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Possible spin off from the 7.62x39, Grendel 6.5

12127 Views 36 Replies 13 Participants Last post by  tinman
One of the primary issues with the 7.62x39 has been getting the magazines right it seems, the bolt and barrel side seems OK.

In that case I would like to see the 6.5 Grendel as an option.


Magazines are already out and operational an fit a standard XCR 5.56 lower
Conversion is relatively simple for the 7.62x39 bolt face
6.5 gives almost identical performance and better range than the 7.62 NATO
6.5 unlike the 6.8SPC can come in a wider range of grain weight allowing tweaking the capability


Limited but increasing numbers of makers of this calibre
Proprietry round owned by Alexander Arms, means licencing
Means I would only need 1 XCR for 7.62 NATO performance, would have to justify buying another......

Still want it ....... ;D
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i also would like a conversion kit in 6.5 grendel. i currently have an encore chambered in this great little cartridge. pure fun to hunt wild pigs with. ;D
I think the biggest plus for 7.62x39 to me is the relative low cost of the ammo. I to would like to see the 6.5 available. The more the merrier I say. But ammo seems even less available and more costly than 6.8. That may be a cold start for the 6.5.

I for one am really looking forward to the 7.62x39 conversion kit. I am not looking forward to having to buy all the magazines I will no doubt purchase with the kit but it is what it is. For the record I am a magazine whore!
Early next week we are making a short run of 6.5x39mm barrels (We cannot call it what you call it) for testing and evaluation. If all goes well, we will put them into production.

We are also making a .300 Whisper for a customer.
Gotta love those lawyers. Shakespeare had it right.
Oh, hell yeah. 6.5mm Whosit. I'm all for that.

To my mind, the 6.5 Grendel (or whatever) is a better round than the 6.8SPC. I regard the 6.8 as a 5.56 replacement or upgrade. The 6.5 really treads on the .308s toes ballistically. Which is good. Good enough that I'd reconsider an XCR-H if the Grendel (or whatever) is available.

Of course, this begs the question of ammo costs. Costs are so high (and availability so low) nowadays handloading is pretty much a must. 5.56mm is still champ in cheapness for reloading (even if it isn't nearly as low cost as it used to be). 7.62x39, though, is probably cheapest over the counter. Still, ballistics mean more to me than cost per pop. Handloading keeps all of them under control--relatively.
I'm really excited about the 6.5. I hope it works well. It should. We finished turning the initial 6.8s and we hope to turn some 6.5's this week. We must also call the .300 the .300-221. We cannot use the other name for that cartridge either.

The 6.5 has trouble exiting the AR15 receivers. This is why the ejection port must be increased. Because our ejection is more positive, we shouldn't have to increase the ejection port size.

I'm pretty jazzed about doing the 6.5. It will be my hunting rifle.


Alex J. Robinson

I'm going to have to start saving for a decent long range optics package now as well as a "6.5x39" conversion kit....... ;D

Oh and start reloading as well if I'm to start to wring the performance out of the XCR and calibre and keep my costs livable.


I know this is very preliminary stages but is there any info on optimum barrel length and twist, I wouldn't like to go over 18" but 16", 19.5" and 24" seem to be the released AR platform lengths.

Mutter, mutter, must try and hide expenditure from "she who must be obeyed"..... ;D
I know this is very preliminary stages but is there any info on optimum barrel length and twist, I wouldn't like to go over 18" but 16", 19.5" and 24" seem to be the released AR platform lengths.
This page may be of interest to you:

From that page:

twist rate = (150 * bullet diameter squared) / bullet length
bullet length = (150 * bullet diameter squared) / twist rate

twist rate = (180 * bullet diameter squared) / bullet length
bullet length = (180 * bullet diameter squared) / twist rate
for ar15's, the longer barrel's give higher muzzle velocities resulting in better range. bullet weights for the grendel seem to have a sweet spot bwtn 108 and 123 gr, but lighter and heavier weights are used with some success. i'm hoping for something bwtn 18 and 22 inches for the XCR, but i will take whatever i can get. ;D
Whatever barrel length is enough to keep a 120gr Nosler BT supersonic at 1000yds. I'm getting ambitious here.

