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Author Topic: Thinking out loud  (Read 2467 times)
SHORT-N-SASSY
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« on: March 16, 2018, 06:58:15 AM »

Why I probably won't do the AR-10 short-action magnum trip, this time around.

It's spring, 2001. I'm working on completing my AR-10'er Collector's Edition 2001, and have an American Spirit Arms side-charging .308 16"-barreled Carbine on hand for evaluation. Winchester just announced their .300 Winchester Short Magnum (WSM) cartridge. I'm impressed with the cartridge's performance, from a short-action rifle platform. I decide to purchase the .308 carbine from American Spirit Arms, sans the barrel. I complete the Collector's Edition, and begin work on the project with Carl Emmite, Accuracy Systems, Inc. (http://65grendel.com/forum/showthread.php?7360-6-5-gap-rsaum&p=107676&viewfull=1#post107676). Carl and I are really excited, as we're among the first to build an auto-loading .300 WSM, at the time:

The "fat lady" executing a graceful exit through the slightly-widened ASA .308 ejection port.

Back to the future: Today, Accuracy Systems, Inc. offers a wide selection of magnum chamberings for the short-action AR-10:

(http://www.ar-10-rifles.com/index.php)

Now, I've long since sold to a guy the 24-inch .300 WSM Barrel and modified AR-10 Bolt used in the 2001 .308 ASA Match Rifle .300 WSM Conversion Small Arms Review article. But, I still have the American Spirit Arms rifle, now equipped with an 18" .308 Winchester barrel:


30" "Sidewinder" gas tube:


And, an AR-10 magazine, with the front cut-out to accept a cartridge overall length of 2.950":


Bottom Line: All I would need to complete a Hornady 6.5 PRC - AR-10 conversion would be a Barrel and Bolt:


But, this is 2018. The Eugene Stoner-designed AR-10 --- a good design, overall --- has been around for 62 years. We're, now, well into the future. It's time for a change --- and, Bullpups are hot!


« Last Edit: March 17, 2018, 04:06:40 AM by SHORT-N-SASSY » Logged
SHORT-N-SASSY
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« Reply #1 on: March 18, 2018, 03:58:55 AM »

The challenges and rewards of trespassing beyond the safety of the well-worn trail in today's shooting world.

I'm delighted with the recent introduction of the IWI Tavor 7 .308/7.62x51mm NAT0 Bullpup --- incorporating a short procedure for changing ejection side, from right to left. That speaks reams about the industry listening to shooters' complaints. Along with the Kel-Tec RFB .308, the K&M Arms M17S 7.62/.308 Winchester and the Desert Tech MDR .308, that brings to four, the number of Bullpup rifle designs today's experimenter can consider as a basis for an experimental short-action magnum Bullpup. And, the person attempting to modify a firearm design should respect the manufacturers' disclaimer on same, "Altering or modifying parts is dangerous and will void the warranty."

Whereas, the IWI Tavor 7 .308, K&M Arms M17S .308 and Desert Tech MDR .308 have front-locking breech designs, the Kel-Tec RFB .308 incorporates a rear-locking breech design. From this experimenter's perspective, I'll pass on the Kel-Tec .308 RFB ---

(https://www.ingunowners.com/forums/gunsmithing/328413-rear-locking-lugs-vs-front-locking-lugs.html#post4711430)

Which leaves the Tavor 7 .308 front-locking design ---


The Desert Tech MDR .308 front-locking design ---


And, last, but not least, the K&M Arms M17S .308 "No-more-Mr.-Nice-Guy-3-lug-triangular-Bolt" front-locking design ---

(http://bullpupforum.com/index.php?topic=6302.msg74412#msg74412)

To clarify: The Bolt face diameter of the short-action magnum Bullpup candidate has to be opened-up from 0.473" to 0.532": a difference of 0.059". Simply put: The gunsmith has to remove 0.0295" (The diameter of a guitar D string is 0.0260"), all around, from the inner circular surface of the Bolt face. And, it has been my experience that some modification to the extractor and ejector(s) is also required. An adjustment to the Barrel diameter/contour, immediately forward of the Barrel Extension, may be required as well.

Such is the price for standing-up to the painfully-slow evolution of American sporting arms and ammunition:
(https://www.americanrifleman.org/articles/2009/10/15/innovation-in-the-american-firearms-industry/);

(http://innovationtrail.org/post/innovation-gun-industry).

