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243,260 or grendel for ak

5K views 39 replies 12 participants last post by  1biggun 
#1 · (Edited)
Ok,
the grendel has a certain cool factor, but lets face it, it's a propritary round and there is no real supply of ammo. Plus no true ak series mag to make it work. (223 should do ok but no evidence)

The 260 is known for its long range power and accuracy
the 243 aint too bad either.

bullet weight muzzle e/v 400 yard e/v 400 drop 400 drift
762x39 123gr 1520/2350 533/1392 41.5 27.6
6.5 120gr 1693/2520 885/1822 37.3 ?
243 95gr 1930/3025 927/2096 20.4 14.8
260 120gr 2913/2950 1190/2113 20.8 13.4
308 150gr 2648/2820 1382/2037 22.7 13.7

Purpose of gun:
white tail at no more than 400 yards

I have plenty of m-14 mags so feeding a 260 or 243 is no problem.
There may be a problem with 6.5 mags.
Barrels are expensive for 6.5
Take off barrels are cheap for 243, and 308
Ammo is plentiful for all except the 6.5

So:

Does anyone know the base diameter of a remington 700 barrel if I spin off the threads? >>>found it, .992"<<<<

Anyone think the yugo trunnion and bolt wont last against the 243?

anyone have experience with bent metal or cold steel solutions yugo receivers?

anyone have a link to pressures for the 243?
 
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#3 ·
http://www.gunco.net/forums/f244/260-rem-ak-better-than-grendel-35106/

Been on my to do list for a while. the 260 will out perform the 6.5 grendal in every area except recoil and ammo weight. A remington 700 barrel will work the OD with threads is 26.90MM. I cant tell what it would be once threads turned off but it is bigger than the 23MM needed. I have several Remington and Savage take off barrels put away for such a build. I perfer the savage barrels as the breach/chamber is not recessed and I feel the savage stuff is more accurate. IMOA you might want to consider simply rebarreling a siaga 308. the mag an every thing else would likely work as is.
The 260 is loaded pretty hot 60,000 PSI+. However there are a lot of decent hand loads listed in the 50,000 PSI range or even less that will still out perform the 6.5 grendal by by wide margin. also consider the 7mm-08 this nis a good Whitetail round as well. If you are truely going to try to shoot 400 yards you better plan on a better scope mount(something mounted on the RSB not the reciver) and a lot better trigger. I shoot 400 yards with my 223 varmit AK and it aint easy to get one accurate out that far. a deer is a lot bigger than a praire dog but 400 is a long ways with out a lot of work on one of these.
 
#4 ·
Been thinking on the scope mount too, right now I have one lane that is 387 yards but the property past it (100 acres) just sold, I don't know what they are going to do with it (subdivide or horse farm) After that my longest lane is around 250 yards. Dunno, may do a sort of psl look alike in 243... Have a ar10 lower in aluminum I have been meaning to cut out, may use it for a nice range only 260 remington.
 
#5 ·
243 win = 60,000 PSI I bumped the chamber pressures thread up to this page would be nice if it was a sticky..
here is the scope mount I made for my 223. it is heavy though. Personaly if I was going to be hunting deer mainly I would stick with the 308. honestly how many time are you going to really be shooting 400 yards? I like the knock down power of a 30 cal plus it is going to be cheaper to shoot and that means more practice time and that is more important IMOA than what Calibur you are shooting. I wanted a 260 for trying to hit varmits at 500+ yards. There is also a 22-243 wild cat that I have been eyeballing think its the same as the Texas Trophy round. guys are shooting white tails at very long range (not a big .22 cal on dear fan myself) this uses a real fast twist barrel and 70-90 Grain .22 bullets. barrel life is very short however.

 
#6 ·
I'd tend to favor the 243. While a skosh bigger, my 6mm Remington vs 308 Win (and recently, Mosin/7.62x54r):

both give consistent, one-shot, quick kills on western whitetails. I've taken around 10 with the 6mm and ~15 with the 30 cal.

the 100 grain 6mm bullet is always in & out, as are the 30 cal. Exit wounds on the 6mm are 2-3x caliber, 30 cal exit wounds vary widely from caliber-sized to almost fist-sized. I've yet to find a brand of bullet that gives consistent expansion on whitetail in 30 cal.

less blood-shot meat with the 6mm pill.
 