I want this thing as a .308 replacement. For anything below 300yds, the .223 and 6.8 would be fine.
I'm interested in this caliber (6.5x39) as well. I'm planning on buying it when it's available.
Really excited to hear that a 6.5 x 39 or Grendel like barrel is being done. I have two Grendel's, a 16 inch and and 24 inch. First the ejection port does not really need to be enlarged, standard AR size works fine. Alot of info can be found at the Grendel site www.65grendel.com. Forming brass from the 7.62 x 39 is really easy or for top performance you need to get the AA or Lapua brass, if the chamber specs will be close enough to the 6.5 Grendel to allow firing of Grendel brass and fire forming it to the 6.5 x 39 chamber. A mid-weight 20 inch barrel would be a great all round length. It will provide enough velocity for long range use and still be short enough to be handy to carry. The website has tons of info on reloading and ballistic testing. If for some reason, you will not be able to use the AA or Lapua brass then the performance will suffer. The Wolf Grendel brass or fire formed 7.62 x 39 brass has been fine for milder loads but it is not the quality that you need the brass to be for getting the max load performance. The strength of the XCR platform may allow using a bit hotter loads that what the AR platform allows. AR bolts will break if pushed over max recommended loads for the Grendel. Check out the website for the most Grendel info. I will have to call next week to see how this is working out. Take care, Bruce
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I currently own a 6.5x55 Swed, and a 6.5x284 Norma. I LOVE the way 6.5 bullets perform. Have shot numerous deer and hog with both. The 6.5x284 is my "beanfield rifle." And although I have my order in for a 6.8 SPC barrel, I would definetly buy a 6.5x39. I use the Sportsmans Guide wooden bullet 7.62x39 Lapua now for cooking up softpoint handloads in the 7.62x39. You don't have to worry about looking for your expended brass (cases are excellent quality berdan primed, and throwaway). It wouldn't take much work to resize the Lapua cases to 6.5! Let me know when I can put my order in Alex! Gunner69
Sorry it took so long to post. We've been busy.

We built three rifles as follows: one with a 16" barrel with 1/8 twist; one with a 16" barrel with 1/9 twist; and one with an 18.6 barrel with 1/9 twist. We shot all three back to back with Wolf, AA Ammo, and some handloads.

The Wolf was interesting ammo, it has a very large lead tip which was easily damaged during loading. I.e., when I removed a loaded round from the chamber, I could see the tip was damaged. Nevertheless, we shot 5 shot groups with 4 shots under 1" and then one flyer. The AA and handloads were more consistent (no flyers). My friend who has two AA rifles in 6.5 and who shot we me said that the XCR shot as well as the AA rifles but had lighter recoil.

So, there you have it. We need input on what barrel lengths you guys want. We're ready to go into production. We're going to make 7.62x39mm bolts for these rifles this month. We'll make additional 7.62x39mm bolts for the 7.62x39mm rifles which will be available in December.


Alex J. Robinson
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Shooting these rifles back to back with the 3 twist rates, which one faired the best?
I tested only the 16" barrels with 1/8 against 1/9. My only 18.6" barrel was 1/9. I couldn't tell the difference between 1/8 and 1/9. The 1/9 18.6" barrel shot the best of all. But all were close.

I hope this helps.


Alex J. Robinson
Robinson Armament Co.

Thanks for the information. I have a tendancy to purchase a 16" barrel for my XCR in this caliber.

If you like, I will set up a poll and ask our members what barrel lengths they would like to see.
i'll take the 18.6 inch barrel. the two twist rates may be so close as to be a non-issue. great to get such good info straight from the man himself.
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