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Auto loaders and fast/slow powders?

Discussion in 'Uncategorized Threads' started by maclellan1911, Jan 25, 2008.

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  1. maclellan1911

    maclellan1911 TS Member

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    Is there a relationship between fast or slow burning powders and auto loader function. Or is it all preasure and gas volume or "bubble"?
     
  2. Steve-CT

    Steve-CT TS Member

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    Yes there is.

    Your powder needs to generate enough pressure over the gas ports to ensure reliable function, but not so much that the action is being battered.

    This is a function of the pressure curve over the ports.

    In my 1100 for example, I have had absolute 100% reliable functioning with my reloads using Remington STS or Nitro 27 hulls, RXP-12 wad, Remington 209 Premier STS primer and 17.5 to 17.7 grains of Red Dot. Having close to 300,000 reloads shot over 25 years with the STS since it has been available, (or its two predecessors, the bright green hulls of the mid 1980s and the Blue Magics of the early 1980s)and I never once had a bolt fail to completley lock back in singles, or cycle in doubles.

    The earliest one ounce loads in the early 1980s sometimes would not cycle or open an 1100 due to the pressure curve falling off too abruptly.

    Currently, I find the newer vintage Win AAs in the 2-3/4 dram 1-1/8th ounce variety to cause many problems. They are clean burning, and pattern extremely well, but I have a 50% failure rate of completely opening the action when using them. Literally a dozen from every box will either "stove pipe" or close up again with the hull still in the chamber.

    I do not have this problem with 3-dram eq Win AAs or "Silver bullet" handicap loads. I have noted that Patrick Flanigan, the exhibition shooter now sponsored by Winchester, is using 3-dram AAs in his Super X model 2 and 3 shotguns.

    Also, I find the Remington Premier STS factory loads to be very reliable in either the 2-3/4 dram eq 1-1/8th ounce or the 3-dram. The Nitros have been watered down a little since their first appearance about ten years ago and the lighter end loads have been tweaked up a bit over the same time frame. I find my reloads are more comfortable than 2-3/4 dr eq factories and I am "technically" loading 2-7/8ths dr eq.

    Pressure curves over gas ports are crucial to reliable and safe operation in other gas operated firearms, too. In rifles, for example: The M-1 Garand operates best with a narrow range of bullets from 150 grain to lighter loaded 168 grain match with a somewhat differently burning powder than used in .308 loads designed to replicate 7.62 NATO performance. Heavier bullets and too slowly burning powders put too much pressure over the port, causing op rod bending and bolt battering in the receiver.

    AR-15 style rifles need 15,000 psi over the port to cycle reliably. Some of the "cheaper" Russian import stuff like, Wolf, sometimes, short strokes an AR-15 style action (and some do not)

    Always consult and follow your loading manual and avoid factory ammunition brands and styles that cause problems in your firearm.
     
  3. hmb

    hmb Well-Known Member

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    You can fine tune your auto loader by changing the main spring. HMB
     
  4. Shooting Jack

    Shooting Jack Active Member

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    HMB, I have a 1100 and purchased a Hastings barrel and it was a magnum barrel. It would not cycle most standard loads(3 dram 1 1/8) so I layed it to the side. Were you saying that I can change the main spring and it will cycle the lighter loads. It only had one gas port on the barrel. If so, where can I get the springs. Thanks for your response. Jackie B.
     
  5. phirel

    phirel TS Member

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    maclellan1911- The difference in time for a fast powder and a slow powder to reach maximum pressure (3-5 10/000 of a sec.) will not affect the operation of an automatic.

    Pat Ireland
     
  6. jimrich60

    jimrich60 Member

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    Autoloaders are often very finicky about which loads function well, particularly light loads. With lighter loads, they often fail to fully cycle.
    I had this problem with my Beretta 391, which worked fine with "standard" loads, but would not cycle/eject lighter 1 oz loads and really had problems with the 7/8 oz loads I use in my combo. After talking with Cole Guns, and following their guidance, I replaced the gas spring with one of their heavier ones, and then I gradually shortened the recoil spring (1/2 inch at a time only!) until the gun functioned perfectly with the lighter loads I wanted to use. Note that with the shortened/lightened recoil spring, the gun cannot be used with heavier loads safely, but I also bought extra recoil springs from Coles, which are easily changed out if I need to use heavier loads in the gun some time.
     
  7. Steve-CT

    Steve-CT TS Member

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    I respectfully disagree with Pat Ireland's statement.