It's been my experience that the rewards for a successful challenge far outweigh the effort and costs involved.

Give this right-handed, left-eye dominant Bullpup'er (who shoots a rifle from the left shoulder) an ambidextrous .308 Bullpup, with a beefy 3-lug Bolt and free-floating Barrel --- and let him do his thing.




« Last Edit: March 19, 2018, 01:21:13 AM by SHORT-N-SASSY » Logged
SHORT-N-SASSY
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« Reply #2 on: March 20, 2018, 09:15:24 PM »

Under the heading, Is there a CMMG MK3 CBR 6.5 PRC in the offing?, I today sent the following e-mail to CMMG, Inc. President & C.E.O., Jeff Overstreet:




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SHORT-N-SASSY
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« Reply #3 on: March 22, 2018, 05:18:45 AM »

If only . . .

Back on February 15, 2015, I sent an e-mail-request to Jason Hornady:


The following day, Mr. Hornady replied, "Thank you for the email . . . . We have discussed something similar, no promises."

Now, Hornady has been shipping 6.5 GAP 4S SAUM brass, with the Hornady headstamp, to G.A. Precision, for some time ---


And, Copper Creek Ammo has been using that Hornady brass in their 6.5mm RSAUM loaded ammunition, which has a cartridge overall length (C.O.L.) of 2.850" ---

(http://coppercreekammo.com/product/65saum-143eldx/)

Now, consider the AR-10 magazine inside length, and with the front cut-out: Factory-loaded 6.5mm SAUM ammunition would fit in the AR-10 magazine, without any problem ---


I received a reply from CMMG, yesterday:


The good news: CMMG engineers expressed no qualms with the AR-10 breech design. However, they took issue with Hornady's maximum C.O.L. for the new 6.5 PRC cartridge. A reliable source has stated that, "Hornady factory ammo is measuring 2.945" for both the 143 gr ELD-X and 147 gr ELD Match."

If only . . .
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racky
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« Reply #4 on: March 23, 2018, 12:42:44 AM »

S-N-S, so are you saying that these new cartridges could fit in a Tavor 7 with a new barrel & bolt?Huh?, or their strictly for bolt guns, or exotic super custom AR 10"s,???
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SHORT-N-SASSY
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« Reply #5 on: March 23, 2018, 03:49:20 AM »

S-N-S, so are you saying that these new cartridges could fit in a Tavor 7 with a new barrel & bolt?Huh?, or their strictly for bolt guns, or exotic super custom AR 10"s,???

racky,

Thanks for stopping-in. First, a word about "Thinking out loud":


Putting it mildly, Hornady threw short-action auto-loading rifle shooters a curve ball: Instead of offering us factory-loaded 6.5 GAP 4S SAUM ammunition, which is typically loaded to a cartridge overall length (C.O.L.) of about 2.850", their Hornady 6.5 PRC cartridge is typically loaded to a C.O.L. of 2.945". That 0.095" increase in C.O.L. effectively closes the door to short-action auto-loading rifles, which use detachable magazines with an inside length of approx. 2.865".

Now, Copper Creek Cartridge, Co. offers factory-loaded 6.5 GAP 4S SAUM ammunition. And, their 143-grain Hornady ELD-X loading is 2.850". So, at the present time, short-action auto-loading rifle shooters who wish to venture beyond the 6.5mm Creedmoor, have an option.

And, re your question about the IWI Tavor 7 .308 suitability as the basis for a 6.5 GAP 4S SAUM or Hornady 6.5 PRC conversion, only the 6.5 GAP 4S SAUM can be considered. However, one would have to consult with a competent gunsmith to determine whether, or not the breech design merits the upgrade. If so, then the challenge of adjusting the present gas system/designing a new gas system would be in order.

Personally, I'm back to square one: I still have the American Spirit Arms .308 AR-10 that I used for the 2001 .300 Winchester Short Magnum conversion. And, as noted above, I've since sold the .300 WSM Barrel and modified Bolt, but still have the "Sidewinder" gas tube and cut-out magazine. But, I'm a Bullpup'er. If a major ammunition manufacturer gave us a factory-loaded 6.5 GAP 4S SAUM or 6.5 PRC cartridge, that was loaded to a C.O.L. shorter than the inside length of an auto-loading short-action rifle magazine, I'd be considering converting one of the auto-loading Bullpup carbines on today's market.

Stay tuned.


