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I’ve come around on the Remington R51. In my initial review in 2014 I wasn’t a fan, and the gun didn’t seem ready for prime time. Two years later, Remington had worked out the bugs earning the re-reviewed gun a four star rating.

I kept the handgun used in that review and have been shooting it ever since and I think I finally found the thing that takes this 9mm pistol from a four star gun to a five star gun, something that should have been a factory option: a threaded barrel.

When I spoke to Remington about their new R51 product lo those many years ago, one thing I repeatedly pointed out was that this would be an amazing suppressor host. The Pedersen-designed action means that the barrel is fixed in place. Instead of a Browning-style tilting barrel acting as a short stroke piston during the recoil cycle like pretty much everything else on the market in its class, the breech block itself performs that function. It’s pretty nifty.

The net result is that when you want to add a can to the gun you don’t need a Neilsen device (or “recoil booster”). Instead the can threads directly onto the barrel and remains fixed in place.

That means less muss and fuss transitioning between handguns and pistol caliber long guns for those who have threads on both. Less cleaning required between range trips. And lower chance of failure due to easier designed mechanisms. It’s a huge win all around.

At the time Remington seemed more interested in pushing this as their latest concealed carry handgun, positioning it almost as a modern HK P7. When the initial reviews and subsequent controversy caused the R51 to lose favor, it seemed like Remington would much rather have buried the project than improved it. But a few hardcore fans, like the folks at DangerCo, have been hard at work trying to bring those missing features to the market.

The DangerCo R51 threaded barrel starts life as a factory-standard R51 barrel, one that (if installed) would be flush with the front of the slide. That’s obviously no good for installing threads.

DangerCo adds a barrel extension to the front and threads that instead, adding about an inch-and-a-half to the overall length of the gun. Then they slap a thread protector on the front and ship it out to the customer.

In the video above, I go through the process of field-stripping an R51. As you can see, it’s not all that fun or easy. To install the threaded barrel you’ll need to go through the same process and swap out the old barrel for your new one, but there’s a catch.

The threads on the new barrel will make this process excruciatingly annoying. For me, at least, the threads kept catching on the slide and binding up. It was only after a good half hour of cursing John Pedersen’s existence that it finally slipped into place.

Once it was installed it was completely worth the time, effort, and money.

The fit and finish of the barrel is great. Which, considering that it’s pretty much an original Remington product with some tinkering, makes sense. As for the threading, the pitch is a solid and concentric 1/2×28.

Something interesting to note about the Remington R51, and the AAC Ti-Rant 9mm can specifically, is that the sights just barely clear the top of the can.

Normally you’d need suppressor-height sights on your gun which are significantly taller than the normal variety to get a clear sight picture, since silencers tend to be particularly thicc bois. In this case the chunky slide geometry of the R51 combined with the svelte profile of the Ti-Rant make for a sight picture that is legitimately useful.

The real beauty of this set-up comes when you’re out on the range. In practice there were no issues whatsoever when adding the can to the front of the gun, not one single added malfunction due to over gassing or any of the other ill effects that usually come with a silencer.

All that you get is a beautiful and easy-shooting handgun that not only looks like something straight out of James Bond (but in a real caliber instead of .380 ACP) but also is downright enjoyable.

The sound suppression is exceptional. And due to the Pedersen action, I actually think it’s quieter than a GLOCK with a similar set-up. Plus, as previously discussed, there’s no booster in the can to induce failures (or to clean after the trip). Easy as pie.

I liked the R51. The second generation, at least. But most of the time it spent its life sitting in the safe next to its original 1930’s era Remington 51 grandpappy. It was kind of a curiosity.

This one part, this one simple design change, has elevated the firearm from “hey look at this weird thing” status to the one firearm that I always bring to the range no matter what. It’s now officially the most fun thing I have in my gun safe, and that includes a suppressed MP5K.

