65 Receiver Set with Polymer mags from PF (HOPEFULLY)

[cory]

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The whole idea here is pushing the performance of the Grendel case with a new receiver set that can take polymer mags, but why then limit ourselves to a Grendel case if we're building a new receiver set and magazine.

One answer to that could be that the AR15 magazine size is one of the most efficient ways of carrying a lot of ammunition in a small space on the soldier's load, which is a military application only problem and solution. We then have to ask where the optimum magazine size/capacity/cartridge performance/weight data points are.

If 5.56 NATO STANAG mag size/capacity/performance/weight is considered the minimum, and 7.62 NATO SR25 is considered the maximum, where do you want to cover down?

The harder we push for performance, the closer we get to the penalties of 7.62 NATO.
The tighter we restrict to 5.56 NATO dimensions, the more the existing 6.5 Grendel advocates for itself.

If we want to push the pressures, we definitely need a whole new upper receiver, barrel extension, and barrel tenon diameter. There are a bunch of guys learning the hard way right now about this with .473" diameter head cases stuffed into the AR15, pushing the pressures from 55-60ksi with only .136" wall thickness.

Are you not the one who advocates for the Grendel to be used as a LMG and DMR/Light Sniper Rifle? The latter would never happen with the current magazine options. And no reliability is not the problem. It's that annoying rattle when you load the magazines near max. It's rather hard to conceal your position when every time you move, it sounds like a monkey playing in the junkyard.

The fact is the Grendel in the AR15 does leave performance on the table, even if we want to keep the 55ksi max. This is especially true with solids. It would be nice if we could make use of the Barnes 127gr LRX. To bad we don't have a magazine that would allow us to load it long enough to get useable velocity.

You may think that the performance increase is negligible and I do tend to side with you. However, the market has shown that it'll pay premiums for marginal improvements (weight reduction, .....). The 6.8 has taken a huge share of the marketplace because of nothing other than dedicated marketing. We need to do something to take back that market share. Only then will we get more Grendel dedicated products brought to the market. I want more affordable bullet options! haha

Nobody, who has ever did a magazine change under pressure, will tell you that .308 mags are the answer (except some NFL lineman). Forget about magazine retention. They're just to big.

We need 25-30 magazines that work reliably and don't rattle. Narrowing the ID of the magazine maybe a solution for getting a polymer magazine that doesn't rattle. However, I suspect that this magazine in a 25-30 variant would be so long that firing from the prone would not be feasible.

Of course the smallest package that meets requirements is always the best answer on the battlefield. The 5.56 does a great job with this. However, that package seems it's just to small to meet requirements. We may need to look at going the width of the AR10 magwell, with the length + 0.100" of the AR15 magwell. We can still keep weight and size down by keeping AR15 BCG and extension.