Titan ReloadingRepackboxMidSouth Shooters SupplyRotoMetals2
Load DataWidenersPBcastcoReloading Everything
Lee Precision Inline Fabrication
Page 3 of 7 FirstFirst 1234567 LastLast
Results 41 to 60 of 132

Thread: The real story on Gas Checks

  1. #41
    Boolit Grand Master



    cbrick's Avatar
    Join Date
    Dec 2005
    Location
    Kalifornia Escapee
    Posts
    8,034

    Checks holding boolit in rifling??

    Great thread, it should be a sticky.

    Like every response in this thread I too have my SWAGS.

    Such as the check holding the boolit to the rifling. SWAG . . . the check is the last part of the boolit to enter the rifling, if the boolit is not already turning at the twist rate of the barrel and requires the check to do this I would think you have far worse problems than a possible benefit or detriment of the check. I wouldn't want to have to try and clean that barrel . . . gas check or not.

    I don’t believe for a second that being a “heat shield” is any part of the function of a check. Lead absorbs heat very slowly; much to slow for the micro second it’s in the bore to “melt” the alloy. If the heat of the burning gas could melt lead why doesn’t paper or plastic shotgun wads melt or burn? Or even discolor them? Copper, or worse yet aluminum checks absorbs heat far faster than does lead (and aluminum checks do work) so how could a check be a “heat . . . “shield”?

    Let’s say you have an extremely high quality bore and your rifling starts off at .030” wide. Even the best made barrels cannot maintain that .030” perfectly for the length of the bore, at some point it’s going to narrow a bit to say .027” and then widen to say .031”. Once the boolit is engraved to .030” and then reaches the narrower part high pressure gas leaks by with the very same effect as an acetylene torch cutting steel. This is NOT melting, it is a high pressure abrasive gas cutting and stripping it. This is where a check, a properly functioning lube AND A PROPERLY FITTED BOOLIT of a SOFT ENOUGH ALLOY for the pressure can have a big effect at reducing or stopping leading. Too hard is in all probability the cause of more leading than using or not using a check. Too soft an alloy usually gets the blame but too hard is more often than not the cause but even this to a large degree can be minimized by a properly fitting boolit. A poor fit and too hard an alloy and there’s trouble in paradise, gas check or not. In addition to sizing the checks I am completely anal when casting, boolit bases for long range loads, i'ts a perfect base or it's no better than a sprue regardless of what the rest of the boolit may look like.

    I am a firm believer that checks must be fitted flat against the base of a perfect/flat/square boolit base. The higher the velocity and the longer the range the more important this becomes. If a check is installed crooked, think of that last instant as the boolit leaves the bore (think freeze frame photo) and one side of the check is still in contact with “one side of the rifling” by only a few thousands of an inch but because of the crooked check the other side is free of the bore completely. There is still pressure pushing the boolit, not peak pressure but pressure none the less so where is the boolit going? Two things I can be reasonably sure of; 1> not straight and 2> not where you want it to go. I have made up punches to size checks flat (taking out the concave) and slightly flaring the sides of the cup. They slip on fully and easily, fit flat and crimp on tight.

    I think the check does help scrape the bore and helps keep it cleaner by scraping powder, lube and any minor leading from the previous shot. I think the checks adds strength to the boolit base and helps minimize base deformation which would allow higher pressures to be used.

    These are some of my SWAGS on checks and I’m sticking to them . . . right up until I change my mind.

    Rick
    "The people never give up their freedom . . . Except under some delusion." Edmund Burke

    "Let us remember that if we suffer tamely a lawless attack on our liberty, we encourage it." Samuel Adams

    NRA Benefactor Life Member
    CRPA Life Member

  2. #42
    Boolit Mold
    Join Date
    Mar 2009
    Location
    Atlanta, Georgia
    Posts
    7

    The real story on gas checks

    Ok, then here is the next question. If you eliminate the gas check and just use a filler will that load A) shoot accurately, B) produce leading to a significant degree, all assuming a #2 alloy???

  3. #43
    Boolit Grand Master

    Join Date
    May 2005
    Location
    Castlegar, B.C., Canada
    Posts
    7,928
    I haven't pushed the limits using filler but have gotten very good results with moderate loads in my .303 British under plain base boolits and 314299's without gas check. I was getting leading even with gas check before adding filler. Using loads with filler has allowed me to get the same performance as gas check loads without the gas check and no leading.

