Can you guys tell me (clean up language) this guys is trying to say?!?

Discussion in 'General Discussion' started by joshua99ta, Sep 23, 2010.

  1. joshua99ta

    joshua99ta Well-Known Member

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    i found this on a forum not pertaining to guns at all but there is a sections for guns and hunting and stuff .... so can SOMEBODY translate the point this guy is trying to make?!?


    How many of us here shoot something like a 50 or 55 grain bullet in a 1:8 or 1:9 twist .223? Or maybe a 1:8 twist in one of the various 6mm rounds? We all have at onetime or another.
    Last night I was up late with Parker and his wisdom, and here's some thoughts I stole out of his mind:

    * the bullet enters the rifeling, and starts a chain reaction as well as the well known reaction. When the bullets enters the rifeling it actually twists the barrel as it is pushed the the barrel, and the the like reaction occurs when the barrel will actually uncoil. In otherwords the barrel becomes a giant coiled spring

    * The difference in energy lost from the rifeling in a 1:14 twist barrel and the now in vogue one and eight twist is roughly 25%. It takes much more power to push a bullet thru a fast twist barrel than a slow twist barrel. When you increase the resistance to the bullet going thru the rifeling you also induce a like action into the barrel material, and as the bullet passes by the like reaction occurrs with the barrel trying to "unwind" (I bet Calffee never thought about that one!!). So in the end the more resistance, the more stress is added into the barrel after ignition

    * Now that we've completely abused the barrel, lets see what elses happens. The bolt is the next victim. As the barrel tries to twist, it also tries to move the chamber end, and the bolt face (the hotter the load the more pronounced this is). This energy is then transfered to the actual reciever frame. Then of course it over reacts the other way on the return trip to the static position. We ain't done!

    * how many of us have just had to have a "speed lock" kit? GUILTY as charged! Light weight firings pins and heavy springs are nothing but a crutch to help fix an engineering problem. (Mauser, Winchester, and 700 Remingtons come to light here). Think about it a minute; the case slides into the chamber very easilly, so it obvious there some clearence there (as it should be). You lock the bolt into position to then set the correct headspace (I hope you did this right). You release the firing pin and it strikes the primer. The rest is history. But alas we all want those magic lock time numbers. We add a titanium firing pin (a harmonic distortion problem in itself), and a spring that looks and feels like it's a left over purple stripe race hemi valve spring. Now the firing pin hits the primer like a sledge hammer, and actually shoves the case forward (so much for headspace). It hits the primer so damned hard that it acts like a tap dancer in the face of the primer. If the firing pin strikes a few thousands off center it cocks the case sideways ever so slightly creating a displacement laterally. What we should be after is one clean strike just good enough to set the primer off on a dead center axis to the centerline of the case. But alas we had an engineer design into this equation a four inch long firing pin and a very short bearing surface to guide the firing pin into the primer. In reality a 1.5" firing pin is all we need in a properly designed bolt. Use a small return spring (both in weight and size). Without the spring being contained inside the firing pin itself; we also take all the harmonics associated with hardened steel out of the firing pin. And the return spring acts as a shock absorber. Anybody here know what the lock time king is? I'll give you a hint; it's none of above and they also are not pretty.
    gary
     
  2. BobbyL

    BobbyL Well-Known Member

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    Some good points and some bad ones but either way im not about to touch this one.....
     

  3. joshua99ta

    joshua99ta Well-Known Member

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    LOL I just thought it was funny that he made these statements and gave no reasoning as to where the origin came from or a point of making these statements...
     
  4. Coyboy

    Coyboy Well-Known Member

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    Ask Trickymissfit, almost sounds like one in the same.

    Basically talking about the tourque produced by fast twist and Heavy bullets. Really not going to feel it in a .224 bore shooting 55 grain bullets. Now a 308 or338 shooting heavy bullets it is very noticable. Been a known and adressed issue for quite some time and has been adressed by action and stockmakers alike.

    The lightened fire pin and heavy spring has also been a known issue for about as long as it's existed. In BR rifles a well known HOF has proven his rifles shot better with the standard bolt guts.

    Not alot of enlightenment in this guys post.
     
  5. winmag

    winmag Well-Known Member

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    Probably a college kid, who jumped off the deep end at a party, and got all warped in the puff puff give sequence....... Too bad. If he had a decent knowledge of firearms there was hope at one time, but after a post like that Im affraid he's joined the dark side. Saw some crap like that happen to a couple guys I knew in college. 1 day they were normal country boys, the next they turnned into hippie stoners. What a waste!
     