#7 ·
This is my FrankenAK



CS Yugo Sheel, Modified M14 mag, PSL gas tube, M70 carrier/bolt, M70 trunnion, M70 gas block, CF whatever stock, Winchester take off barrel, Custom RSB, and Sagia forearm. It is still in the buildup/testing stage, so yes those are screws holding it together for now, rivets later, and the stock is not all the way in.

Here's the custom heavy gas piston next to a std one.



ETA: Oops it's .308. Hope this answers some of your questions.
 
#8 ·
I question the m70 trunnion and bolt longevity with 308, My line of thinking was the 243, while pressures are similar, would be less distructive on the bolt, don't have a reason merely intuition. I do have an fal 308 bbl sitting here but....

I also have way too many guns in 308 range and above.


Gunter how bout a pic of that modded m14 mag? Looks like the mag needs to go forward or the bolt extended.

(I still dream of the days of living in Colorado, prarie dog and mule deer hunting at nice long ranges, now I feel like I live in the thick, dirty flat lands and never see the sky <childhood remington 700 7mm mag just sits here>)
 
#9 ·
The bolt thrust would be the same for the 243,260,7mm-08 and the 308 if the chamber pressure was the same. The recoil on the on the other hand the stress that the reciver and stock would feel will vary as the bullet weights increse.

I killed my first deer with my grandmothers remington 244 pump. ( the original 6mm remington). and I have a lot of friends who hunt with a 243. I have killed most of my deer black tail mule and white tails with a win mod 70 in 30-06 with factory remington 150 grain core loks. 90% of the deer I have seen killed were with remington ammo in 30-06 or 7mm Mag. I honestly cant recall a properly place hit getting away. I now relize after taking up hand loading that there is a lot better stuff out there. 30 cal weapons like the 30-30, 308 30-06, have likely killed more deer than all the other caliburs combined.
I have a son that will be hunting in a few years and a light weight 243,6mm,260,7mm08, 7mm mauser and the 308 are all on my list of canidates for his first bolt action.
If i was hunting only muleys in open ground I would skip the smaller caliburs and get him a 7mag and let him start out with reduced recoil ammo.
 
#10 ·
It will be a few days before I can get some pics of the mag. Got to hit the road. Just a 1/8 inch piece of rod mig'ed to the front and cut to a lip, plus a tab mig'ed on the back and filled in. Feeds by hand and by spring. I still need to drill the gas hole so it will cycle.

The big things are shortening the trigger guard for the longer mag, moving the ejector back which requires the slot in the bolt to be made longer so the bolt can rotate home, getting the center support in the right spot so it clears the mag and the hammer spring, grinding a relief in said hammer to clear support, and making a RSB to fit over the big chamber area in front of the trunnion.

As far as it lasting....Don't know. The Saiga .308 only has the bulged trunnion on the right side (IIRC). I hope that if anything starts it will change the headspace which I check after a couple of shots. It's had 25 rounds through it so far checking feeding and nothing has changed yet. Plus I plan to handload plinking rounds and save the mil-spec stuff.

I guess I should change the other post. It's really 7.62 NATO that has been headspaced to SAAMI .308 specs.

My son uses a .243 and a couple of years ago popped a white tail at 277yds off our deck.
 
#11 ·
Don't worry too much for AK trunions handling the pressure - remember all those discussions about the .308 bolt vs. the 7.62x39 bolt, with comparison pics. If you use a bulged trunion Yugo kit as the start, it will have the same amount of metal as the 7.62x39 build. My Romy "G" kit build into .308 shows no signs of excessive wear.

Whatever you do, I'd recommend a .064" thick blank. Those .050" blanks may work as well, but you really want the extra metal to stiffen it up.
 
#12 ·
So if I wanted a .243 AK I could use a Yugo trunnion and cold Steel Solutions RPK receiver blank with the rest of a Romy kit, right?
 
#13 ·
possibly, the question is whether or not the 762 bolt can handle the higher pressures. The trunnion is the same (in the critical areas) as the 308 trunnion. The difference is the lugs on the bolt. The 308 bolt has the extractor area moved forward away from weakening the lugs.
pressure on the 308 and 243 is significantly higher than 762 plus the diameter of the base is larger (more area pushing against bolt)
 
#34 ·
possibly, the question is whether or not the 762 bolt can handle the higher pressures. The trunnion is the same (in the critical areas) as the 308 trunnion. The difference is the lugs on the bolt. The 308 bolt has the extractor area moved forward away from weakening the lugs.
pressure on the 308 and 243 is significantly higher than 762 plus the diameter of the base is larger (more area pushing against bolt)
we had a very similar debate on saiga-12.com, when some newb decided it was a good idea to grind off the "extra" 3rd lug on his saiga 308.

there is a very good reason whyt he ruskies decided it NEEDS a third lug and other design modifications.

