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Old September 1, 2012, 09:47 PM   #1
jason41987
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7.62x39 necked down or 6.5 grendel

everyone says the grendel is merely a necked down 7.62x39mm.. however, it is not, it has much less of a taper, most like to work better in AR15 actions... is this really the only reason they created the 6.5 grendel rather than necked down a 7.62x39... for AR15 compatibility?... does anyone even make a wildcat reamer for 7.62x39 necked down to 6.5?
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Old September 1, 2012, 11:11 PM   #2
big al hunter
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I'm not sure about the grendel, but i load for my 7-30 waters. It is the 30-30 necked down and the taper is reduced and the shoulder moved forward by fire forming. The case dimensions are very different. I make my cases out of 30-30 brass. The case head is the only thing that stays unchanged. Many cartridges were born this way. Almost all of ( maybe all of ) the Weatherby cartridges started as something else. Wouldn't surprise me a bit if the grendel was originally a 7.62 first.
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Old September 1, 2012, 11:17 PM   #3
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well the .220 russian was a 7.62x39 necked down to .22 caliber, the grendel was based on this .220 russian but made to have very, very little taper, because as you know, in an AR15 the straight magwell requires little or no taper to function reliably... but a straight tapered case doesnt seem to feed as reliably as one that has more of a taper to it, like the untouched 7.62x39

so if instead of going with the grendel, you necked down the x39 youd most likely get better performance in every other rifle but the AR15
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Old September 1, 2012, 11:42 PM   #4
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Ah I see you are questioning the thinking behind the design. Straight case allows more case capacity and better velocity possibilities. Shoulder angle changes can make it inherently more accurate. But you never know until you try. Check midway and brownells, not sure if either sells reamers but thats were I would start. Or your local gunsmith. P.S. what are you going to rechamber.
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Old September 2, 2012, 09:26 AM   #5
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doesnt it just make sense for all the x39 rifles on the market to use a necked down version of the 7.62x39 case with its original taper so it could easily and freely use all the magazines out there?... with the neck not being as far back as on something like the grendel, you get atleast as much case capacity, better feeding, and youre still able to use those 123 grain 6.5mm bullets everyone loves (this is just an example)... the only one thats left out are the AR15 fanboys
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Old September 2, 2012, 10:18 AM   #6
big al hunter
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I did not realize that there was such a big feeding issue with our current military primary service rifle design.
Is it worth the expense to rebarrel an ak47 to shoot 123 grain bullets rather than the 124 grain load in 7.62? Or are you thinking about a different platform? I guess I am a little confused as to what made you want to try this.
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Old September 2, 2012, 01:33 PM   #7
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LOOK INTO THE 20, 22, 6MM, 6,5 BEGGS ROUNDS THERE BASICALY 220 RUSSIAN BRASS WITH A VERY VERY MILD CHANGE TO THE SHOULDER

The 6.5x39 has been done on 7.62x39 brass, 220 russian brass an there are also 6.5 bench rest rounds as well as necked down 308x1.5 Barnes that are basicaly cut down 308 win brass.

MY advice is try taking a look at the 22 & 6mm Beggs. there a bench restr round made by resizing 220 russian brass witha slightly differant shoulder an I beleave radious,s to e;leminate case stretch. the round has set records. it retains the same case taper. there is a 17 beggs an a 20 begggs also an likley a 6.5 beggs. case capacity is almost identical to he original brass. I have tried contacting Gene Beggs but so fat no luck, hes on bench rest central from time to time an it apppears he sells dies an the reamers are avaliabe from PTG in turn an no neck turn versions . he states he gets dies made for him by hornady that are a bushing die an that the same die is used for a both the 22 an 6mm version just changes the bushing an Im guseeeingthe expander. the beauty of the beegs round would be le

Its basicaly just a necked down 7.62x39. I donmt know what the neck dia would be on a necked down 7.62x39 case you might have to reatm or turn the neck to make it work on his reamer design. untill I get dies an try to rezise I will not know. I cant psot on bensch rest central for some damm reason been trying for a year or id ask if an y one has ever tried to use x39 brass for a beggs round.

220 russian has a small primer an flash hole. x39 is large primer except for the old remington brass.

