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Thread: 260 REM AK Better than a Grendel

  1. #11
    Gunco Member Hawkeye Mole's Avatar
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    These are the rounds I'm kicking around for AR15/AR10 type weapons:

    Round, Platform, Use, and Optimal Distance

    Short Range
    .338 Spectre, AR15, Tactical entry round with lote of punch, Under 50m
    .50 Beowulf, AR15, Great penetration and knockdown power, Under 200m
    450 Bushmstr, AR15, Heavy hitter, Under 200m

    Medium Range
    6.8x43mm, AR15, Excellent assault rifle cartridge, 300m+

    Long Range
    .260 Rem, AR10, Magnum performance, same length as .308, 600+m
    6.5 Grendel, AR15, Extreme long range, great terminal balistics, 1200m+

    While trying to minimize the number of different calibers I deal with, I'm still open to new ideas. I guess the question of .260 being better than a 6.5 grendel for your uses is whether you want to fire from an AR15 or AR10 type weapon.

  2. #12
    tired of idiots vz58's Avatar
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    I am still hesitant to put a 308 family round into an ak bolt and trunnion. I know it has been done, but how many rounds have been shot? Anyone care to comment I would like to listen.

    I would have built my 45 win mag in 450 bushmaster had the round been out. I may still do it but question my thompson barrel being adequate to the task.

  3. #13
    No Hope For Me 1biggun's Avatar
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    I guess the question of .260 being better than a 6.5 grendel for your uses is whether you want to fire from an AR15 or AR10 type weapon.
    Not so much a question put a statement. The fact that a longer round can be utilized is an advantag a AK has over the AR15 IMOA. the 260 hands down out perfoms the Grendal in every way except weight of packing large amounts of ammo. and that is minimual.

    am still hesitant to put a 308 family round into an ak bolt and trunnion. I know it has been done, but how many rounds have been shot? Anyone care to comment I would like to listen.
    A 260 or any other simular sized bolt faced round loaded at 48,000-50,000 is going to have the same or very close BOlt thrust as the comercial and puplished hand loads for the 7.62x39. and in the case of the 260,243 it will have less recoil (stress on the reciver ) when used with lighter bullets like the 85 GR. stuff as there is less recoil. I am not saying build a 308 and load it to 61,000 PSI however there is simular AK models that will handel just that. M76 and M77 for example. I have yet to hear of a AK failure with any load. Not sayng it wont but unlike the AR 15 that crack bolts the AK dosent seem to have that reputaton.

  4. #14
    Happy Camper hcpookie's Avatar
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    Maybe we should post those pressures. I know they were all "around" 50,000 cup but I need to dig those back up. VZ, I understand your concern because my bullpup .308 conversion of a 7.62x39 platform puts the chamer RIGHT IN FRONT of my nose. So if anyone should be concerned about .308 pressures, it would be me.

    That said, I am confident that based on the existing .308 design and the close chamber pressures between the two rounds, I am confident it will not cause me problems. If it would, it would have most certainly have done it within the first couple of rounds. You may recall that the gas block I reamed failed on the first round and the replacement that I reinforced with a thick weld bead has held up perfectly.

    So FWIW, I think it is a matter of comparing apples-to-apples chamber pressures and working from that data. If pressure is a major concern for a very hot round, I think something like a .30-06 or 8mm platform would be my starting point, irregardless of cost.

    If I can find some CUP data I'll post it elsewhere.
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  5. #15
    No Hope For Me 1biggun's Avatar
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    Hc the the 260 is is a very modern round standardised in 1997 most modern rounds will only have champer pressures listed in PSI. the hotest load in my lyman book for it is is 59,700 PSI that is a Max load and it is pretty hot it is likely way over a factory round. the starting load for that same powder is 43,400 PSI that is way below the 7.62x39 round. I feel that some were in the middle is a safe and very efective round load for the AK. the hotest load for the 7.62x39 is 44,700 CUP in that same book. keep in mind that CUP is measured differantly than PSI and roughly comes out to 4000 to 8000 PSI under an identical round measured in PSI. SO one can assume IMOA that the hotter factory/military loads for the AK are aproximently 49,000- 50,000 PSI.