    I don't have any "proof" at this point, just opinion, but I have read a couple of articles that say much the same.

    A side by side comparison test would have to be done to get any kind of consistent results for various loads, velocities and pressures. In fact many tests would have to be done to get "proof": hard versus soft boolits, fast versus slow powders, different diameters, different weights, different checks, different fillers, etc.

    Fillers seem to work for some people and not for others and they may not be suitable in some cartridges especially those with large body, small neck and steep shoulder.

    If I get time this summer I will try to run a test of gas check versus filler loads in my .303 from say 1600 - 1800 FPS up to where things go bad. I have loading data for up to at least 2250 FPS for gas checked boolits.

    If I get this done it will be limited to my gun and the powders and boolits I have available. I have been wanting to do this anyway so maybe this thread will get me kick started! I haven't been shooting near enough for a while.

    Longbow

  4. #44
    Boolit Master

    mtgrs737's Avatar
    Join Date
    Jun 2007
    Location
    Kansas land of OZ
    Posts
    1,940
    IMHO the only thing gas checks do to a1600fps or under boolit is lighten my wallet! And I am much too tight to allow that! LOL!

    Sorry for the humor in a very serious thread!
    Mtgrs737
    Still Learning!

    NRA Life Member
    Life long OZ resident

    Personality type: Compulsive/Excessive - I don't know what that means, all I know is, if I like something, I want a lot of it!

    Pray to put "One nation, Under God" back in our country! We will never be a Great Nation without HIM!

    SOCIALISM is a PHILOSOPHY of FAILURE, the CREED of IGNORANCE and the GOSPEL of ENVY, It's inherent value is the EQUAL SHARING of MISERY. -Winston Churchill

  5. #45
    Boolit Master


    HangFireW8's Avatar
    Join Date
    Dec 2008
    Location
    Central Maryland
    Posts
    2,587
    Quote Originally Posted by Calamity Jake View Post
    "2. That it prevents the super-hot sand-blasting effect of the powder gasses from melting the lead base of the bullet, which in turn leaves lead in the bore..."

    The hot gasses are not in contact with the base long enough to melt it.

    I did an experiment not long ago with a cutting torch(1800+°), I applied this heat to the base of a 30 cal WW boolet with someone using a stop watch, it took aprox. 2 seconds to show signs of melting on the base.
    I just found this and have to comment on it.

    Did you run that cutting torch at 20,000 PSI, and then focus that pressure a few thousandths wide right on the edge of the bullet base?

    If not, you've tested something, but you've proven nothing about what goes on in a barrel.

    -HF

  6. #46
    Moderator Emeritus
    dromia's Avatar
    Join Date
    Mar 2005
    Location
    UK. Sutherland & Co Durham
    Posts
    5,134
    Another intelligent, informative thread based on actual knowledge and experience, Cast Boolits at its best.

    Stickied!


    For fine firearms and shooting requisites visit my Web Site by clicking the link below:

    Pukka Bundhooks

  7. #47
    Boolit Master
    Join Date
    Nov 2008
    Location
    NE Florida
    Posts
    701
    I have also been pondering on the hows and whys of gas checks. I know they work, as I have seen the results. I have always tried to seat them square with the base, but I have often wondered how much effect it would have, when the base of the bullet gets hit with 25,000 to 30,000 PSI. I have shot many thousands of bullets with gas checks and have recovered hundreds of them and have several findings; 1. Hornady crimp on gas checks seem to stay put on the bullet into the berm. 2. I fired some very old Lyman slip on gas checks in my .44 mag rifle and a good number of them came off in flight, I found most of them about 10 yards down range. 3. In my .44 Mag I sized the bullets to .431 and the Hornady gas checks measure .431 at the front edge, the Lyman checks measured about .429 at the front edge, both shot accurately and neither loads caused any leading. I recently got some freechex in both .44 and .30 calibers. The free chex are smaller in diameter than Hornady gas checks, but seem to function well, I am still testing these to see if they are as accurate as Hornady. The more I think about gas checks, the more unanswered questions I have.