I do al ot of work on the AK plat form an have built several sub 1/2" guns that i varmint hunt with . (26" barreld 223, 17-223 an working on a 6mm BR currently)

the AR feeds just fine if IF its got ammo designed for it. how ever the tapered cases make it impossable to use tapered rounds. there are special 7.62x39 mags an they work with varing sucess. there are a lot of 7.62x39 uppers out there. The AR is stuck with its short mag well other weapons like the AK are not. A ak can be have the magwell inlarged to hande rounds as long a 30-06 even . MY 223 varmint set up will run 90 grain high BC bullets loaded to proper length out of a modifed mag in SA you cant do thiat with a AR there hand feed only. The AK is not stuck with a weak bolt an can run bolt faces to over .500 with mods an the guns will handel more pressure than a AR an if you reall want to strp it up get a 308 Saiga bolt an trunion an run 65,000 PSI. There is not a lot of reason to stay with a AR length round if you not using a AR IMO.

MY 260 remington AK47 conversion loaded light will blow the doors off any Grendel its not stuck with the short mag well.

LINK TO 6MM BEGGS

http://bulletin.accurateshooter.com/...-texas-tunnel/
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Old September 2, 2012, 01:37 PM   #8
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doesnt it just make sense for all the x39 rifles on the market to use a necked down version of the 7.62x39 case with its original taper so it could easily and freely use all the magazines out there?...
You seem to see the curved magazine of the AK as a feature rather than as a bug......
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Old September 2, 2012, 03:43 PM   #9
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The curved mag an the tapered case is a bug for guns designed to shoot s sraight case. the cuved mag a tapered rounds are certainly a feature to a Semi Auto if you want it to shoot in adverse conditions an be able to chamber an extract in those conditions. In a AR it a issue because its not designed to shoot them. Its alos not as reliable as designed VS other battle rifles shooting simular length rounds.
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Old September 2, 2012, 04:12 PM   #10
jason41987
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the AK can use any shape magazines it wants for rounds tapered however it wants... the "bug" is that straight magwell in an AR15 that restricts it to rounds with little or no taper

all these new rounds coming out.. many of them decent, are designed to appease the AR15 crowd... however, those of us with essentially any other rifle, be it semi automatic, single shot, or bolt action, tapered cases tend to perform better in feeding and extraction and is a feature that wouldnt necessarily be ignored in favor of fitting in a confined magwell on one rifle in a world of dozens of designs that would be better with a more tapered cartridge

so does anyone out there have a wildcat that is simply a necked-down 7.62x39?
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Old September 2, 2012, 04:42 PM   #11
1BIGGUN
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Quote:
so does anyone out there have a wildcat that is simply a necked-down 7.62x39?
YES

As started in my previous thread the Beggs rounds are pretty close to what you talking about same case taper, same case capacity, same case, just a slight tweak to the neck. you could likey make it from 7.62x39 brass in single pass. you would never know it wasent a simple neck down if you were not told. the round is proven very accurate holds world records.

there are also guys who have done 6mmx39 with no changes but the neck but they get brass stretch an have to trimm a lot more when they reload. A

you can likley take redding S series busshing dies for a 7.62x39 an an use a .272 bushing an form a necked down 7.62x39 or better yet a necked up 220 russain with good brass. a reamer can be had for $140 from PTG done on you case. is not really that hard.

I was looking hard at the 6mm beggs on a target AK as well for use in a bench rest type bolt action. I decided a 6mm BR or dasher was closer to my needs at long range.
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Old September 2, 2012, 05:08 PM   #12
jason41987
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besides that link you gave me, not much to be found on 6mm beggs, even less on 6.5... hmm

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Old September 2, 2012, 05:27 PM   #13
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hmm.. so these redding dies have an adjustable bushing to fine-tune the shape of the case mouth.. which allows me to take an otherwise normal case and neck it down or up to whatever i need?

and should i find it necessary to create a different shoulder angle, the best way to do this is have the chamber made, load the brass with a fire-forming load and fire it in the rifle so that the brass will be forced to expand to the shape of the chamber, at which case im guessing you would anneal and reload as normal?
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Old September 2, 2012, 06:36 PM   #14
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go to benchrest central an do a search he is a meamber there.

here is a link to a thread I started on a differant site.

http://www.gunco.net/forums/f244/220...47-bolt-67626/

a bushing die can help you neck up an down. you may be able to go from .308 to 6mm in a standard die. guys neck down 7.62x39 to 6.5 mm an then blow it out with fore forming al the time.

nothing is super simple but yes its would be really easy to make a 6mm or 6.5mmx39 on russian brass. espeicaly ig you went up froma 220 russain then al you nned to do is expand the neck.

you can get a reamer an a die blank for under $100 at PTG to make your won dies.

redding bushing dies are not cheap. Hornady will not sell the beggs dies to the general public they need to go through gene beggs. I have his email an phone number some were. he never replied to my email an I never got him on the phone. but im sure the dies are avaliable. you can also just call Dave at PTG an have him sell you a finish reamer an likely a sizing reamer die then you will not need to buy any thing from Mr Beggs. Beggs from what I have read is a really well known bench rest shooter an has a indoor shoooting tunnel in Texas. Id simply contact him an ask for a set of dies an try to size down 7.62x39 brass with them see what you get for a neck OD and them order a reamer based on the round a bullet you want.

