ideal rate of twist (MLP firearms and shooting thread)

Discussion in 'The Backstage' started by JMV, May 28, 2010.

  1. smk506

    smk506 Senior Member

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    Lt. IT sounds like you may have a gas problem :eek2: http://farm7.staticflickr.com/6214/6335853733_1945959e27_z.jpg

    Can you reference the chart here and estimate where your brass is heading?

    Too, there is a special tool for sorting out feed lips on these magazines if you haven't chucked the old one yet. You may be able to get some more life out of that one as a range only mag.

    There are a few styles out there so you'll have to google it to see if one might work better than the others for you.
     
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  2. Kris Ford

    Kris Ford Senior Member

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    My Grampaw was one of the most important people in my life...so I know how the lil guy feels. :) He's been gone since '09, and I miss him very much.

    Oh, '69 Roadrunner is my dream car!! Grampaw had one of those as well. 383 4bbl 4 speed, red with black vinyl top, and black hood stripes.
    Bought new in '69, stolen from Wixom Assembly plant in '71..
     
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  3. SteveC

    SteveC Village Elder V.I.P. Member

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    What concerns me the most here are the failures to EXTRACT. Gas could very well be your problem. Where does your brass land (on the above chart)?

    Besides that as the cause, when did the failures happen? Beginning of the session? Or, after dumping several mags (hot weapon)? Long shot - no pun - but you could have a chamber tolerance issue.

    People might shit over this comment... "Throw that junk out and get some good ol' Magpul Gen 3 mags!"
     
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  4. Frogfur

    Frogfur Senior Member

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    Dave, there are several different issues it sounds like. 506 is correct in that there is a tool that can straighten and correct mag feed lips. But i wish when recommendations are made they would provide a link to the tool.

    Problems such as these are very hard to figure out without having it on the bench but here are some suggestions.
    1. Double feeds are almost always a magazine problem.

    2. If you have a tightly loaded 30 round magazine and your buffer spring is not as strong as you think it is to push the round all the way into the chamber you end up with a round half way out of the
    magazine. Now the bolt is not far enough along to use your forward assist to complete the cycle. Don't load your 30 round mags full. Load 28-29 rounds then you won't need to figure out a double feed to start.

    3. If you have issues with failure to feed that will be a mag problem. Try another magazine. The proper loading of magazines is an art unto itself, you know that. If the mag spring is unusually tight, and or strong which could cause a round to jump into the chamber prematurely causing a jam.
    Forward pressure on magazines(the way shooters hold a mag)can at times cause failures. Good shooters i see use the tap and tug method on loaded mags as a matter of habit.

    4. Disassemble, clean and check all mags and mag springs for damage and or dents to make sure ammo can move freely in the mags. A weak spring(s)is certainly possible when we speak of loading malfunctions.

    5. Assuming mags are not your problem, next is the buffer spring dave. A damaged, worn or broken buffer spring. This will be an issue. Most original buffer springs are not the quality of after market springs like those made by Spike and others. It's possible part of not all your trouble is in there.

    6. Failures to feed can also be caused by dirt debris and fouling=short stroke. Accumulation of fouling that are a by product of firing the rifle itself can cause a failure to feed malfunction of the bolt carrier group causing it to not cycle completely reward. Likewuse dirt and debris on the lower reciever extension buffer tube or a fouled gas tube can also gave a negative impact on performance. I do not suspect that as the problem yet. Lets work thru these first.

    let me know where you are at and we can continue evaluation.
    Next we will pull the barrel and or gas tube and see about cleaning that if necessary. But I don't believe you need that yet. And actually you may not have to pull the barrel, but it might not hurt either. I wouldn't hesitate if further inspection was warranted. Routine.
    The thing I would be taking a close look at with the barrel off would be a rough chamber.
    That could cause extraction issues even if Superman were trying to get that brass out.
    Are those old, used military mags you have ?

    Magazine feed lip repair tool-
    http://www.brownells.com/gunsmith-t...-15-m16-magazine-feed-lip-tool-prod21511.aspx
    How to use it-


    Uncle Dave's design, Function and diagnose
    AR-15 3 part Clinic-

    The doctor is in!


    Pt. 2-


    Pt. 3 Here's the Beef-


    This should help.





    Order a Brownells catalog of gun tools and parts. You will need one later on.
     
    Last edited: Aug 27, 2017
  5. Frogfur

    Frogfur Senior Member

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    Hey! Lol.. i use those too but your more than likely right. Very well could be mags.
     
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  6. Hairless_Ape

    Hairless_Ape Doc Premium Member

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    I can second the concealment express holsters. I have one for my G26. It's the only simple kydex holster I've bought that didn't have sharp bottom edges out of the package, and its got just the right amount of tension. Got my from Amazon, shocking, I know.
     
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  7. Hairless_Ape

    Hairless_Ape Doc Premium Member

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    I know your a 100 yd zero guy, Rob. But, if you zero the EoTech at 50, the bottom edge of the 68 MOA ring will be zeroed at 7 yds.
     
  8. bulletproof

    bulletproof aka tarddoggy Premium Member V.I.P. Member

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    Lt.,Im gonna second this....sounds to me like the mags as well. And like Larry said,after the mags are eliminated,on to the buffer spring. Bad spring can cause all sort of mischief with an otherwise well functioning weapon. In addition,I have to go with Steve on the Magpul.