    G

  8. #48
    Boolit Master
    Join Date
    Jan 2009
    Location
    Southeast Louisiana
    Posts
    587
    As a relative *** to this site this thread has given me much for thought. I am trying to work up some loads for my 8x57 with Milsurp primed cases that I have pulled the bullets and powder from. I will be using the primed cases and pulled powder under my Lee 175gr.RN cast bullet with #2. Have often wondered about the need for gas checks. It may take some time before I actually get these loads together but I will try some checked and some un-checked and see what the results are comparing velocity, accuracy, leading and just overall performance. (Doubt I will be able to recover any of the boolits fired but I will try) I will also use a filler (lint) for some and no filler for others to compare the need for such. Interesting experiment as I will have some gas checked with and without a filler and some un-checked with and without a filler. Also sized and unsized boolits. As I said it may take awhile before I get all of the results but will post back when I do.
    Great thread with a lot of good input.
    If a man has nothing greater to believe in than himself, he is a very lonely man.

  9. #49
    Perma - Banned


    Bret4207's Avatar
    Join Date
    Mar 2005
    Location
    St Lawrence Valley, NY
    Posts
    12,924
    Quote Originally Posted by keeak View Post
    Ok, then here is the next question. If you eliminate the gas check and just use a filler will that load A) shoot accurately, B) produce leading to a significant degree, all assuming a #2 alloy???
    It all depends, or as we say up here, " 'pendz on". What cartridge, what load combo, what design boolit, does it fit right in the first place, etc., etc. If you were talking a 32-40 at 1450 fps for instance, yeah it might well work just fine. If you were talking a 22-250 at 2000 fps you might just as well stop now as fillers don;t generally work too well in cases of that shape.

    Gotta be a bit more specific to say one way or the other.

  10. #50
    Perma - Banned


    Bret4207's Avatar
    Join Date
    Mar 2005
    Location
    St Lawrence Valley, NY
    Posts
    12,924
    Quote Originally Posted by HangFireW8 View Post
    I just found this and have to comment on it.

    Did you run that cutting torch at 20,000 PSI, and then focus that pressure a few thousandths wide right on the edge of the bullet base?

    If not, you've tested something, but you've proven nothing about what goes on in a barrel.

    -HF
    Applying it to the edge isn't duplicating a barrel either. The whole base is under pressure. But I know what you're saying. That's why I like to add all those little qualifiers like, "it seems to indicate" or "the theory is...".

    Until one of use can get inside a barrel and watch it's all theory.

  11. #51
    Boolit Master
    Join Date
    Jan 2009
    Location
    Southeast Louisiana
    Posts
    587
    Quote Originally Posted by HangFireW8 View Post
    I just found this and have to comment on it.

    Did you run that cutting torch at 20,000 PSI, and then focus that pressure a few thousandths wide right on the edge of the bullet base?

    If not, you've tested something, but you've proven nothing about what goes on in a barrel.

    -HF
    I'm an old weldor and fitter by trade. You don't run a cutting torch any where near that pressure to begin with. Not even in the hundreds. You don't have anywhere near that amount of pressure in any of the oxygen or different type of gas bottles you may be using.
    If a man has nothing greater to believe in than himself, he is a very lonely man.

  12. #52
    Boolit Grand Master 303Guy's Avatar
    Join Date
    Oct 2008
    Location
    New Zealand
    Posts
    9,078
    This boolit was fired with a case filler but without the gas check. The gas check rebate should theoretically have been subjected to equal pressure in all direction but the peening shows that did not happen. I have other PB that show 'sand blasting' marks. This would indicate that the boolit is not being subject to a plasma but rather, burning granules of powder. (The plasma is there all right but so is a lot of burning granules of powder).


    This next boolit was a bit different in that its base was protected by a wax sabot.


    Both boolits were paper patched.

    This boolit was loaded without filler (and also no g/c). Flame cutting is exacly where it is to be expected - the groove ridge.


    Here we have boolit with the rifling 'ridge' somewhat narrower than the groove in the barrel. The lead section has the same 'wear' as the gas check.


    This one shows base deformation due to boolit displacement in the bore.


    And without the gas check - same thing (just worse) - but no gas cutting.


    I'm not sure what to make of it all.
    Last edited by 303Guy; 05-30-2009 at 03:12 AM.
    Rest In Peace My Son (01/06/1986 - 14/01/2014)

    ''Assume everything that moves is a human before identifying as otherwise''

  13. #53
    Boolit Master


    MakeMineA10mm's Avatar
    Join Date
    Apr 2007
    Location
    Central Illinois
    Posts
    2,198
    Wow. This has given me more to chew on than I expected, and I'm still not sure we're at the end...


