jon J
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Post by edge on Aug 2, 2010 11:19:33 GMT -5
Just don't use a set screw too long without breaking it loose as many many folks found them stuck and had to drill them out edge.
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Post by ET on Aug 2, 2010 23:05:00 GMT -5
Jon
You’ve made some good points. When the recessed BP appeared I feel it was more apprehension than fear for me. But hey I found it was a slight improvement when I tried it. Now my 1st fear with a muzzle-loader (Black Powder) was when I squeezed the trigger the 1st time and got CLICK. Here I sat at the bench not knowing how long I should hold it in this position. After about 5-minutes I got the nerve to pull back the bolt. No Primer.
Good luck with your new project and I also look forward to hearing your results. I imagine after your 1st shot your nervousness should disappear quickly. Here I envy your resolve to move forwards on this project even with what you are emotionally experiencing.
Edge
Noted and Thanks
Ed
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Post by ET on Aug 4, 2010 10:19:20 GMT -5
Got up this morning and after 2-cups of coffee I headed out to do a quick errand. Man it was toasty warm and was glad to get back home into air conditioning. Sitting at the table I pondered what I could do today that would be productive and a haunting thought crept in. At first I resisted of starting this but when the added thought of the basement being even cooler snuck in well I was overwhelmed and couldn’t resist anymore. ;D Half-hour later she’s done and ready for 1st round testing with this approach. Ed
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Post by Richard on Aug 4, 2010 15:04:20 GMT -5
ET.............Just curious? ?Why not make the point from the edge of the vent liner to the rim of the plug, a straight taper as I indicated earlier??? Simple enough with your new toy. Then there would be no restriction to the flame travel from the primer flash? ?? Right now, you have powder hiding on that first "shelf" out of the line of flame travel? Richard
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Post by ET on Aug 4, 2010 16:37:11 GMT -5
Richard
You make a point for consideration. Maybe a little more taper at the transition point of the 2-different diameters of the recess might be beneficial. My limited concept at the moment is having a smaller chamber intact with a specific dimension for that hopefully initial start of a sharper spike rise that would give that FTX a little harder kick in the butt.
The initial flame from the primer should already start the powder burning once it enters the first smaller recessed chamber and then it should just be a powder-burning cascade to the next diameter recess. Once the flame from the primer hits a wall of powder and begins the burn I can’t see it affecting the powder that further along other than help carrying the burn. But this is just hypothetical reasoning that I’m going on so I can’t vouch for the validity.
Now if I see vent liner binding from carbon as Edge previously cautioned about to watch for or possible early sabot disruption then my recourse would be the addition of a taper at the transition point as mentioned reducing the sharpness of the pressure rise spike.
Will find out when I’m ready to start testing.
Thanks for your input.
Ed
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Post by Jon on Aug 4, 2010 18:54:16 GMT -5
Et keep up the interesting work. You may have found an answer or another question. You can always try tapers no shelf on top you could always taper down to a 1/4 in. Everything is an experiment. But that is the way improvements are made. Beat of luck. Jon
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Post by ET on Aug 4, 2010 22:46:33 GMT -5
Jon
My inquisitiveness is starting to peak a little as to the results waiting to be seen. Hope the final result ends on a positive note. It’s nice to learn but more rewarding when some kind of accomplishment is achieved. We shall see.
Thanks for the wish of luck with this one.
Ed
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