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10mm, lug lock-up

Discussion in 'Handguns: Autoloaders' started by Beagle-zebub, Jul 18, 2008.

  1. Beagle-zebub

    Beagle-zebub Well-Known Member

    I have some questions concerning the 10mm cartridge.

    1. Do full-house loads take their toll on the pistol? (I'm thinking a Dan Wesson in particular.) 1911Tuner has made some comments to the effect that .45 Super and (I think) full-house 10mm jar the locking lugs to the point that they eventually become loose and sloppy; comments posted by others have lead me to believe that heavier recoil springs may even exaggerate this, since they slow the slides rearward movement at the moment of recoil, and slam the slide back into battery that much harder. What's the full story on all this?

    2. Is there anything that can be done to clear up the problem of casings ejecting too far?

    3. Does something like a Sprinco buffer address the first problem?
  2. mbpautz762

    mbpautz762 Well-Known Member

    some thoughts...

    I have had a Dan Wesson Pointman7 10mm for about a year now. I reload and shoot factory ammo in it. I've only shot about 1500 rounds in it so far, but about 90% has been either full-house, or near-max reloads. I have had zero problems or slop with the locking lugs so far, and the gun is just as tight as it was when it left the factory. even "too tight!" as one of my friends commented. no slop so far, but we'll have to wait to see what happens when about 10,000 rounds are down the pipe.

    2. try installing a heavier recoil spring. I usually use 20-22lb wolf springs. it still flings the brass pretty far, but I don't like the feel of the heavier springs. I used to use a 24lb which kept the brass in line, but I was worried it was going to batter the frame a little too much.

    3. I haven't used the sprinco, but from what I've heard, it will reduce the slide's velocity gradually, mostly near the end of slide travel. if that's correct, it won't have any effect on the locking lugs, since unlocking is the beginning of the slide movement. however, it should reduce your recoil, as well as frame battering.

    hope this helped, and maybe someone with a little more experience will offer their advice.
  3. Beagle-zebub

    Beagle-zebub Well-Known Member

    Good to hear! Your good experience, and your response itself.

    I have ambitions of getting a 10mm Pointman just like yours

    The way I imagine a Sprinco helping lug wear would be by reducing the spring-resistance exerted at the beginning of recoil--whereas a normal spring snaps right into the full (or near-full) tension of the recoil-spring, one assembled with a Sprinco in it would only have the primary springs resistance at first, a slower progression into spring-resistance that would mean less torque on the lugs. Such as why Sprincos diminish felt recoil, I'm thinking. Was the assembly on the Delta Elites the same sort of contraption?
  4. atblis

    atblis Well-Known Member


    Hotter loads loosen up guns faster. Yep. That's a fact of life.
  5. The Lone Haranguer

    The Lone Haranguer Well-Known Member

    According to the gun scribblers, at least, this problem was fairly prevalent in the old Colt Delta Elite, using the original "wrist-wrencher/gun-breaker" (this also according to the scribblers) Norma load that approached the .41 Magnum in power. I would not expect that from a newer-production gun with milder ammo. However, the harder you run any machine, the sooner something will break.
  6. freakshow10mm

    freakshow10mm member

    I have an aluminum framed 10mm pistol that has seen well over 20,000 rounds of full power (215PF+) and has shown no meaningful wear.
  7. 1911Tuner

    1911Tuner Moderator Emeritus

    Checked the headspace lately?

    20,000 essentially proof-level rounds in a gun that was originally designed for 19,000 psi...even with modern steels...and you really expect that there hasn't been any meaningful change in the critical dimensions?
  8. freakshow10mm

    freakshow10mm member

    I checked headspace before I sold the top end (switching from 4 inch bull to true 4.25 inch bushing barrel with a Caspian slide). Can't say there was a noticeable difference.

    The loads I shoot in my gun aren't even close to proof loads. 34-37K psi is well within SAAMI spec.
  9. 1911Tuner

    1911Tuner Moderator Emeritus

    Lemme try again...

    The gun was designed for 19,800 psi and very little has changed.
    Modern metallurgy has bumped that up to about 22,000 psi...aka+P...and proof level is 25% above that...or about 27,500 psi as an absolute maximum. Most are proofed at 25% above the SAAMI standard of 19,800. Proof level pressures aren't intended to be the gun's steady diet.

    Also, pressure isn't the only issue. It's not even the main one. Recoil impulse against the breechface and the lugs...and the "stretch" area between them is where the trouble begins.

    When the barrel lugs start to deform and set back, and the slide stretches between the breechface and the first lug wall...headspace increases by a like amount...and it's in the kaboom direction.

