Titan ReloadingReloading EverythingRotoMetals2Lee Precision
MidSouth Shooters SupplyLoad DataInline FabricationWideners
Repackbox PBcastco
Page 1 of 2 12 LastLast
Results 1 to 20 of 30

Thread: Aluminium gas check failure

  1. #1
    Boolit Buddy andrew375's Avatar
    Join Date
    Jul 2005
    Location
    uk
    Posts
    307

    Question Aluminium gas check failure

    I cannot get aluminium checks to work with my .375 H&H. I've tried various thickness's of metal, .014" - .022" and get the same result; zero accuracy. My usual high velocity load of a 300 gr. round nose at 2200 fps give me groups under 3/4" at 50 metres. With aluminium gas checks I am lucky to get all the shots on to the 30" square backer.

    I've isolated the gas checks as the problem using the same batch of bullets, sized, lubed and checks seated identical. But the results are the same; Hornady checked bullets go in to nice small groups, alu. checked bullets all over the place. Even if I shoot alternate rounds of copper and alu. checked bullets I get the same result. They are not grouping at a different point of impact as they are going in completely random directions.

    The alu. checks snap on to the bullet base as they should and after sizing are quite tight and are the same diameter as the driving bands (.377"). Some of the checks do leave the bullet when the bullet exits the muzzle but have no sign of gas blow-by. I've examined the rifle bore with my Olympus bore-scope and there is no sign of lead fouling or of anything different from what I see when using copper checks.

    So what's going on?

    I also make checks from the same materials for my .30 caliber rifles and they shoot just as good as those with copper checks.
    "Consciousness is a lie your brain tells you to make you think you know what you are doing." Professor Maria Goncalves.

    If liberty means anything at all, it means the right to tell people what they do not want to hear. George Orwell.

  2. #2
    Boolit Mold
    Join Date
    Mar 2017
    Posts
    27
    This is just a guess, but maybe when they're separating, they're hanging on at some point throwing the trajectory slightly before it comes the rest of the way off. Are the Hornady gas checks separating or just the Al ones?

  3. #3
    Boolit Buddy
    Join Date
    Mar 2009
    Location
    eastern Iowa
    Posts
    472
    By now you are willing to try just about anything,I would think. Going on the idea it's the gas checks falling of just leaving the muzzle and not predictable at that.You could super glue them on. I do that with good results on some of my boolits. Get some glue on a toothpick and swirl it around the inside edge of the gas check. Snap it on the boolit. I have found it's best to wait for the glue to harden before sizing. If not hard yet the glue can ooze up and out of the gas check and get on the boolit and sizing die. The cheap superglue will work. You can get it four for a buck at some places.
    n.h.schmidt

  4. #4
    Boolit Grand Master

    Join Date
    May 2005
    Location
    Castlegar, B.C., Canada
    Posts
    7,928
    Are the aluminum checks the same diameter as the Hornady checks?

    Do they get sized onto the boolits so the swage on and are reduced in diameter? Could be they are loose on the GC shank or are not being sized down so are slightly too small to seal properly.

    Longbow

  5. #5
    Boolit Buddy
    Join Date
    Mar 2011
    Location
    Northern Illinois
    Posts
    142
    Quote Originally Posted by n.h.schmidt View Post
    By now you are willing to try just about anything,I would think. Going on the idea it's the gas checks falling of just leaving the muzzle and not predictable at that.You could super glue them on. I do that with good results on some of my boolits. Get some glue on a toothpick and swirl it around the inside edge of the gas check. Snap it on the boolit. I have found it's best to wait for the glue to harden before sizing. If not hard yet the glue can ooze up and out of the gas check and get on the boolit and sizing die. The cheap superglue will work. You can get it four for a buck at some places.
    n.h.schmidt
    I agree that the al checks are coming off and causing erratic accuracy. If you glue the al checks on it should confirm why they are not performing like the Hornady's. Hornady checks are made with an internal burr(for lack of better term) that grabs the shank of the boolit and digs in better. The al checks may seem tight but if you can pop them off easily with a thumbnail they will come off at some point and I believe cause inaccuracy.

