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Thread: Bolt life question.

  1. #121
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    Re: temperature-- the bolt lug difference between piston and Di is about 40*f. The bolt body, around 100*f. Now, this temperature cycle fatiguing the bolt, would it not be much worse if another 50*f were stacked in? Would it then not be logical that an m4 shot in the winter would break the bolt at a different rate by a very noticeable amount of rounds than one shot in the heat of the summer? I just can't believe such a differsnce is measurable.

    Re: qpq-- I had the slide on my stainless Sig qpq treated. I also have a stainless Sig that was not. The one that does not, shows self limited peening where the barrel hood impacts the locking interface of the slide, fore of the chamber. The qpq weapon was fired a few hundred times, then sent to be treated. Upon return, and firing it, I note fine chips instead of peebing of the slide. The barrel lug on the other hand, I have to inspect again, but it seems much more suitable. I would not qpq things blindly and expect positive returns in all cases.

  2. #122
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    Quote Originally Posted by WS6 View Post
    Re: temperature-- the bolt lug difference between piston and Di is about 40*f. The bolt body, around 100*f. Now, this temperature cycle fatiguing the bolt, would it not be much worse if another 50*f were stacked in? Would it then not be logical that an m4 shot in the winter would break the bolt at a different rate by a very noticeable amount of rounds than one shot in the heat of the summer? I just can't believe such a differsnce is measurable.

    Re: qpq-- I had the slide on my stainless Sig qpq treated. I also have a stainless Sig that was not. The one that does not, shows self limited peening where the barrel hood impacts the locking interface of the slide, fore of the chamber. The qpq weapon was fired a few hundred times, then sent to be treated. Upon return, and firing it, I note fine chips instead of peebing of the slide. The barrel lug on the other hand, I have to inspect again, but it seems much more suitable. I would not qpq things blindly and expect positive returns in all cases.
    Excellent point, if the extra heat from DI is what killed the bolt, then rifles used in very cold places would have incredibly shorter lifes than ones used in warmer temps. Since the heating/cooling cycle would be far greater.
    Quote Originally Posted by C4IGrant View Post
    Colt builds War Horses, not show ponies.
    Quote Originally Posted by Iraqgunz View Post
    This is 2012. The world is going to end this December and people are still trying to debate the merits of piece of shit, cost cutting crap AR's. Really?

  3. #123
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    On the cold temp issue, the HK416 initially had problems in nordic conditions. I wonder if that was a bolt issue.

  4. #124
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    What problems was the HK having in "nordic" conditions?
    Last edited by Arctic1; 08-19-12 at 19:38.
    It's not about surviving, it's about winning!

  5. #125
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    Quote Originally Posted by MegademiC View Post
    For the stag thing, I've understood it as stag is CMT's storefront brand. I bought one a couple years ago(before I knew better). It has the 4140 barrel, untested barrel and bolt etc... however, I've had about 5k through it without a single malf. Its not a high round count - and is not to the specs of colt/noveske/bcm/dd etc, but for a "midgrade" ar, id say stag and SW are the 2 best of that group (I paid $750 otd). In fact, I've only seen 2 complaints/problems about stag and one was a rediculous round count - guy claimed thousandssSSS of rounds per month. All that said, Im having a top-grade gun put togethe once I get the funds.
    Stag Arms parts are the equal in real quality to say, Colt or BCM, and better than most. For complete rifles, the 4140 1/9 Chrome Lined compares to well to other 1/9 4140 barrels, and cost less than the 4150 1/7. I personally own both with plenty down the pipes. Because they market a rifle with a 4140 barrel option, doesn't a bad manufacturer make. Lots of people are well served with a 1/9, and theirs (mine) measures out to 1/8.25", which has no issues with 1/7, regardless of conditions. When I burst a semi-auto barrel I'll let you know. Most of my guns are 1/7 4150 though, just because.

    For the bolt stuff, the LMT bolts in theory should be better with the radiused lugs(where they come out of the bolt). This distributes the stress.

    Heat has been shown to be a non issue. Also, on TOS I think they had numbers posted - the carbine gas on a 16" barrel(maybe a 14.5") caused unlocking before the barrel depressurized down to the piston camber pressure levels. In midlengths, it was later reducing a lot of pressure from the lugs.

    For the cam pin hole, I would think that a midleth would help in 2 areas. 1- slightly slower cycling which means less stress. 2 - less pressure on bolt from the barrel gas, reducing friction on the lugs, which would reduce stress on the campin hole.