    If the slide cracks in the corner at the top right or bottom left of the port...and it usually happens at the top right, just forward of the breechface...the increase occurs all at once. One round is fine, and the next one is catastrophic.

    I have a modern Colt .45 slide here that cracked in that area due to the owner hot-rodding the gun with handloads...trying to break a thousand fps with 230-grain jacketed bullets.
  10. atblis

    atblis Well-Known Member


    19,800psi in 45 caliber though. 10mm is a smaller caliber.
  11. Old Fuff

    Old Fuff Well-Known Member

    Also there is the issue of dwell time (how long it takes for the slide and barrel to unlock). On some pistols this is controled by a cam, (think Browning Hi-Power or Glock) and the dimensions can be changed to alter the dwell time and increase or decrease it within limits.

    The Browing design uses a link, not a cam; and as a consequence the dwell time can't be changed much. Some not-too-bright folks address this by over-springing the pistol by going to a 20 pound or more recoil spring and a bunch of buffers.

    It doesn't work.

    What it does do is cause battering of the slide stop pin and lower lug and link pin when the gun is driven into battery, and it reduces critical run-up (the distance between the slide's most rearward movement, and the back of the magazine well.

    If Browning was still alive he would have some strong words to say about those that are determined to do things that the pistol was never designed or intended too do, and then complain when things don't work out - at least in the long run.

    Unfortunately they're is no known cure for stupid... :cuss: :banghead:
  12. Beagle-zebub

    Beagle-zebub Well-Known Member

    Is there any 10mm pistol that is on the right side of this?
  13. Old Fuff

    Old Fuff Well-Known Member

    And this makes a big difference?

    Rim diameter on the .45 ACP is .480". On the 10mm it's .425". In the real world that .055" difference won't have much effect on the thrust against the breech face. The important issue is slide velocity and the consequences of early unlocking while pressures are too high.
  14. 1911Tuner

    1911Tuner Moderator Emeritus

    The Bren Ten, most likely. Based on the CZ75, it was built from the ground up to deal with the recoil forces at work with the full-house loading. The Glock 10mm probably. Those are the only two 10s that I've examined, other than the 1911-based pistols in that caliber. There may be others.

    The 1911 is a very good pistol, but it's limitations in this area are due to the small radial locking lugs and the relatively thin material in the port between the first lug wall and the breechface.

    A few of us are old enough to remember the issues that Smith & Wesson had with the Model 19s and full power .357 ammo...which was a completely different animal than what we have today. The 158-grain SWC at 1400 fps from a 4-inch barrel was shooting the revolvers loose in short order. The topstraps were being stretched so badly that a simple tune-up with endshake washers couldn't correct the problems...and the only recourse was to replace the frame...or just cannabalize the gun and start over with a new one.

    Same deal with J-Frames and +P+ ammo. They just didn't live long. Some went south with as few as a hundred rounds. The Airweight versions could do that dance with about 50.

    The ammo companies attenuated the cartridge somewhat by going to an advertised 1235 fps...but adventuresome handloaders grabbed the baton and carried on.

    Smith finally threw in the towel and introduced the L-Frame revolvers that would stand up to a steady diet of the hard stuff...for a while longer.

    Why did SAAMI standard .357 Magnum ammunition destroy K-Frame revolvers While-U-Wait? Because the pretty little wheelgun was designed with 16,000 psi and the resultant recoil forces generated by a lead 158-grain bullet at those pressure levels. When they turned it into a .357 Magnum...it was a matter of "when" and not "if" the guns would start to come apart at the seams...and many did.

    The 1911 pistol and the K-Frame Smiths are fine sidearms...but they're not exceptionally strong sidearms. They're more than adequate so long as they're not pushed beyond what they were designed to do...but when we insist on trying to wring 10 gallons of water out of a 5-gallon mop...somethin's gotta give.
  15. atblis

    atblis Well-Known Member


    More than you might imagine. Area = pi*r^2. It actually comes out to a 21% difference in area (rather than simply a 11.1% difference in diameter).

    Do 9x19 or even 9x23 pistols have issues regarding durability in 1911s? They're running at pretty close to 10mm pressures or over (50kpsi for the 9x23).