    HC your 308 If it were loaded to the max (compressed charge) with winchester 748 powder (the factory recomended powder) it would make 41,600 CUP that is 51.2 grains powder and a 125 grain bullet and the velocity would be aprox 3034 FPS. that load has the less chamber pressure than any of the max lods listed for the 7.62x39 123 gr loads listed.(43,000 was the lightest max load) this is about as apples to apples as you can get. by the way that 308 load I listed is about 600 FPS faster than the AK round a HUGE IMPROVEMENT WITH LESS CHAMBER PRESSURE!!! The same can be done with the other 308 family of rounds there are 7mm-08 loads that only make 45,000 CUP in the books as well. one can closly compare the 260 and the 7mm-08 with same weight bullets to get a rough idea what the 260 CUP presures may be.

  6. #16
    No Hope For Me 1biggun's Avatar
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    well I have a pair of stainless sporting weight 260 Remington barrels coming. should be here in a week. Im going to build a 260 on a yugo trunion and likely a opened up 5.45 bolt if I can find one cheap. Im thinking of sleaving it for a big stem carrier and then I can tighten up the clearances while Im at it.

    I have some ideas but havent completly thought it all out. Im doing several 308 length builds and Id like to sort of standerize my builds. I have also been giving a lot of consideration to a switch barrel set up were I thread the trunion and screw in the barrel. Its been done before. that way i can have a 22-250, 243, 308 ect even a 410 SG possably on the same reciver. its getting pretty pricey building a new gun for each calibur. I have a super light weight sporter build staring as well for my son in 243 that Im trying to get the weight down to a bare minimum. I will still use a yugo trunion however.

    I think I have a way to utilize the g3 mags and on the 260 I am going to lengthen them sligtly to use fully seated 142GR bullets. the AR10s cant do this. the 260 is a high pressure round and factory loads can be at 60,000 PSI. I will not be using factory loads. i am going to stay under 50,000 PSI. Ill still be able to out do the 65 grendel with these loads and be able to launch the heavy bullets better.

  7. #17
    No Hope For Me 1biggun's Avatar
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    barrels are here there very light weight of a model 7 remington there lighter than a standard M700 barrel the good news is I can go several ways on the GB and I will not have to do much lathe work.

    Any thoughts on how far you can put the GB on a 50,000 PSI round and not have timing issues?? id love to put a adjustable F1A1 block way back. I got two barrel to play with one may go on the Saiga 308 convserison If I can pull of the switch barrel build. the other on my sons hunting build still need a cheap ak74 bolt.
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  8. #18
    tired of idiots vz58's Avatar
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    Biggun talk about a thread from the past.


    I would go small on the gas port. small enough that it may not cycle.

    I would be done on the 45wm if I had gone small.

    BTW did I mention go small?

    you can always drill larger...

    but only if you go....well you get the idea

  9. #19
    No Hope For Me 1biggun's Avatar
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    Im more worried about premature bolt unlocking if I move the GB back to far. I like the idea of a very short pistion on a rifle but Im a little leary of port timing issues. Im working on a youth build were balance of the rifle and weight is important. a small 10 year old will have to hold this up so any weight I can get off the front of the rifle the better. besides witha L1A1 GB ill be able to drill over size and adjust the gas as well as shut it off. this is not a high accuracy build so i can live with a port. i want to be able to cycle reduced loads so its tame for a kid to shoot. Im guessing a .080 port would cycle it maybe a little bigger to deal with the increased mag pressure and drag from the longer rounds. My 223 cycles with .080 at 55,000 PSI. seems like we decided years ago in my 223 with a 26 inch barrel that the bullet was long gone at any distance but the AR,s sure seem to be sensitive to port timing and I wonder why.

    Has any one built a short piston long barrel rifle?????? I can always sleave the GB but it would look cool with a shorter gas tube as well. Im betting they made them a certain length for a reason.

    Ive wanted a 260 for a while and I came across these barrels there to thin for serious varmit work but the round will still reach out and touch something at 1000 yards. this is likely going to be part of my switch barrel project. If I do it on a switch barrel trunion I can just take a old crap .30cal barrel and try a super short piston and it wont cost any thing if it fails unless the gun blows up and the bolt comes out the back of the reciver. :I

  10. #20
    Gunco Regular droog's Avatar
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    I built Fal with a 5 1/2 in. gas tube a d had zero problems.
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