    My experience with autoloaders, particulary with Remington 1100s is quite extensive and I can unequivocally and confidently state that the burning rate and its effect on the pressure curve over the gas ports does matter a great deal.
     
  8. BDodd

    BDodd TS Member

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    No slam at Sir Pat but I remember someone on here, at least a couple of years ago, discussing slow V fast powders in automatics with a guru at Alliant. The gist was that the powder rep. opined that the slower burning powders DID provide a little better reliability with the auto loaders. Fortunately, I don't have a puppy in this debate and even less experience....breakemall....Bob Dodd
     
  9. Steve-CT

    Steve-CT TS Member

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    During the early 1980s, I participated in the field testing of Remington-Peters very first experiments with one ounce loads, shooting hundreds of them
    at the former Remington Gun Club in Lordship (Stratford, CT) alongside other trapshooters and Remington ballistic technicians who also participated and recorded the results.

    The earliest shells did not reliably function the 1100. Some lots would not cycle at all.

    The ballistics team present during the test attributed this to powder selection and burning rate noting that peak was reached far earlier in the barrel and dropped off sharply by the time the gas pressure had reached the ports.

    Powders were then tested and reformulated to provide a better pressure curve over the ports and cycling ability was restored.

    The subject remains central to the functioning in other gas operated firearms as I noted earlier.

    Mr. Ireland's comment above is incorrect.
     
  10. maclellan1911

    maclellan1911 TS Member

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    Ok so now, Which powder burnrate is more better for autos? fast or slow?
     
  11. primer

    primer TS Member

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    18 gr of 700X, Winchester Wad, Rem primers in any case works just fine.
     
  12. mrskeet410

    mrskeet410 TS Member

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    I guess I was the first to post about the ‘gas bubble’ and its affects on autoloader reliability. I learned about it this way.

    I’m a long time autoloader user. I used mostly Red Dot. I never had persistent autoloader problems with Red Dot, but I had some. I went to PB, and my malfunctions went to almost zero. This struck me odd, since PB had much lower pressure than Red Dot.

    As you are aware, PB prices seriously inflated, so I went back to Red Dot. This time I noticed a marked increase in malfunctions. I had some International Clays that I bought for a 20 gauge load, and I loaded some of that in my 12 gauge. Malfunctions dropped to almost zero. I called Hodgdon regarding my International 20 gauge load and mentioned as an aside that I found it odd that lower pressure International, and PB, gave such higher reliability in my autoloader. The Hodgdon rep didn’t find that at all odd. That’s when I first heard about the ‘gas bubble’, and that both PB and International Clays were similar in that they both produced a large ‘gas bubble’.

    It is the pressure in that ‘gas bubble’ as it passes over the gas ports that produces the energy to work the action. The chamber pressure is something else. Max chamber pressure is reached before that wad leaves the hull. This is what I was told by the Hodgdon rep.

    Believe it or not.
     
  13. smifshot

    smifshot TS Member

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    much todo about nothing. Some posters here seem to know all there is about nothing. Have shot 1100s since they were first sold and have never had different kinds of powders make a difference in the way they operated. If you load by the book, the shell should operate the gas guns without problems. 17-18 grains of Red Dot with 1 or 1 1/18 ounces shot will work unless you have gun problems. I expect the folks at Alliant and the other powder manufacturers have all they can do without calls from us asking rather trite questions. Fred
     
  14. Neil Winston

    Neil Winston Well-Known Member

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    I have to agree with Steve and not Pat. The Beretta 303 I shot for years would shoot everything - everything, that is, except three-dram AA's, though light AA's worked just fine. There's more to this than bare burning-rate, that's for sure.

    Neil
     
  15. Southern Gent

    Southern Gent TS Member

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    I guess I'm just lucky. I have a 390 that I've shot everything in from 3/4 oz. "Cowboy" loads to turkey loads in, and it's never missed a beat.
     
  16. phirel

    phirel TS Member

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    Steve/Neil- I have no problem accepting that I am wrong, but first, I need some explanation. Lets compare two similar loads with a fast and a slow burning powder. The fast powder will reach a peak pressure of 10,000 PSI in about 3/10,000 of a second and the slow burning powder will reach the same pressure in 5/10,000 of a second. In both instances, 10,000 PSI is reached before the bolt begins to open. How can 10,000 PSI from one load be different from 10,000 PSI generated by another load?

    Neil- Is it possible that you had a quite peculiar Beretta 303?