    Part of the problem may be too many variables. Maybe if we can analyize one set of circumstances, we can then address variables from there.

    Taking Rick's idea of a freeze-frame photo a little farther, let's go SUPER-SLOW-MOTION in the firing of the cartridge with a gas-checked boolit...

    First, let's assume that the loaded round is perfect - bell-mouthing, seating, and crimping all went well, so we have an ideal, non-deformed boolit loaded concentrically in the case.

    Second, let's assume that we used a flat or flattened gas check that is perfectly flush and flat against a perfect boolit base. Nothing out-of-balance or alignment.

    Third, let's assume it is a crimp-on gas-check, so we needn't debate the issue of it coming off at this point in time.

    Fourth, let's assume we've sized the boolit (and GC) to throat size, and the barrel is .001" smaller in groove diameter than the chamber's throat. (i.e. "perfect")

    So, here we are waiting for the hammer to fall.

    I guess the first point we have to address is what kind of cartridge is this and what kind of powder load are we using? Let's say it's a 44 Magnum with Elmer's classic load of 22.0grs of 2400 powder with the Thompson 250gr SWC boolit.

    With this we have at least two circumstances we will have to vary latter on: First, we have a medium-sized load of powder (well above loads of Unique, W231, Bullseye, but well below loads of 3031 or RL-7 in a rifle cartridge). Second, we have a straight-walled case of bore diameter, so the expansion ratio is pretty low (vs. a necked rifle cartridge where a lot of gas/pressure/heat/powder granules are funnelled into a smaller place).

    Hammer falls, primer goes off, powder at the rear of the powder load ignites and begins to release large amounts of energy. This increases heat and pressure inside the case and the gases energetically move around the un-ignited granules of powder. Obviously, these conditions all act on the base of the boolit via the gas check.

    At some point while all of this is going on and heat and pressure continues to rise and more of the granules ignite, the pressure inside the case causes the bullet to overcome the restraint of inertia and the crimp. The boolit begins to move forward. (Now, I think there are lots of questions that need answered here... Like, what percentage of the powder load is ignited and letting off gas, what percentage is still un-ignited granules and what percentage have completely combusted and converted to gas??? -- All of these will have an effect on the torture being given to the boolit's base...)

    Someone who knows more than me, take over from here....
    Group Buy Honcho for: 9x135 Slippery, 45x200 Target (H&G68), 45x230 Gov't Profile, 44x265 Keith


    E-mail or PM me if you have one of the following commemorative Glocks you'd like to sell: FBI 100yr, Bell Helo, FOP Lodge1, Kiowa Warrior, SCI, and any new/unknown-to-me commemoratives.

  14. #54
    Boolit Bub
    Join Date
    Jul 2009
    Location
    Honolulu
    Posts
    51

    Smile Flgc

    Quote Originally Posted by Bullshop View Post
    The gas check increases the shear strength of the alloy so can allow higher pressure than the alloy alone. It acts as a drive gear, geared to the land/groove of the barrel and geared to the boolit in reverse, inside the check.
    I think it has little to do with sealing the gas, pressure takes care of that. In fact I think a gas check at pressure below or just barely adaquit of what is needed for obturation may prevent a good seal. Depending on how high the pressure is the base is what will obturate to make a seal. The higher the pressure the more length of the bullet will obturate. If pressure is not high enough to obturate past the check you may loose the seal. Most leading problems in revolvers is not from too soft a boolit as many think but just the opposite they are too hard for the pressure used. Read Dave Scovilles book loading the peacmaker for some good info on that. What the gas check is doing is making a harder boolit from a softer one.
    With a given hardness of alloy a PB boolit can shoot quite well up to a limit in pressure after that limit it needs a gas check and after that limit it need a harder alloy and after that limit it needs a FLGC.
    About your last question I remember when the desert eagle gas operated 44 mag semi auto came out. In their operator manual they said it could be used with cast boolits but only with gas check. I think now they say no cast, why? I have used them and Garrands, and carbines with nothing but cast with no problems with lead build up in the gas systam. Lotsa folks here doing that.
    BIC/BS
    A FLMJ is practically a jacketed bullet. Why can't a thin wall tubing and GC make a FLGC that is easy to use and effective?

  15. #55
    Boolit Man
    Join Date
    Aug 2009
    Location
    on top of a wind swept ridge
    Posts
    79
    evening all, I'm new to this forum but would like to share some facts about metal, heat & pressure. You see I had worked in the aluminum extrusion industry for 15 years and I learned a few things in that time.

