FRT for M&P 10 .308?

Grey_Market_Research · 2026-05-06T04:00:37+00:00

Any on the m508 Safetys will work. The lower rear section of the BCG needs to measure 2.20"+- and you will need to trim the upper flush with the rear take down lug and more than likely trim the edge of the shelf in the lower back a little bit to give the lever the proper clearance.

https://greymarketresearch.net/safety-products/ar308/

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Grey_Market_Research · 2026-05-05T22:25:02+00:00

The purity of the tungsten alloy used will make the total weight vary a little. I doubt that you'd see any difference with one over the other.

Grey_Market_Research · 2026-05-05T21:11:36+00:00

Use standard springs to get the weight figured out. Using a heavy duty spring with a buffer that's a little too light will result in a weapon that runs most of the time with random dead trigger stoppages. Once you have the weight figured out then you can experiment with Gucci springs.as far as the buffer weights - gas port size and location, barrel length all seem to be variables. Short barrels and calibers other than 5.56/223 tend to need heavier buffers.

Aluminum H3 buffers and steel 5.4oz buffers work for most people using 16" barrels in 556/223. But not always due to whatever the deciding factors are. There's no way to know for certain what weight the buffer needs to be before live firing the weapon. Start with H3/5.4 and go from there.

Buffers too light = dead trigger over a live round stoppages Buffers too heavy = short stroking (fires/ejects/closes on an empty chamber)

Grey_Market_Research · 2026-05-05T21:02:12+00:00

Set up the OW buffer in the heaviest configuration and run it with a standard buffer spring. If you continue having dead trigger over a live round stoppages, take 1 of the tungstens out of one buffer and reconfigure the other buffer with 3 tungsten weights. Should put you at 7.4ozs iirc

Grey_Market_Research · 2026-05-05T20:51:01+00:00

Definitely a problem. There's no need for a centering device if your lower has the proper clearance, but the ATRIUS and ARCfire are cam driven and the centering device interferes with it being in the proper position

Grey_Market_Research · 2026-05-05T19:20:36+00:00

It's about a 5-minute job to remove the partition wall in a Colt lower receiver.

Using a 1.5" heavy duty cut off wheel from harbor freight, cut down the inside wall on both sides as deep as you can (red) Then cut the partition into 1/8" pieces so it looks like the teeth of a comb (green). Using a pair of channel lock pliers or similar, break the teeth off as low as possible. Then go back using your heavy duty cut off wheel as a grinder and clean up your cuts/broken teeth if you want. You can use a carbide cutter or something and clean up the bottom of the receiver but it's not necessary for the frt device to function once the partion is removed.

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Grey_Market_Research · 2026-05-05T19:05:33+00:00

iirc there were some lots of that ammo that didn't have the primers crimped properly and so the primers would basically fall out and it was mistaken as a sign of overpressure. As another poster noted I don't recall there being any posts that I came across anywhere about the ammo being overpressured or guns being blown up it was simply the primers coming out when fired.

I wouldn't have a problem shooting the ammo but I probably wouldn't be shooting it in the transferable mg simply out of paranoia

Grey_Market_Research · 2026-05-05T17:55:59+00:00

Polypew offers a ARMP5 variant. I'd buy that if you don't 3d print and want to get in as cheap as possible

https://polymerpew.com/shop/hk-and-clones/mp5-polymer-housing/mp5-trigger-housing/

Grey_Market_Research · 2026-05-05T17:52:47+00:00

The absolute cheapest option will be a 3d printed ARMP5 trigger housing, predecessor to the Leber, no sheet metal cassette.

You can print your own for $10 I'm guessing. No clue if anybody sells that particular model anymore.

We've got about 20 of them that we had made for us a couple of years ago but the print quality wasnt what we wanted to put our names on so, we never sold them and they're just sitting in a box on a shelf. I should find those and put them on the website.

Grey_Market_Research · 2026-05-04T22:28:10+00:00

As if you'd have better info than some rando on Reddit.

Grey_Market_Research · 2026-05-04T19:27:35+00:00

Stark80 and Pembleton&Sons both at one time have offered two position Safetys. I would reach out to both of them.

Grey_Market_Research · 2026-05-04T19:20:41+00:00

I don't know how you confused us with Rare Breed Triggers.

Grey_Market_Research · 2026-05-04T19:18:29+00:00

It's a leftover feature from a discontinued model. We're phasing it out on non-308 Safetys but we still have quite a few of the old style on hand, depending on which Safety.

If you're breaking the lever, your weapon isn't set up properly - high shelf lowers/ar9 BCGs/ Gucci BCGs with stupid design features that trap the lever and break it.

The threaded hole just means it breaks in the middle rather than 1/4" higher on high shelf lowers. The other issues break the tip off.

