Recoil spring quandary

Discussion in 'Black Rifle Forum' started by adamg01, Feb 8, 2020.

  1. adamg01

    adamg01

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    I have a DD AR15 and I recently bought a 450 bm upper to have a hunting setup this coming deer season.

    My question is if I buy a heavier recoil spring to make sure I can send home the bolt on a full 450 mag will it cause any issues to use the same recoil sprout
     
  2. dkf

    dkf

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    You should not need a heavier buffer spring for the .450bm to begin with.
     
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  3. faawrenchbndr

    faawrenchbndr CLM

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    Standard buffer is a good place to start. I prefer the A5 buffer system, allows for more adjustability. I like to use a Sprinco green spring
     
  4. adamg01

    adamg01

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    It would be nice if I didn’t. It can’t even close the bolt on a full mag of 450 ammo. Apparently this is common and I’m
    Not surprised. The bullet is more than twice the size of a .223 plus it’s straight walled.
     
  5. adamg01

    adamg01

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    The standard isn’t sending the 450 fully into battery. I’m just wondering if the heavier buffer spring will be ok to use on my 5.56 upper too or will I have to change the spring each time I change the upper?
     
  6. dkf

    dkf

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    I have a .458socom rifle using the standard carbine spring. The .458 is not straight walled but it is bigger and uses bullets much heavier than the .450 does. Size and weight has little to do with it.

    The first round not going into battery with the .450 is usually a magazine issue. The extra spring pressure from fully loaded mags causes the round to ride higher and more nose up causing more resistance to go into the chamber. The subsequent rounds have less spring pressure on them and do not ride as high or as nose up. The extra power buffer spring is a bandaid. Even the Bushmaster mags have problems. A common remedy is to shorten the magazine spring some and/or tweaking the feed lips on the mag and even polishing them. Tromix offers a center feed follower for Lancer magazines which can help.
     
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  7. adamg01

    adamg01

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    Ye
    Yes these are new BM mags by the way.
     
  8. cciman

    cciman

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    Why do you need a full mag to hunt deer?
    Will it function normally on partial mags?

    I agree with above that it is not a buffer spring issue.
     
  9. adamg01

    adamg01

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    Well it’s a 5rd mag. I’m definitely not going after them with 20rds.
     
  10. Z71bill

    Z71bill

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    How many rounds on the old spring?

    Maybe a new one would function -
     
  11. adamg01

    adamg01

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    Probably roughly 300rds of 5.56 on it. I was reading on the 450 forum that this is a common issue and the easiest way to tell is to load up a few 450 mags, release the bolt and see if it goes fully into battery. I have two mags and neither would go fully into battery.

    I ordered a heavier spring for Grendels and 450’s, I’m mainly just wondering if the heavier spring would be ok to use with my 5.56 upper too. It’s going to be predominantly for hunting with the 450
    upper and the 5.56 upper won’t be used much.
     
  12. Tbags

    Tbags

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    Grendel's don't require a heavier spring to function, nope not at all. A heavier spring should work with you 5.56, may also cause it to short stroke but the good thing is a spring change takes about 1 minute or less to swap out.

    This really sounds like it's a more of mag issue than spring issue.
     
  13. adamg01

    adamg01

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    I’m not saying you are right or wrong. It very well could be a mag issue but at the same time it’s two different brands of mags that have the correct 450 follower. Neither will go into battery. I got a heavier spring and the issue was solved. The more I researched it from people doing 450 builds this isn’t uncommon.

    I just hope my 5.56 upper can handle the heavier spring. This isn’t a big issue either way. It’s going to be my hunting rifle so I didn’t want to have to modify my new 450 mags when I can just get a heavier spring more suited for the larger caliber.
     
  14. dkf

    dkf

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    No question it is a magazine issue, a well documented one. The follower is not the main culprit either.
     
    Last edited: Feb 17, 2020 at 9:28 PM
  15. faawrenchbndr

    faawrenchbndr CLM

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    Buffer and spring selection really depends on barrel selection and how it’s gassed.
    Most quality makers have the port sized for standard buffers and springs.