COAL and "Free" Velocity Gains

[din]

I don't know---- Then you'd have folks complaining about the massive jump to lands that factory Grendel fodder would have to make....

They're going to complain about something anyway, might as well make it something interesting.

[KentuckyBuddha]

No reason to complain! You just have an/some barrel(s) or barreled action(s) in SAAMI spec if you want to use factory ammo and you load your own for something like that.

[cory]

I don't know---- Then you'd have folks complaining about the massive jump to lands that factory Grendel fodder would have to make....

Just because the magazine allows for a COL of 2.405" that doesn't mean the barrel has to be chambered to allow ammunition to be loaded out that long.

[JASmith]

there are some long-nosed bullets that need to be seated a bit lomger than SAAMI length to minimize jump for best accuracy.


THE 2.405" magazine length would add the flexibility needed regardless of the velocity gain.

[Variable]

If I were rich (Bill Gate's son kind of rich), then just for orneryness I'd do the following:


1.) Neck the Czech 7.62x45 case down to 6.5mm.
2.) Have a new Lancer magazine made for it.
3.) Have a new larger bolt and barrel extension made for the new round.
4.) Have a new upper and lower made to accomodate the slightly larger mag and bolt.
5.) Give the new 6.5x45mm cartridge and rifle some incredibly spiffy names
6.) Hire some slick marketers to advertise my incredible new achievement in all the gun rags.
7.) Give them away to anyone that would write about them or had influence in the gun world.
8.) Make major campaign contributions to grease the skids and push for adoption. (J/K!!!! I have a soul....)

It'd be an AR12, and would split the difference between the AR15 pattern and the AR10/GII types.

ETA:

[sneaky one]

Von Gruff, I have a Cav Arms plastic AR lower that can be tweaked to run ammo at almost 2.390.- 2.400. I may make a Grrr AR max yet.

My AA (compound chamber) with 900-1000 rounds thru it has it's throat lengthened by .010 over the years. The original Gmx pills made contact at 2.3751-- with a 40 k jump.- I loaded them at 2.315. Are you using the AK brass, or Grendel brass to make your rounds?

I- we may be onto a something here that was previously missed. Hmmmm....

[sneaky one]

Variable, wouldn't it be so nice to be so rich as to have others post for us, while we reside in the pool area?

[JASmith]

If we're bumping the base diameter up to .473", then the 6.5 BR starts looking attractive: http://ammoguide.com/?catid=183

Case Capacity = 39.9 gr H2O.

[sneaky one]

Joe, I have looked at the BR also. Almost ordered a Carnivore - back in the day...

My Grendel ideas keep me rooted here. I like less powder burning . Less wear and tear on all items. Who knows?

If we can get the same performance from an 18" tube, using a mono pill,, as guys using std. pills in a 24" tube- all while using less powder- what's not to love? CFe rocks, so does a few other faster powders. Yahooo!

[Variable]

If we're bumping the base diameter up to .473", then the 6.5 BR starts looking attractive: http://ammoguide.com/?catid=183

Case Capacity = 39.9 gr H2O.

7.62x45 has roughly the same base diameter as Grendel (.445" vs. .440"), and holds 43.1grs. of H2O per Wiki.

https://en.m.wikipedia.org/wiki/7.62x45mm_vz._52 (Sorry for the cold link-- every time I hit the link button Safari crashes... I think it's my old ipad getting ready to die.LOL)

I don't know how many grains of capacity you'd have to play with after you necked it to 6.5mm though.

Since the 45mm case length equals 5.56, and the diameter roughly equals the Grendel, Stan might feel better about how it'd feed through links for beltfed ops.

[Von Gruff]

Von Gruff, I have a Cav Arms plastic AR lower that can be tweaked to run ammo at almost 2.390.- 2.400. I may make a Grrr AR max yet.

My AA (compound chamber) with 900-1000 rounds thru it has it's throat lengthened by .010 over the years. The original Gmx pills made contact at 2.3751-- with a 40 k jump.- I loaded them at 2.315. Are you using the AK brass, or Grendel brass to make your rounds?

I- we may be onto a something here that was previously missed. Hmmmm....

I bought a couple of boxes of Hornady Grendel ammo and used the brass from that for my hunting loads and to start the project but all my other brass is Lapua 7.62x39 brass.

As for the comment that it would be a problem putting store bought ammo in a chamber with 2.405 COAL then that can not happen as my chamber has the shoulder lengthened so there is no storebought ammo for it anyway.
My aim had been to maximise as much as was possible the case and magazine for my micro bolt action and has no relevance to any of the AR platform rifles at all because of their magazine restrictions.
A bolt rifle user who is a handloader exclusively can gain a lot from this but unless it is done as a whole concept there is no advantage to just doing part of it by loading long as the case capacity gain is marginal over what the lengthened case can offer along with the longer COAL.
Sneaky's loading to his potential for the 2.390 will still make the rifle a dual use of handload or storebought but can not ever match what I have without the case lengthening as well.

[JASmith]

7.62x45 has roughly the same base diameter as Grendel (.445" vs. .440"), and holds 43.1grs. of H2O per Wiki.

https://en.m.wikipedia.org/wiki/7.62x45mm_vz._52 (Sorry for the cold link-- every time I hit the link button Safari crashes... I think it's my old ipad getting ready to die.LOL)

I don't know how many grains of capacity you'd have to play with after you necked it to 6.5mm though.

Since the 45mm case length equals 5.56, and the diameter roughly equals the Grendel, Stan might feel better about how it'd feed through links for beltfed ops.

The fly on the ointment is the short noses needed to work within 2.60 OAL.

Now, if the action and magazine tolerates a longer OAL, then the story changes. For example, the BR max OAL IS 2.44" .

We might want to ask teh question: What actions allow intermediate cartridge lengths between 2.26 - 2.30 used by some in the Grendel and the 2.80" of the .308?