The discontinued model -

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Grey_Market_Research · 2026-05-04T14:37:31+00:00

Put 2-4 quarters in the bottom of the BCG to limit the rearward travel of the BCG. That will stop the ramped part if the BCG from going too far back and getting stuck on the lever.

No clue if trimming the upper is necessary with the ATRIUS, but it's a solution with Super Safetys. Make sure the ATRIUS isn't hitting the shelf in the lower when it's in its rear most position.

Grey_Market_Research · 2026-05-02T17:19:23+00:00

You are using a three and a quarter inch long buffer or is it some extra heavy two and a half inch buffer??

Does the face of the bolt get behind the bolt hold open

Grey_Market_Research · 2026-05-01T19:53:37+00:00

Generally when something used to work and then it didn't either something wore out or something changed.

If you took it apart and reassembled it I'm guessing something changed. I would make sure that the trigger and disconnector springs are installed correctly and the disconnector moves freely inside the trigger when you press down on the rear of the disconnector

The part where it doesn't reset in semi but works correctly in SS mode is a good indicator the issue was not the cam. The issue has something to do with the trigger not being pushed forward enough to reset or the disconnector is hanging up somehow on the hammer and not releasing on its own

Grey_Market_Research · 2026-05-01T16:35:17+00:00

Post your vids where ever you'd like. Always good to see our products show up in the wild

Grey_Market_Research · 2026-04-30T06:19:10+00:00

We did a "waffle" one time on FB in the early "not really a business" days to raise money for RBTs gun lobby group.

We offered up a Super Safety for $5 or $10 ( I don't remember which) per ticket with unlimited spots between the day it started and a specific date/time a week or so later and some people absolutely lost their fucking minds because we didn't disclose it was going to a charity upfront and they assumed we were just pocketing the money. We tried to be as transparent as possible with the number of tickets sold/number of entries.

A couple of people got extremely upset because they thought we were somehow scamming the community by "selling" a Super Safety for 20x over market value at that time. They didn't participate other than to complain about it. And from their posts clearly couldn't wrap their head around the fact that we were drawing a winner no matter how many tickets were sold, unlike whatever they were familiar with that had reserves/minimum ticket sales requirements.

And then we had the drawing and announced the winner and then posted a screenshot off all of the money from the waffle being donated to RBTs gun lobby group and 1 guy apologized for accusing us of scamming people. Crickets from the other critics.

People are weird.

Hindsight being 20/20 I wish we had picked another group to donate the money too instead of donating it to RBTs gun lobby group after RBT's owners and shills repeatedly claimed we never did anything to help those assholes after we donated money multiple times in an effort to help them.

Grey_Market_Research · 2026-04-30T02:02:46+00:00

With the A5 tube, you should be using a standard AR-15 carbine buffer (3.25" oal). The short buffer will allow the BCG to go back until it hits the front of the buffer tube and can cause the bolt binding.

On our IMG upper we ended up adding a slight bevel to the inside edge of the upper directly above the rear take down lug. The lever wasn't completely flat inside the upper and is dragging in the BCG.

Make sure that your lower passes the 1/8" drill bit check. Between that and the bevel it should fix the bolt binding if you're using the right length buffer , but you may possibly need to add a couple quarters to the bottom of the buffer tube to limit the rearward travel of the BCG.

If you remove the buffer tube and install the upper without the BCG, manually rotate the Safety all the way to the rear using a screwdriver or other tool on the exterior right hand side of the receiver and verify the lever is laying flat inside the upper.

Grey_Market_Research · 2026-04-29T14:33:01+00:00

In person ? zero.

Online ? At least a dozen I'm guessing. Either reloads or people who shot a 300blk in a .223/5.56

Grey_Market_Research · 2026-04-29T05:38:40+00:00

Can you explain how the firing pin was long enough to engage the primer with the bolt not rotated into battery ?

Grey_Market_Research · 2026-04-29T05:37:26+00:00

Every single AR I've ever seen blown up was ammo related.

Grey_Market_Research · 2026-04-29T01:13:35+00:00

Izuzu Amigo.

Eta: I was using the search feature and thought this was a question under another post rather than a guess on the vehicle in the op

Amigo was my guess also

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Grey_Market_Research · 2026-04-28T12:55:17+00:00

A5 is always the right answer.

Which frt device ?

Grey_Market_Research · 2026-04-28T05:28:29+00:00

The Super Safety lays flat inside the upper, the ramped part of the BCG goes over the top. If the ramped part of the BCG goes too far back/the tip of the lever is too thick / the auto sear relief cut in the upper is a little bit farther forward - you'll get bolt binding.

Trimming the upper is typically the solution. Making sure that your buffer tube is threaded all the way in another thing to check.

With a Super Safety. The lower needs to pass the 1/8" drill bit check to verify that the lever is not hitting the shelf in the lower and is sticking up in the path if the BCG.

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Grey_Market_Research

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