    Pat Ireland
     
  17. Steve-CT

    Steve-CT TS Member

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    Pat, it's a curve. The burning rate and pressure generated and length of time pressure reaches peak and how rapidly it falls off can be displayed on a graph.

    A short peak, faster burning powder will reach a sharp peak more quickly and fall off more rapidly.

    I know Red Dot is fairly fast, but it is a consistent burner and it doesn't fall as fast from peak as some others do.

    I've never had a problem with 17.5 to 18.0 grs of Red Dot with all Remington components on an ounce and an eigth load.

    When "Jiggs" Cochran was alive, he used to explain the burning rate to us.

    What it boils down to is how much pressure is needed to cycle the action and does the load being fired generate that pressure over the gas ports where it is needed. You can have two loads that reach 10,000 psi peak, but if one load has fallen well below the pressure needed to drive the action compared to the other by the time the gas column crosses the ports, you're going to have short cycling problems. Conversely, if you have too much pressure over the ports, you're going to have an action cycling too violently.

    I can't remember offhand what is needed for a 2-3/4" chambered 1100. Also the old 1100 skeet barrels came with slightly larger diameter ports than did the trap and field versions to get more gas for light loads.

    But I can relate this to the M-16 rifle (or AR-15) the 5.56 NATO cartridge is generating about 52,000 psi chamber pressure. However, over the gas port four inches from the muzzle at the front sight base, that gas column needs to be at 15,000 to 16,000 psi to cycle the action on an M-16 or AR-15.

    One of the problems that has been reported from the field about the M-4 carbine version of the M-16 is that their actions shake themselves loose after a while compared to a regular, full length M-16 because the ammo was designed for the longer barreled version, beause the M-4s are getting beaten harder due to higher pressure over the gas ports and hence, a more violent slamming of all the moving parts.

    Some non NATO spec ammo, like Russian Wolf, for example uses powder that has a pressure curve below that level of pressure at that point in the barrel. I have a Bushmaster XM-15 that will short stroke with Wolf about once in every five shots. When I switch to Lake City NATO headstamped XM-193 55 grain ammo or XM-855 62 grain ammo - I can run about 500 rds in an afternoon without a problem (except I will clean every 150 or so rounds)

    Same thing goes for the M-1 Garand. There is a very specific range of bullet, powder combinations that are optimal for the Garand so that the action isn't cycled too violently.

    I have been a member of the Garand Collectors association, and in their magazines, they ran articles showing pictures of warped operating rods and even receiver heels that broke off due to strong impact from the bolt due to improper loads with higher than intended pressures OVER the GAS PORT.

    This is why we had developed "M-2" ball ammo for the M-1 rifle. The original ammo used in the Springfield '03 was called ball, M-1 and was a heavier, bullet, close to 180 grains in weight and with a slower powder. No gas system. No problem. When the M-1 Garand came out for testing in the 1930s, the ammo was shaking the rifle apart. They engineered the M-2 ball load with its 150 grain bullet and a powder that put the right amount of pressure over the port.
    Essentially, they "watered down" the original .30-06 load so that it would work optimally in the M-1.

    Sorry for the long ramble, and please understand I am not engaging in a flame war of any type. I'm simply raising the issue of pressure cuvrves and why they are crucial in gas operated autoloading actions.

    Shoot well and often!
     
  18. phirel

    phirel TS Member

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    Steve, pressure over the gas ports is the key. My problem was that peak chamber pressure is probably reached well before the wad leaves the hull. I am looking at two pressure curves now for Green Dot and Red Dot. The difference in the tails of the curve appear insignificant and this is when the gas would pass over the ports.

    I agree with you that something is happening in the automatic cycle but my mind cannot correlate it with the pressure curves of fast and slow powders I have. Can you give me some detail an the pressure required to cycle a typical automatic and the distance from the chamber to the gas ports. I could estimate the time required for the gas to reach the ports and then apply this to the curves. Now I an just stuck on having a problem with about one 10,000 of a second making a difference in how the gun would cycle.

    Pat Ireland
     
  19. Steve-CT

    Steve-CT TS Member

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    Well, I will go and measure the distance from the chamber to the ports.
     
  20. hmb

    hmb Well-Known Member

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    Jackie B.,

    I did not purchase special springs. I would use a regular main spring and clip 3 rings off and test the gun. If it still did not function I would use a tapered reamer and open the gas ports a little. It also helps to clean and polish the action rod assembly and lube with Break Free. HMB
     
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