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View Full Version : 6.5mm grendel, or 6.8mm SPC for multiple rifles?


jason41987
August 25, 2012, 04:53 AM
hey everyone.. this isnt another 6.5mm grendel vs 6.8mm spc debate about what has better ballistics, what works better in AR15s.. because honestly it doesnt matter to me... so id like to avoid debates relating to the individual rounds

what this is about though.. is converting multiple lighter caliber military rifles to fire a single cartridge.. so that for the majority of my rifle shooting i wont need to supply more than one type of ammunition

rifles to be converted will include an AR15.. the easy one, but other rifles to be converted will require machining new barrels as well, and possibly work on bolt faces, if not new bolts entirely fabricated (something id like to avoid)

--- rifles

rifles include AR15, AKM, VZ-58, SKS, sig 551-A1 (or 556R) possibly add an HK93 to the collection at some point, id also like to get an AR-180 at some point as well... and when finally released to the civilian market, i really want one of those CZ-805 rifles....

so these are some examples of the semis.. but ill probably get a super short action bolt gun chambered in the same as well

--- reasons why i dont want 5.56mm

i feel we can do better in the same length action than 5.56, i would take it over 7.62x39 or 5.45x39 any day, but i dont believe its the best out there for general-purpose use.. also, hunting deer for now, and possibly elk in the future is highly likely, and 5.56mm/223 is simply illegal in a lot of areas, so id like to avoid it

--- some thoughts

6.5mm grendel requires no bolt machining on 7.62x39mm rifles, barrels in 6.5 are easier to find with a greater variety of groove patterns and twist rates, and bullets are more plentiful.. converting this would require no bolts to be made from scratch and only require 5.56mm bolts to be machined up... downside is no place ive been to carry 6.5mm grendel ammo, and because of alexander arms holding the rights to it all the way up until february of this year, its growth in the aftermarket community has been stunted, and few people carry chamber reamers for this cartridge

6.8mm SPC is more plentiful, better supported by the community.. downside is .270 caliber barrels are almost always geared towards .270 winchester rifles and theres not as many .270 bullet choices on the market, 5.56mm rifle bolt faces wouldnt need to be machined up by much, but 7.62mm rifles would require new bolts made entirely.

--- finale

so which of these two (and possibly similar-performing wildcats if they offer something these dont) do you believe would be the best cartridge for a multi-rifle conversion?... why do you think think one or the other would be easier to convert multiple rifles to.. and which one would be easiest to find (or make) ammunition for, including the possibility of re-shaping common pre-existing brass?

and again... ballistically i feel theyre too close to care either way so i dont want to get into a debate about excessively long ranges or "stopping power"

TimW77
August 25, 2012, 04:31 PM
I thought you were already the self-proclaimed expert on this subject!:rolleyes:


"6.5mm grendel requires no bolt machining on 7.62x39mm rifles, barrels in 6.5 are easier to find with a greater variety of groove patterns and twist rates, and bullets are more plentiful.. converting this would require no bolts to be made from scratch and only require 5.56mm bolts to be machined up..."

So NOW you are finding there was merit in others argument for the 6.5 Grendel during your rants against the Grendel!!!


"downside is no place ive been to carry 6.5mm grendel ammo..."

Never had a problem finding Grendel ammo.


"...and because of alexander arms holding the rights to it all the way up until february of this year..."

Duh, February of THIS year was SIX MONTHS AGO.


"...its growth in the aftermarket community has been stunted, and few people carry chamber reamers for this cartridge"

How many do you need? One?


"...downside is .270 caliber barrels are almost always geared towards .270 winchester rifles and theres not as many .270 bullet choices on the market..."

Another argument you ignored during you anti-Grendel rants.:D


"...easiest to find (or make) ammunition for, including the possibility of re-shaping common pre-existing brass?"

Grendel is easily made from 7.62X39mm of course.

T.

jason41987
August 25, 2012, 04:45 PM
can grendel actually be made from 7.62x39mm brass?.. its not a bit of a stretch going from that smaller diameter shoulder up to the nearly full diameter that the grendel shoulder is?...