  6. #6
    Boolit Buddy andrew375's Avatar
    Join Date
    Jul 2005
    Location
    uk
    Posts
    307
    Thank you for your replies they have given me more leads to investigate but I've still drawn a blank.

    I don't think the gas checks are coming off the bullet. I am shooting on an indoor, old railway tunnel, range and detached checks are pretty easy to see. Whilst some checks are detaching from the bullets I am finding only maybe 2 in ten shot at the most, certainly not every one. Also, I get a few of the .30 calibre ones detaching themselves but that doesn't seem to stop the bullets grouping into minute of angle or better.

    I've measured the checks before and after seating to see if they are undersized. As made they are .3785" - .379". They snap on to the bullet and wont fall off but can be pulled off with the fingers, check diameter is unchanged. After sizing the bullet comes out at .378. I've put ink on the checks and it is wiped off by the sizer so the check is being reduced by sizing. Also, after sizing the check is the same diameter as the bullet shank and can no longer be pulled off with the fingers, but will come off with pliers. I've tried checks made from metal so thick the wall of the check has been "smeared" upwards by the sizing die and they a DEFINITELY fixed on; but it makes no difference.

    But I will give the super glue a try; to eliminate that if nothing else. I don't consider it a solution though, it seems like too much time and effort.

    The bullets that do hit the target board are going in straight, not tumbling like you get as a result of gas blow-by. The rifle bore is not unduly fouled as I would expect if I was getting blow-by either.
    "Consciousness is a lie your brain tells you to make you think you know what you are doing." Professor Maria Goncalves.

    If liberty means anything at all, it means the right to tell people what they do not want to hear. George Orwell.

  7. #7
    Boolit Master
    Join Date
    Sep 2008
    Location
    NE Ilinois
    Posts
    1,937
    I have a Freechex II .38 Caliber GC maker. I modify the depth of the formed cup to fit on a Lyman 375449....the GC fits tight and doesn't come off when seated & the bullet is sized. It is extremely accurate.

  8. #8
    Boolit Grand Master

    Join Date
    May 2005
    Location
    Castlegar, B.C., Canada
    Posts
    7,928
    Okay, I just though maybe they might be slightly undersize and gas blow by causing an issue.

    Are they seated flat and square? Is the boolit base flat and square? A small angle there would cause erratic gas escape at the muzzle.

    If not something like that I am out of ideas.

    Good luck!

    Longbow

  9. #9
    Moderator
    RogerDat's Avatar
    Join Date
    Nov 2013
    Location
    Michigan Lansing Area
    Posts
    5,742
    When viewed with a magnifying glass are the aluminum and copper checks coming up the shank to the same point on the bullet or is there a little space at the top between the check and shoulder of the gas check shank? Are the lengths of the bullets the same length with both checks? Wondering if there is a slight difference in depth of gas check. If the check is not tight against the base inside because the check is "taller" and is stopped by the shoulder. That should make the bullet longer. Or if one check is shorter and doesn't reach the shoulder that might be a difference.

    Not sure what the effect of either one would be. Just speculating that there might be a small difference that allows the check to dish in the bottom or shift a bit due to not being snug against the shoulder.
    Scrap.... because all the really pithy and emphatic four letter words were taken and we had to describe this source of casting material somehow so we added an "S" to what non casters and wives call what we collect.

    Kind of hard to claim to love America while one is hating half the Americans that disagree with you. One nation indivisible requires work.

    Feedback page http://castboolits.gunloads.com/show...light=RogerDat

  10. #10
    Banned

    tomme boy's Avatar
    Join Date
    May 2011
    Location
    Clinton, Iowa
    Posts
    5,200
    Anneal your checks

  11. #11
    Boolit Buddy dimaprok's Avatar
    Join Date
    Mar 2017
    Location
    Evergreen state
    Posts
    424
    I am having problem with accuracy too. This is actually my first experience with gas checks, I made my own puncher from the plans I found somewhere on this forum, I was really excited that I can make my own gas checks 3 per penny, but accuracy is horrible, although my best group with GC was 2.37" at 50 yards. I did use very small bead of gel superglue and then resized which also pushes the gas check on tight, but not all were superglued. Going to try more super glue and one without GC.