    I do think that full tilt 10mm loads are a bit over the top. However, simply saying that the 1911 can't handle anything over 22kpsi is misleading because that applies to 45 acp.
  16. Old Fuff

    Old Fuff Well-Known Member

    Ya, they can. I have examined Colt Lightweight Commanders (or clones thereof) that developed headspace issues after being fired extensively with European surplus sub-gun 9 x 19mm ammunition. By the time you find out that your headspace has gone south it may be too late, and folks that shoot barn-burner loads through 1911 pattern pistols seldom have a set of headspace gauges. They don't need them because they know everything there is too know. Also in the 9mm/.38 class of ammunition you are usually pushing a much lighter bullet then those used in larger bores.

    Back when the gamers (who know a lot more then the rest of us - just ask them) were trying to shoot minor rounds that made major requirements they concocted some 9mm/.38 Super loads that were so hot that gunzines wouldn't publish them. They didn't blow up any guns that I know of, but additional wear and tear on their guns was well known.

    John Browning literally designed the pistol around the .45 ACP cartridge. The hole spacing in the link controlled the dwell time perfectly for this round. But it was something that couldn't be easily changed to accommodate cartridges that can have up to twice the working pressure. It is not by chance that later designs (Glock, Browning Hi-Power, SIG, H&K, S&W, etc.) used a cam rather then a link. It is also not coincidental that high-end 10mm loads (the Norma in particular) earned a reputation for beating 1911 style guns into the ground. Current 10mm loads are more modest, but until someone can explain how the dwell time can be adjusted on a short recoil system using a barrel link, I’ll go along with Tuner – who has forgot more about 1911 pistols then most people know. His experience parallels mine.
  17. Beagle-zebub

    Beagle-zebub Well-Known Member

    It makes sense that a gun with cam unlocking, like the 75, would have the potential to adjust for dwell time, but were there other features of the 75's design that the Bren Ten retained, and that added to its strength? It would lead me to think that if the 10mm Witness was properly engineered, it might also be that tough.

    Smiths are another possible lead.

    The people at 10mmTalk report that the OEM barrel of the Glock 20 (and 29, presumably) puts a "happy-face" mark on the brass of full-tilt 10mm loads, what with the less-than-ideally supportive chambers that Glocks have.

    I'd have to think that a factory 10mm XD would be popular--in the Tactical length, it would have the same 5" barrel of a Delta; its cam-unlocking could be better about this "dwell-time" of which the Fuffinator speak; the grip angle-angle manual safety appeal more to hardcore-but-conservative pistol shooters, who are many of the people who shoot 10mm; and XDs already have fully-supported chambers. There would still be the downsides of shooting 10mm in a pistol that light, and having a trigger that isn't a 1911's, but it doesn't seem to be hurting Glock too badly.
  18. 1911Tuner

    1911Tuner Moderator Emeritus

    Ya'll ain't payin' attention...

    Pressure isn't the only issue. Recoil force bangin' into the breechblock is.

    Bullet weight/mass...not diameter...is the killer. A 150-grain bullet at 1,000 fps is easier on the gun than a 250 grain bullet a 1,000 fps, assuming an equal rate of acceleration.

    What many people don't understand about recoil and velocity is that about 90% of both are generated within about a half-inch of bullet travel in the barrel for pistol cartridges. Depending on the powder burn rate, it can be less.

    Think of it like this...

    If we gain or lose 30 fps per inch of barrel gained or lost...and we have 1,000 fps at the muzzle of a 6-inch barrel...the barrel accounts for 180 fps of the total. Where does that other 820 fps come from?

    So, now, you're accelerating a 150-grain bullet versus a 250-grain bullet to 820 fps in a half-inch. Which one will generate the higher recoil force against the breechblock?

    We're not done...

    While the bullet is being slammed into the barrel under high frictional resistance, the barrel is being dragged forward. At the same time, the slide is pulling the barrel backward against this high drag force. The locking lugs are keeping the two from separating under shearing forces...with the front faces of the barrel lugs bearing against the rear faces of the slide's lugs.

    Now...Go look at the lugs in a 1911 pistol...at how small they are... and remember that all three may or may not be bearing equally. If the barrel is factory rather than being carefully hand-fitted...you may have only one or two lugs resisting that shearing force.

    Now is it starting to make sense?
  19. freakshow10mm

    freakshow10mm member

    Not much help (well actually that last pic isn't too bad) but I found the pics of the top end of the pistol I sold. I think I was getting close to 26,000 rounds or so.

  20. 1911Tuner

    1911Tuner Moderator Emeritus

    I see a bit of setback in the first and second barrel lugs. Might want to have a close look at the slide's lugs to see if there's a corresponding deformation on the rear faces.

    What we can't see is the stress occurring in the slide in the corner formed by the port and the breechface cartridge guides...at least not until it's too late.

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