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SHORT-N-SASSY
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« Reply #6 on: March 23, 2018, 01:14:18 PM »

Update: A 6.5 GAP 4S SAUM/Hornady 6.5 PRC-AR-10 conversion is doable.


(https://imgur.com/gallery/9FUnp)





(http://forum.snipershide.com/threads/new-gap-extreme-hunter-in-6-5-saum.169451/page-36#post-3318334)

I today called Copper Creek Cartridge, Co. They offer precision hand-loaded 6.5 GAP 4S SAUM  and  Hornady 6.5 PRC ammunition. The good news: Both offerings have cartridge overall lengths  shorter  than the inside length of AR-10 magazines (using the 2.865" inside length of my American Spirit Arms .308 magazines, as a guide). I asked if their customers used these offerings in AR-10's. The answer was in the affirmative!
_ _ _ _ _ _ _ _ _ _ _ _

ETA:
KAC and Larue LR/SR25 mags allow 2.871"
(http://forum.snipershide.com/threads/ar-308-magazine-maximum-coal.6544417/#post-6544611)
« Last Edit: March 23, 2018, 03:08:46 PM by SHORT-N-SASSY » Logged
SHORT-N-SASSY
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« Reply #7 on: March 25, 2018, 12:09:49 AM »

Concerned about the long C.O.L. of factory-loaded 6.5 PRC cartridges, and its effect on short-action auto-loading shooters, I today e-mailed Jason Hornady expressing my concerns: (http://www.65grendel.com/forum/showthread.php?7360-6-5-gap-rsaum&p=188393&viewfull=1#post188393).
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SHORT-N-SASSY
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« Reply #8 on: April 03, 2018, 01:57:13 AM »

". . . I could build a custom AR that is reliable, accurate, and perfect ergonomics for me . . . The only trade off is that it isn't a bullpup." (http://bullpupforum.com/index.php?topic=12968.msg138712#msg138712).


(http://bullpupforum.com/index.php?topic=7246.msg71466#msg71466)

(https://www.ar15.com/forums/precision-rifles/-/4-7781/?)

I hear ya, whiskey91lima.
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SHORT-N-SASSY
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« Reply #9 on: April 15, 2018, 03:32:59 AM »

If only . . .

Back on February 15, 2015, I sent an e-mail-request to Jason Hornady:


The following day, Mr. Hornady replied, "Thank you for the email . . . . We have discussed something similar, no promises."

Now, Hornady has been shipping 6.5 GAP 4S SAUM brass, with the Hornady headstamp, to G.A. Precision, for some time ---


And, Copper Creek Ammo has been using that Hornady brass in their 6.5mm RSAUM loaded ammunition, which has a cartridge overall length (C.O.L.) of 2.850" ---

(http://coppercreekammo.com/product/65saum-143eldx/)

Now, consider the AR-10 magazine inside length, and with the front cut-out: Factory-loaded 6.5mm SAUM ammunition would fit in the AR-10 magazine, without any problem ---


I received a reply from CMMG, yesterday:


The good news: CMMG engineers expressed no qualms with the AR-10 breech design. However, they took issue with Hornady's maximum C.O.L. for the new 6.5 PRC cartridge. A reliable source has stated that, "Hornady factory ammo is measuring 2.945" for both the 143 gr ELD-X and 147 gr ELD Match."

If only . . .


Remington Arms Company LLC to the rescue, please ---

(https://www.ar15.com/forums/Precision-Rifles/AR-10-ers-bummed-by-Hornady-s-6-5-PRC-2-955-Max-C-O-L-Not-to-worry-The-6-5-GAP-4S-SAUM-option-/4-7781/#i105217)

« Last Edit: April 15, 2018, 03:42:05 AM by SHORT-N-SASSY » Logged
SHORT-N-SASSY
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« Reply #10 on: April 21, 2018, 04:25:07 AM »

Escape from the 20th Century

waveslayer,

Re: (http://www.ar15.com/forums/Precision-Rifles/AR-10-ers-bummed-by-Hornady-s-6-5-PRC-2-955-Max-C-O-L-Not-to-worry-The-6-5-GAP-4S-SAUM-option-/4-7781/#i105587)

My ultimate goal is a state-of-the-art (read: miles ahead of today's "battle rifle" thinking) short-action auto-loading Bullpup rifle chambered for the 6.5mm SAUM cartridge --- hopefully, with a Remington headstamp.


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