    First to allow you all to try to get on the same page of thought, look at a child's Play-Doh factory. You take a hunk of the doh and work it back and forth, while transferring the heat from your hands to help soften it. Then you place it in the factory and press the lever down forcing the doh through a "die" , so basically under heat and pressure the doh
    "flows" through the die forming to the die shape.

    Now to aluminum, you take a billet (a log of aluminum) and heat it to about 900 degrees F and force it through a heated die at about 2800 to 3500 PSI, and under the heat and pressure (and don't forget that you create heat in the die by friction) and the aluminum flows through the die to the form and size you want. Things to be considered also are alloy, die wall thickness, how clean the metal is (dirt is a killer of dies) the speed at which you force the metal through the die (this will dramatically increase the buildup on the die and force you to pull the die from production) and other small things to boot.

    So the things to keep in mind are these:
    alloy
    heat
    pressure
    speed
    friction & dirt

    its all about doing a balancing act ....... try to keep these things in mind when developing a pet load for your use.

    How well you figure your alloy % is a factor

    How hot you choose to load

    How much pressure you get with the load

    How fast you choose to push the bullet

    How well the fit/size diameter, lube and how well you drossed

    OK, now does everyone feel like they are on the high wire ???

  16. #56
    Banned

    Join Date
    Dec 2007
    Location
    soda springs Id.
    Posts
    28,088
    you forgot time/pressure curve or how long the powder pushes against the base of the boolit.

  17. #57
    Boolit Master
    Join Date
    Jan 2006
    Location
    SW Idaho
    Posts
    2,264
    I have a Wildey in 45 Win Mag. Think of it as a 45 acp case 1.198" long. They warn against using even GC lead bullets as the ports bleed off pressure to operate the pistol. If I get to tinkering and the lead bits clog those ports, how might I clean them? With a $1500 autopistol I hesitate to do something that might lead me to having to "fess up" and send the assembly back to Wildey for cleaning.

    Rich
    DRSS

  18. #58
    Boolit Master

    Join Date
    Aug 2007
    Location
    Lesage WV
    Posts
    2,433
    you will get that I found that Kroil works {thats from my moulds} I have a S&W 460 and put about 200 lead through it .
    They have extra compendator for lead. It will LEAD bad. After 2 hrs the first time . I soaked it in Kroil and next time about 10min and was cleaned.

  19. #59
    Boolit Master
    lwknight's Avatar
    Join Date
    Nov 2009
    Location
    Fort Worth, Texas where the west begins
    Posts
    3,416

    Cool

    This is a great thread!!
    I started trying to learn this gas check business 30 something years ago and its still ambigues at best.

    From all what I read here and other places and my own exp, I gather a few rule of thumbs. Or rules of thumb whatever....

    1. The appearant abrasions in the bottom of the naked bullet are actually powder being pressed into the bullet. This will be most noticable in full capacity loads where the ingited powder gas actually forces the powder next to the bullet to extreme inertial pressure against the heavier bullet.. It is not powder burn at all.

    2. Gas checks can gear to the rifling even when the bullet skids a bit or even a lot, therefore is able to actually scrape some lead off the barrel.

    3. Poor boollit fit and too hard and too hard boolits are bad things.

    4. Leading usually starts at the forcing cone and starts smearing farther down the more you shoot.

    5. Good lube is as important as oil in your cars engine.

    I think and would hope that the GC does have some springback so it will scrape the barrel, if that really does happen.

    I think that it is possible in some cases that the checks do in fact help seal the bore untill onturation takes effect. At which pointthe gas check no longer matters.

    Everything else is still up in the air.
    Anyone else get any rules of thumbs from all this and other places?
    Sent from my PC with a keyboard and camera on it with internet too.
    Melting Stuff is FUN!
    Shooting stuff is even funner

    L W Knight

  20. #60
    Boolit Mold
    Join Date
    Feb 2008
    Posts
    14

    Talking

    Quote Originally Posted by shotman View Post
    I will make a comment I dont rememberof digging out any boolits with the gas check attached. do any of you? rick


    Yes always the gas check is still attached to the base of the boolit. and sometimes there is still a little lube left in the lube grooves. this is in a 41 mag, 45 colt,and in the sub calibers--357mag, and the 44 mag.

Page 3 of 7 FirstFirst 1234567 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check