  6. J E Custom

    J E Custom Well-Known Member

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    Good advice !!!

    But this is a discussion web site .so I will attempt to shed a little light on some of these
    statements if I can.

    First= as cowboy said it is not a problem with light bullets unless you have an extremely
    light barrel contour like a #1 and even then it probably wont have enough effect to worry
    about. most people use heaver barrels and this all but eliminated this phenomena.

    This does occur in large bore rifles with heavy bullets and light barrels but not as bad as
    the poster made it out to be. It does not straighten the barrel rifling out. In fact the high
    speed film of a tank barrel upon firing only showed about 3 to 4 degrees of rotation with
    a very large projectile.

    So with proper bedding and barrel diameter this effect can be controled to a point of no real
    effect on accuracy. one of the main reasons that bench rest shooters use heavy barrels is
    stiffness and torque resistance.

    Fast twist barrels are to stabilize the heaver bullets at the slower velocities they reach. But
    can be problematic if lighter/faster bullet are used because of jacket separation from the
    Inertiaof the bullet when coming in contact with the rifling. This a good place for gain twist rifling.

    The slower the twist with the same velocity the less chance of this happening but the greater
    chance of not stabilizing the bullet, so the proper twist rate is very important.

    As to the issue of velocity difference between a 1 in 14 and a 1 in 8 twist = it is no where near
    25% more like 25 to 50 ft/sec at best.

    Now for the fireing pin issue.
    The main reason for going to a lighter fireing pin is to improve lock time !!!! the reason to
    improve lock time is to make up for inconsistent trigger control by the shooter (The faster
    the ignition process the less time the untrained shooter has to move positions or follow
    through). this is one of the reasons that the well trained and practiced shooters find no
    advantage in them.

    The heaver spring improves the lock time but it also makes up for the loss of inertia of the
    lighter fireing pin.

    Also any fireing pin will move the case forward if the head space is improper but it can't "Drive"
    the case beyond the allowable headspace. And if the firing pin protrusion is correct the firing
    pin stop prevents very much of this from happening.

    Another reason that I use the speed lock springs Is the diameter . they are smaller and will
    normally reduce the drag of a serpent like spring inside of the bolt (The smaller diameter
    spring coils in line and does not touch the inside of the bolt.

    All of the things he mentioned can cause some problems if combined in the wrong
    combination but most gunsmiths that build accurate rifles know how to avoid these problems
    areas and don't worry about the theory just work around it.

    This is just my opinion based upon my experiences and is certainly not the last word in these
    areas.

    J E CUSTOM
     
    Last edited: Sep 23, 2010
  7. joshua99ta

    joshua99ta Well-Known Member

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    Thank you JE!!!

    I kind of read the post on another forum and I was thinking "this guys is smoking some good stuff" I've done lots of reading and these points he brought up have never been something I have read about. I'm no accomplished long range shooter by any means.... I'm still a beginner and have been without a rifle to actually do any shooting for almost a year now.
     
  8. J E Custom

    J E Custom Well-Known Member

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    No problem.

    It is good to ask questions, and as far as learning I make it a point to try and learn something
    every day and after over 50 years of shooting It happens quite often.

    This is a good web site to learn things if you are interested because there are Lot's of
    knowledgeable folks on it (I am not including my self because I am still learning).

    Keep asking questions and someone will have a/the answer hopefully.

    J E CUSTOM
     
  9. shortgrass

    shortgrass Well-Known Member

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    A+++ and agree completley, Jim. That guy had to to have 'strained' himself! Probably took a full week of intense? thought. Unfortunately, our world is traveling further and further in his direction. Not enough 'doers', too many 'thinkers/analyzers'. So many, I'm considering changing my post signature. How's this; "Gunsmithing,,, So easy a caveman can do it!"
     
  10. joshua99ta

    joshua99ta Well-Known Member

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    this guys is still @ it!!!! LOL Im enjoying it... he makes some good points but some of the stuff he says is funny!


    here is one... i believe the rifle in question is a 223

    That's pretty much what I was saying. The excessive torque from the overly fast twist not only shocks the barrel into a twisted stress, but it also transfers this to the action. Then as the bullet passes the barrel and the reciever react in the opposite direction. Take this into fact as well as the actually movement of the entire rig (stock and all) in the bags. I see this greatly exaggerated in my 1:8 twist 6/250AI on a 13+ pound gun (105 grain AMAX bullets at a hair over 3000 fps). I'd like to try this same load out in a 1:10 twist barrel at 3100 fps
    gary