    I have a bunch of Brownells standard GI type mags as well,but,the Magpuls,Sir,they just cant be beat for the durability and performance.After getting my first dozen,I went through all of my mags and ended up getting rid of more than half. I sincerly wish I had access to these during service time,no wonder the boys all rave about them. And to top it all off,they are a breeze to disassemble and clean.

    https://www.magpul.com/products/pmag-30-ar-m4-gen-m3
     
  9. Frogfur

    Frogfur Senior Member

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    That's why I always stencil my mags with numbers so I can identify them. The problem with Colorado is mag limits. No one will ship a 30 round mag here knowing that. Lucky for me I had a boat load of 30s and 20 rounders. I actually prefer the 20 round mags.
     
  10. Frogfur

    Frogfur Senior Member

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    Myself, I pretty much aim for just below the hair line. That should create a third eye.
     
  11. bulletproof

    bulletproof aka tarddoggy Premium Member V.I.P. Member

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  12. Frogfur

    Frogfur Senior Member

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    10 yard zero..much easier and quicker then confirm at 50 yards. I have found this the fastest and easiest way to zero my rifle. I can see target impact @10 yards! Even with my old eyes. Adjustments with EoTech and irons, red dots etc fast as a Wolverine on a waffle. Now, if you want to go beyond 50 that great. For me I want to point shoot hit him before he can return fire at 50 or, preferably closer. Fast accurate and violent.
    Because that is exactly what they will do to you given half a chance.
     
  13. Frogfur

    Frogfur Senior Member

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  14. bulletproof

    bulletproof aka tarddoggy Premium Member V.I.P. Member

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    Damn,that sucks,brother.....well,if you ever visit out here in my neck of the woods,I'll send ya home with souvenirs :yesway:
     
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  15. Hairless_Ape

    Hairless_Ape Doc Premium Member

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    I can mod some and send them to you frog. I buy 15/20 round limiters from magblock.com, then drive to DE and buy the 20 rounders. I install the blocks and epoxy the floor plates right there in the parking lot before driving home, so no laws are broken.
     
  16. bulletproof

    bulletproof aka tarddoggy Premium Member V.I.P. Member

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    Thats brilliant :dude:
     
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  17. Frogfur

    Frogfur Senior Member

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    You can get 15 round mags max.
     
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  18. LtDave32

    LtDave32 Desert Star Guitars Super Mod Premium Member MLP Vendor

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    Well fellas, this old soldier knows not to load 30 round mags all the way up. I load them to 29 rounds.

    But, that's not the issue, for I'll get a problem after 3 rounds, maybe.. After 5, after 10. Who knows.

    My brass lands according to that chart at consistently between "2:00, 2:30 and 3:00". So maybe I've got a $hit buffer and spring. This was a parts gun, assembled sometime in the late 1980's/ early '90's, and not by me. To demonstrate its age, the castle nut is of the smooth ring variety and held with an allen set screw. I can't even find such a castle nut anywhere. All of them today are of the "four notch" variety and tightened with an armorer's tool.

    So, once I was watching that reality TV show about a specialty gun shop in Louisiana. You guys may remember the show. A similar problem cropped up with a customer's rifle, and the old man what owned the shop mentioned that it might be the recoil buffer and spring being the wrong one.

    A correct recoil buffer and spring will give me the correct brass eject pattern, as according to that pie chart, yes?

    I don't think that an adjustable gas block up front is the answer. This weapon should run on the parts designed for it. Everyone else's does, why not mine?

    So let's hear about the different recoil buffers and springs; different applications for different stocks, right ones, wrong ones, etc.

    It seems to be the "last frontier" of this rifle.

    Remember, the unextracted brass literally falls out of the chamber when clearing the weapon. It doesn't hang up in the chamber. And I've had good success before. It just doesn't seem consistent enough to be a chamber issue.
     
  19. LtDave32

    LtDave32 Desert Star Guitars Super Mod Premium Member MLP Vendor

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    BTW, Froggy, Steve and all:

    Before, any problems I had happened after the weapon was hot. And on a really hot day.

    Yesterday, they happened right off the bat. At 0900, while it was still relatively cool out.

    I'm headed out right now (0900) to check it again, put a mag through it. I'll let you know the results and particulars.
     
  20. SteveC

    SteveC Village Elder V.I.P. Member

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    I use an adjustable gas block on my rile, so that I can "tune" the buffer/spring combination. I want to run just enough gas to cycle the weapon, with the least amount of recoil caused by bolt slamming into buffer/spring. I want the bolt to go back just far enough to make the exchange between spent and new cartridge - without bottoming out.

    Of course, my rifle would work properly with the stock gas & buffer/spring. But....

    Remember, for me this is NOT a SHTF weapon. It's a competition rifle and I need to produce fast follow up shots - ideally on target :) Anything that I can do to reduce muzzle flip and recoil gives me an advantage.

    There is some science to this, that the more qualified will no doubt explain better than I could. I cannot even remember what my buffer/spring combo is - LOL.

    But, it does cycle smoothly :)
     

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