also, i still like the 6.8mm cartridge more if i was chambering an AR15.. but i have to consider what it would take to convert multiple rifles.. and to convert a 7.62x39 rifle to 6.8 usually means having an entirely new bolt fabricated which would start racking up costs... i can get by in an AK without having to do that, but i dont think id be so lucky with a VZ58 or sks

ill admit though, in the last few weeks ive started to become pretty anti AR15 because the more i work with this rifle, the more glaring its flaws are to me.. although this is the easiest one to convert to a new cartridge, itll probably be the last one i end up converting because i just dont care enough about AR15s at this point

despite which cartridge i decide on the first one to be converted will be an AKM rifle... im going to build this from parts though since there are some changes ill be making to the parts selection vs a pre-made AK.. for example, using an ACE modular trunnion that rivets into the receiver and i can get a better end result just building this from parts.. however, i havent decided if i want to start with a polish or bulgarian kit.. with a bulgarian kit i would need to buy an extra front trunnion since the kits were originally made for milled rifles

second rifle... i really want one of those 551-A1/556R rifles... im really beginning to become a fan of the sig rifles that use the AK type magwell.. it allows magazines that are fully curved which does reduce magazine-related malfunctions, and i do like the "rock and lock" setup

someone told me 6.5mm could not use standard 6.5mm (.264") bullets because theyre designed for 6.5x55mm and similar power calibers... wasnt the idea of the shorter case body to allow a longer bullet so the grendel could use standard 6.5mm bullets? i thought that was the purpose.. i could be wrong though

but.. as states, i dont find too many barrel manufacturers that have the reamers for this cartridge, so even though i can find more twist rates and groove patterns, few people have the reamers... and ive also been keeping my eye open for .264LBC as well

on that note... with the standard 1:8 barrel, what are the better groove patterns to look for?

jason41987
August 25, 2012, 05:13 PM
when i do get around to converting an AR15... im probably going to modify the lower into something like an AR-47 lower so i can fix atleast one of the AR15s major flaws.. that straight magwell... would be better if they beveled the front of the magwell and used something more like an AUG or G36 magazine which is a straight in drop free style mag, but fully curved...

problem then becomes magazines... can a 5.56mm AK magazine be used?... well, can any 5.56mm magazine be used for the 6.5? and if so.. how many rounds would you lose out on in the capacity?.. actual AK-47 magazines are too curved for a relatively untapered cartridge and the COAL allowed is a bit shorter

... if i could have all of these rifles converted to use AK magazines.. perhaps a wildcat based on the 7.62x39mm cartridge by simply necking it down would be a better option since it would solve the magazine issue

bedlamite
August 26, 2012, 07:58 PM
Why don't you just get a FAL or M1A or whatever floats your boat in 308. There are obviously way too many shortcomings in both of the 6.x cartridges since they were designed to improve the performance on the gun you don't like anyway (http://thefiringline.com/forums/showthread.php?t=499372)

http://i328.photobucket.com/albums/l342/1k_wayne/junk/ugh.gif

jason41987
August 27, 2012, 10:34 AM
they were designed to improve performance on the 5.56mm, obviously the AR15 was the one they had in mind but its not the only 5.56mm platform out there that could benefit from an increase in performance.. i see no reason to restrict a good cartridge to a lesser platform just because its more common and easier to convert.. in fact, first rifle to get converted will most likely be an AK

tobnpr
August 27, 2012, 04:21 PM
someone told me 6.5mm could not use standard 6.5mm (.264") bullets because theyre designed for 6.5x55mm and similar power calibers... wasnt the idea of the shorter case body to allow a longer bullet so the grendel could use standard 6.5mm bullets? i thought that was the purpose.. i could be wrong though


Huh?
6.5 mm is 6.5 mm....

The Grendel most certainly uses 6.5 mm (.264 inch) bullets.

There is a wide weight range of 6.5 mm bullets- from 100 grains, to over 140 grains. The bullet selection depends on the amount of boiler room you've got behind the bullet.

140 grain bullets are fine outta the 6.5 Creedmore, it's got 53 grains/H20 capacity (or the .260 Remington, with a few grains more capacity).
A bit too heavy (though supposedly "doable") from the Grendel, with a case that only holds only 35 grains of H20...

No different than .30 cal bullets, for example.
I wouldn't shoot 240 grain bullets from my .308, but you sure can from a .30 magnum...

jason41987
August 27, 2012, 04:47 PM
this wasnt relating to bullet diameter but the ogive shape of the bullet.. which didnt make sense to me because i thought the purpose of the grendel was to use the longer 6.5mm bullets

jimbob86
August 27, 2012, 05:10 PM
I think you would be better served keeping the guns you have in the calibers they were built in. You want a 6.5 or a 6.8? Build one. Build one of both. Build more than one of both........ You just don't want to be the guy that converted his entire collection to a cartridge that the industry one day up and decides it does not want to support any more...... You really wanna put all your eggs in one experimental basket?



and theres not as many .270 bullet choices on the market,

Around here, there are more .277 component bullet choices on the shelves than there are .264 component bullet choices. YMMV.