  12. #12
    Boolit Master



    MUSTANG's Avatar
    Join Date
    Jan 2012
    Location
    Moapa, Nevada or Kalispell, Montana
    Posts
    2,733
    Quote Originally Posted by dimaprok View Post
    I am having problem with accuracy too. This is actually my first experience with gas checks, I made my own puncher from the plans I found somewhere on this forum, I was really excited that I can make my own gas checks 3 per penny, but accuracy is horrible, although my best group with GC was 2.37" at 50 yards. I did use very small bead of gel superglue and then resized which also pushes the gas check on tight, but not all were superglued. Going to try more super glue and one without GC.
    You should not have to super glue the checks on. Thickness of Check material (Aluminum or copper) coupled with correct diameter for the shank of the bullet should keep the check on when seated and sized.
    Mustang

    "In the beginning... the patriot is a scarce man, and brave and hated and scorned. When his cause succeeds, the timid join him, for then it costs nothing to be a patriot." - Mark Twain.

  13. #13
    Boolit Master


    Soundguy's Avatar
    Join Date
    Oct 2016
    Location
    N Central Florida
    Posts
    2,828
    I've had great luck with Vulcan checks, and hornady.

  14. #14
    Boolit Master




    Join Date
    Nov 2010
    Location
    Florida, where we call big dogs Deer
    Posts
    1,039
    From my experience with making aluminum gas checks (which I have had NO problems) if the gas check is loose on the bottom of the boolit, you need to use a thicker aluminum stock for making them. I have seen a lot of discussion, not nothing on the thickness of the aluminum stock that's being used for them. I get my aluminum from ACE hardware, they can order specific thicknesses as you want, anywhere from 0.008" to 0.020" which should accomidate what you need. Think the formula is ((sized boolit diameter) - (shank diameter))/2 = material thickness
    Gun Control means hitting what you aim at!

    Certified NRA Pistol Instructor
    Life Member of the NRA
    Life Member of the Disabled American Veterans Association

  15. #15
    Boolit Buddy andrew375's Avatar
    Join Date
    Jul 2005
    Location
    uk
    Posts
    307
    Ok, sorry for being away for so long, amongst other things I've had a week at Bisley where I confirmed that there is indeed nothing wrong with my Ruger; at 300, 500 and 600 yards.

    I've gone through all your comments and suggestions and I can confirm that the checks are seating properly, with the bullet base flat and square and a slight gap between the top of the check and the bottom edge of the lower driving band. The check is being sized down and is the same diameter as the bullet. I have tried two different thickness's of metal; .016" and .020". Checks are tight enough that I need pliers to remove them.

    Earlier this week I tried Tomme Boy's suggestion and annealed some checks. They did seem to fit better and appeared harder to pull off. This time I put up a large piece of backing paper along with the target (10 meter air pistol card) set at 50 metres (55 yards) Load was 48 gr. Lovex D060 for around 2100 fps. With Hornady checks the bullets grouped as usual at about an inch or so. With the (annealed) aluminium checks the first bullet went about 2" right of the existing group, no big deal as I had forgotten my sling. The next bullet went about 8" high and the following about a foot low. One missed completely and the last went 4" high! The interesting thing was that of the four, out of five, bullets that hit there was very little horizontal dispersion, 3 inches at the most. All the hole were circular.

    I picked up two checks from the range floor, about 4 yards forward of the muzzle and they both were missing a big section of the side wall, the bases were intact but about a 5th. of the periphery was torn off. I put the Olyimpus bore-scope down the barrel and there is no sign of lead deposits due to gas cutting or blow-by.

    I don't think checks coming off is the problem, I find plenty of my .30 cal checks on the range floor but I don't get any accuracy problems with them.