Id liket to get on bench reast central but event hough im registerd i cant seem to post or reply a damm thing an mu emials to there administrator go un answered.
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Old September 2, 2012, 06:38 PM   #15
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hmm.. so these redding dies have an adjustable bushing to fine-tune the shape of the case mouth.. which allows me to take an otherwise normal case and neck it down or up to whatever i need?
the bushing will adjust the neck OD only this is genraly used for adjusting tension on the bullet.

Gene beggs stated he uses the same die to make boththe 22 an 6mm round by changiung bushings.
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Old September 2, 2012, 06:48 PM   #16
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http://benchrest.com/showthread.php?...ight=6mm+beggs


contact info for MR Beggs.

I still cant post there myself?????????????????
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Old September 2, 2012, 07:04 PM   #17
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i could measure the thickness of my brass and determine the OD needed for the bullet size i wanted... curious though, would this shorten the neck, or would it change the angle of the shoulder to make it a 6.5 or 6.8?... i dont want to go too small in diameter because id like to be able to use it for hunting as well..

also, i was comparing 6mm, 6.5mm 6.8mm, and .308 caliber projectiles, comparing projectiles that had the same length to width ratio, so bullets of identical shape, but different sizes... found that they all had similar ballistic coefficiencies, but for some reason the 6.5mm bullets had a bit more... any reason why these seem to be ballistically better at similar profiles?
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Old September 4, 2012, 07:24 AM   #18
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Quote:
MY 260 remington AK47 conversion
Now that's interesting ...
Details in another thread, please?
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Old September 4, 2012, 10:16 AM   #19
jason41987
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.260 remington AK conversion probably isnt an AK... my guess is it started as a .308 saiga, and was converted with a barrel change.. its actually possible to convert a saiga to any of the many .308 based cartridges with just a barrel change
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Old September 4, 2012, 04:52 PM   #20
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Gotcha...
I've wondered about taking an M1A and re-barreling to 6.5...but wondered if the expense would really yield the accuracy I'd be looking for out of that platform...

Same concept as the Saiga, I guess...

Sorry bout the hijack, OP...but how does that .260 Saiga shoot?
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Old September 4, 2012, 06:06 PM   #21
jason41987
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id be interested to know as well... ive seen some saigas shoot close to 1MOA with a quality barrel.. and crappy barrels are reponsible for a lot of AK-related rifle inaccuracies
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Old September 7, 2012, 04:35 PM   #22
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I'll repeat a postulate I saw on another forum. The x39 cases and most/all other cartridge cases originally designed to be manufactured from steel are tapered to provide optimal feeding and extraction from the chambers of battle rifles. Using this design as is by simple neck reduction is counter productive from an accuracy and performance standpoint when using brass cases.
Chamber pressures can be higher with parallel case walls(brass cases) w/o excessive bolt thrust. Performance and accuracy are normally enhanced since there's less bullet to neck misalignment with less tapered sidewalls.
The less developed countries used what was available w/o much regard for what might have been improved as witnessed by the decades long use of the 7.62x54/ 7.62x39 when better, more powerfull, modern designs could be had. What was good enough in the 1890's or 1947, was/is still good enough.
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Old September 8, 2012, 08:29 PM   #23
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5.45

Not sure how this fits in..........but isn't the com bloc 5.45x399 the very thing that is being questioned......the 7.63x39 necked down??
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Old September 10, 2012, 06:53 AM   #24
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Sort of ish.
It puts a high SD smaller cal bullet in the AK platform. I have an AK74 and an AR 5.45 upper. Both are a little picky if you want decent accuracy. Only reason I have them is the ammo I bought supe cheap about 5-6 years ago and to offset the possibility of UN troops showing up with arms/ammo as different from what most Americans have as possible.
The only real good ammo I've shot is the RWS high dollar stuff and Hornady V-Max. On the plus side, if confronted by several aggressors, you can count on the so called hollow point European ammo to punch through 2 or 3 per round.
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