    These are just intuitive and not tested by me. Its hard to test since most large organizations use carbine gas.
    All interesting in theory, but when a rifle has to work in 'adverse', the carbine length will go bang for longer with a wider variety of ammo. As one national armorer employee remarked on the request, 'but carbine length works!'.

    The comparison might = searching for flysh!t in pepper however. They both work well for the vast majority of users.

    For myself, carbine length gas + a matched buffer for the stock of ammo. If a carbine runs a H2 with M855, do it. Definitely for MK262. If you've got a flat of Rem white box 223R1, maybe take it down a notch to the H1 or Standard, as works. A H will run everything smoothly but the 77gn high pressure cartridges, which deserve a H2.
    Last edited by dangertree; 08-19-12 at 21:59.

  6. #126
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    Quote Originally Posted by dangertree View Post
    Stag Arms parts are the equal in real quality to say, Colt or BCM, and better than most. For complete rifles, the 4140 1/9 Chrome Lined compares to well to other 1/9 4140 barrels, and cost less than the 4150 1/7. I personally own both with plenty down the pipes. Because they market a rifle with a 4140 barrel option, doesn't a bad manufacturer make. Lots of people are well served with a 1/9, and theirs (mine) measures out to 1/8.25", which has no issues with 1/7, regardless of conditions. When I burst a semi-auto barrel I'll let you know. Most of my guns are 1/7 4150 though, just because.

    I'm going to have to ask you to provide documentation supporting this statement.



    Quote Originally Posted by dangertree View Post
    All interesting in theory, but when a rifle has to work in 'adverse', the carbine length will go bang for longer with a wider variety of ammo. As one national armorer employee remarked on the request, 'but carbine length works!'.

    I'm going to have to ask you to provide documentation supporting this statement.

    Further, you are simply assuming that the increased friction from the buildup of 'crud' is the reason that a rifle may not 'work' in an adverse condition. I run rifles with the BCG's bearing surfaces polished to a shine and dripping with quality lube (Slip 2k EWL)....friction is not an issue for me even after thousands of rounds with no cleaning.

    Acknowledging that overcoming friction is not a primary factor in reliability, the 16" carbine gas system has only liabilities in its corner. I think that you have not taken into account the greatly increased gas port pressure (and correlating increased stresses on the bolt, cam pin, and extractor) in a 16" carbine gas system vice a 16" mid length gas system. Add to that the increase in dwell time (time system is under gas pressure) and you have a compounding of issues that ALL work to only degrade bolt life and extractor performance at an accelerated rate over the 16" midlength gas system. Pat Rogers put over 46,000 rounds through his "Filthy 14" BCM 16" mid-length before retiring it....under a rigorous class schedule, to boot. You show me a 16" carbine-gas Stag/CMT gun that has done that, and we can begin to have a factual conversation about this topic.
    Last edited by BufordTJustice; 08-20-12 at 04:33.

  7. #127
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    Quote Originally Posted by dangertree View Post
    Stag Arms parts are the equal in real quality to say, Colt or BCM, and better than most...
    Stag bolt cam pin after less than 500 rounds fired. This is the third Stag cam pin I know of that has cracked like this after less than 1000 rounds fired. Equal my a**!


  8. #128
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    Quote Originally Posted by Arctic1 View Post
    What problems was the HK having in "nordic" conditions?
    You do not know? It was all over The Internet that HK does not work in Norway*. Have you ever been in Norway? This is one hell of cold country you know!

    * for some one particular poor SOB with Internet access.
    Montrala

    I'm sponsored competition shooter representing Heckler&Koch, Kahles, Hornady and Typhoon Defence brands in Poland, so I can be biased

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  9. #129
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    Since Arctic1 has some personal experience of the HK in not only Nordic, but Norwegian climate I guess he was wondering what the rumour mill had cooked up this time.

  10. #130
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    Quote Originally Posted by skullworks View Post
    Since Arctic1 has some personal experience of the HK in not only Nordic, but Norwegian climate I guess he was wondering what the rumour mill had cooked up this time.
    It's probably that one report from the guy who had a bad experience, certainly doesn't mean everyone had the same as him. From what I can remember it is the equivelant to our 507th maint.
    Last edited by sinlessorrow; 08-20-12 at 08:12.
    Quote Originally Posted by C4IGrant View Post
    Colt builds War Horses, not show ponies.
    Quote Originally Posted by Iraqgunz View Post
    This is 2012. The world is going to end this December and people are still trying to debate the merits of piece of shit, cost cutting crap AR's. Really?

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