If it was safe, don't you think they would have just left good enough alone, rather than spending all the time and money to redesign/retool?

I STRONGLY feel these mods are extreamly unsafe.

Remember that a lot of old british 303 rifles were changed to 308. and while the vast majority of them have not blown up YET (there have been some failures IIRC), it is an unsafe practice. Especialy since 308 ammo is loaded to higher presures than the military equivalant 7.62 x 51 NATO. The indian 308 rifles were built using stronger steel.

And 243 is just as high PSI as the 308. The PSI is higher than the 7.62x39, and the area (square inches) is also higher. thus producing much more stress on the lugs. You can do the math yourself, take the area (in square inches) (that's pie R squared) of the case head, and multiply it by the chamber pressure, you will get a MUCH HIGHER value for the 308 (and equivilants) vs the 7.62 x 39.

A bulged yugo trunion MAY be safe enough (I still wouldn't want to take that risk), but a normal romy g trunion is deffinitely not. I would be concerned with any 7.62 x 39 mods.


PLEASE BE SAFE, PEOPLE






I strongly believe the only safe conversion is the 308 saiga ---> 243 (etc)


which I am currently working on. :woot:
 
#14 ·
Well I bit the bullet and ordered 2 new factory Remington 700 take off barrels one in 243 and one in 308. Leaning towards the 243... But hey they were only $20 each new condition.

Should have them by the beginning of next week.
 
#19 ·
Ok, here's a pic of the mag top.



And a blurry one of it feeding. Round is started in the chamber and still held by the mag lip. Round pops out just before shoulder hits the trunnion side. (Sorry for it being the long way. Everytime I rotated the pic it would cut it off.)
 
#23 · (Edited)
From looking at things, the 6 PPC would work pretty good with a barrel change. You could likely use the stock magazines as OAL for both cartridges is approx 2.19in. It's doubtful that you'll be able to load up 30 cartridges tho. Modifications to the bolt and maybe the ejector would be all that is needed.
Add a 24 inch barrel and you have a poor man's PSL.
 
#24 ·
the 6mm ppc is doable. the stock mag likely will not work as the ppc round does not have the taper. a straighter 223 mag with a 7.62 follower might work as well. I have a 243 barrel I was considering rechmbering for the ppc awhile back then I got side tracked . Ammo is really pricey. I have heard of guys forming it from 7.62x39 but it reguires some expensive forming dies. A no neck turn/looser chamber would be likely the way to go. feeding the ppc is said to be tempermental in a auto loader due lack of taper and the neck angle but the round is very close to the grendal and there are 6mm PPC th AR uppers that do it as well.
the 220 russian is another one that would likely be just a barrel change but $$$$ to shoot
 
#27 ·
the 6mm ppc is doable. the stock mag likely will not work as the ppc round does not have the taper. a straighter 223 mag with a 7.62 follower might work as well. I have a 243 barrel I was considering rechmbering for the ppc awhile back then I got side tracked . Ammo is really pricey. I have heard of guys forming it from 7.62x39 but it reguires some expensive forming dies. A no neck turn/looser chamber would be likely the way to go. feeding the ppc is said to be tempermental in a auto loader due lack of taper and the neck angle but the round is very close to the grendal and there are 6mm PPC th AR uppers that do it as well.
the 220 russian is another one that would likely be just a barrel change but $$$$ to shoot
Wondered if a lack of taper would make a big difference. I also saw the chambering with the ARs in 6 PPC. Figured if they could get the AR to feed the 6PPC, an AK should be doable. IIRC the no neck turn case is sold by Sako and called the 6PPC USA.

Found a source for the brass-19.95 per box of 20 casings tho.
Item Details

Here's a link to 6PPC cartridges and cases.
Sako Ammo & Brass, Lazzeroni

Here's a site with cartridge diagrams and info on the 6PPC.
6PPC Cartridge Guide
Cartridge Diagrams

Here's Lapua Russian 220 brass.
Lapua 220 Russian Brass for Reloading 100

Midsouth?LAPUA AMMUNITION & COMPONENTS?220 RUSSIAN BRASS 100RDS
 
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