    I think my next test will be of lower pressure loads and test for a pressure threshold where the checks are failing.
    "Consciousness is a lie your brain tells you to make you think you know what you are doing." Professor Maria Goncalves.

    If liberty means anything at all, it means the right to tell people what they do not want to hear. George Orwell.

  16. #16
    Boolit Bub
    Join Date
    Feb 2009
    Posts
    34
    Look at some loaded rounds. If you see tiny scraps of aluminum at the mouth of the case, the checks are being damaged during bullet seating. If this is the case, you can try shooting them in unsized cases. Powder coating after seating the checks may also help.

  17. #17
    Boolit Buddy andrew375's Avatar
    Join Date
    Jul 2005
    Location
    uk
    Posts
    307
    Quote Originally Posted by Vern Humphrey View Post
    Look at some loaded rounds. If you see tiny scraps of aluminum at the mouth of the case, the checks are being damaged during bullet seating. If this is the case, you can try shooting them in unsized cases. Powder coating after seating the checks may also help.
    No case mouths a well expanded and chamfered. I also shoot plain base bullets and they relentlessly go into sub-moa groups when I do my bit.

    My next test is to mark the aluminium strip before making the checks. If I get the side walls torn off at the same place in relation to the mark then it will tell me there is something wrong with the tool.
    "Consciousness is a lie your brain tells you to make you think you know what you are doing." Professor Maria Goncalves.

    If liberty means anything at all, it means the right to tell people what they do not want to hear. George Orwell.

  18. #18
    Boolit Buddy Silver Eagle's Avatar
    Join Date
    Aug 2011
    Location
    Algonquin, IL
    Posts
    190
    You can try sectioning a checked bullet lengthwise to find out if the check is cutting into the shank of the bullet. If you are finding them on the floor they are obviously failing at some point. Maybe the rifling is cutting them all the way through to the shank. Try pushing one down the barrel with a rod if possible.
    Silver Eagle

    TANSTAAFL
    There Ain't No Such Thing As A Free Lunch
    - Robert A. Heinlein from "The moon is a harsh mistress"

  19. #19
    Boolit Buddy andrew375's Avatar
    Join Date
    Jul 2005
    Location
    uk
    Posts
    307
    I think I've stumbled upon what is happening. Following up on Silver Eagle's post I wanted to see if it is always the same bit of gas check ripped off relative to the bullet. To enable this I drew a line down the aluminium strip which would end up inside the cup and slightly off centre. I tried two material thickness's, .018" and .022". With the 22 thou' material half the checks came out with a chunk of the side wall missing, just like the checks I picked up off the range floor. Of the thinner ones I had the same but with only 2 out of 25. The holes in the strip are perfectly round so it is during the cupping operation that it looks like the metal is fracturing during forming. The checks that came out intact look ok but I'll take them in to work to look at them under the microscope. I'm just betting I'll see a whole load of cracks in the metal. So whilst the checks look good, under pressure of firing the part with the fractures breaks away being forced up in to the bullet diving band. What I have to do now is isolate the part of the tool causing the problem and modify it accordingly. I've already tried annealing the strip so I know it isn't a pre-existing fault in the material.

    Thank you Silver Eagle for for pointing me in a direction that lead to the discovery.

    Another thing I'll do is try some VERY down loaded rounds where I can pick the bullets up after firing to check for damage.
    "Consciousness is a lie your brain tells you to make you think you know what you are doing." Professor Maria Goncalves.

    If liberty means anything at all, it means the right to tell people what they do not want to hear. George Orwell.

  20. #20
    Boolit Bub
    Join Date
    Feb 2017
    Location
    Wilds of Southern West Virginia
    Posts
    65
    Do not discount a material problem. Rolling aluminum into a strip aligns the grain of the material in the direction of the rolls. Forming "against" the grain versus "with" the grain produces different levels of micro cracks. Annealing will modify this but will not completely eliminate the effect of grain direction.

Page 1 of 2 12 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