Specifications: DangerCo Threaded Barrel for Remington R51

MSRP $125

Rating (out of five stars):

Overall * * * * *
If you own a pistol suppressor, this one item will turn the R51 into one of the most eligible suppressor hosts on the market. And consider this: a brand new R51 from Bud’s plus this aftermarket barrel will STILL be cheaper than a current generation GLOCK.

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  1. A threaded barrel for a gun that 5 people actually purchased and 3 of them are still willing to shoot…

    • Ah, yes, the fabled threaded barrel. I’ve heard about these, but due to the fact CA outlawed these long ago, I’ve never actually seen one. (snort)

      I think it’s because our Dear Leaders in Sacramento tell us pleebs that the threads allow a for the addition of deadly accessories, making a deadly firearm even more deadly-er. And therefore even more illegal-er.

      • I haz a question (really); if threaded barrel are illegal there, would a collet-based muzzle device attachment be kosher in Kali? I mean, you wouldn’t *attach* the device while you’re there, but you’d have the ability to put on brakes/etc when you are visiting a place where it’s legal or you wouldn’t get caught.

        • Good question. I’m not quite sure where the legal line in the sand is for this, but one of my ARs has a “noise brake” on the end, though it’s pinned to the barrel. If I recall another conversation correctly, I believe an accessory has to be “permanently” attached, or at least not easily removable. But then again, our good friend The Daily Shooter (who just moved last week to NV after living in CA his entire life) recently did a review on a collet-based noise brake.

          Most of my gun-owning friends – including several LEOs – are simply adopting a “don’t talk about Fight Club” mentality. When a group of us went out to the desert recently, several guns came out of the cases that wouldn’t even raise an eyebrow anywhere else, but are now illegal in CA, or at least questionable due to the labyrinthine maze of laws we have. Nobody said a word about them after we packed up at the end of the day.

    • Been very pleased with mine. Easy to carry, easy to conceal, fun to shoot at the range, very reliable, more accurate than me. Picked it up with a rebate-I think I’ve got $140 in it. Wish the caliber started with a ‘4’.The thinness of the grip took some time for me to get used to.

    • Love my Gen 2 Model R51. It eats everything I put through it, no failures whatsoever. It’s my new EDC 9mm, and I’ll probably grab a a second one in the Smoke finish while they’re still cheap. (First one was just over $200 earlier this year at Mill’s Fleet Farm) Dangerco not only makes threaded barrels, they also make 1911-style aluminum replacement triggers that take care of that trigger side-to-side wobble.

  2. Good review. I want to pick up an R-51 but am afraid of the gen 1 product. I like the look, fit and finish but can’t see to pull the proverbial trigger. This review might take me over my initial fear.

  3. The suppressor may be a dandy but considering the pile known as the Remington R 51,isn’t that a bit like a silk purse for a sows ear.

    I hear or read that Remington is down for summer vacation,no great loss with the quality assurance they have been producing as of the past 8 to 10 years or so.

    • If it makes you feel better, Remington fired everyone involved in the first production batch at the old Para USA plant. Maybe if they’d waited until after the gun was made to break the bad news to all the employees, the guns might have turned out better…

    • Like takin a dump in a silk sock.

      I can’t remember how all those go, but there was a series of them back in the day.

  4. I have an R51. It is true, it isn’t my first choice as a carry pistol, that role is taken by my Browning 1911-380. However, it is a reliable and accurate pistol. The only real negative thing I can mention is that in large part due to the low bore axis, I tend to get a bit of slide bite. That and the takedown is very unusual.

    Here is the odd part, I have had several friends wives really take to it due to the very slim profile. In all, as an owner, I consider it to be good, not great, but good. That is the same rating, or maybe a little better, that I give my Glock 42.

    I also have a Danger Co barrel, it is first rate.

    • Is yours the post-recall model? I have a preemie, and the disconnector flat broke around the 600rnd mark…which made me sad because I really like shooting it (super fast gun). The guns are like 250$ on GB these days, so I’m considering getting a second, so the first can undergo surgical experiments at the hands of Gunsmith Mengele (me).

      Anyone find it odd that the author would refer to the R51` slide as “chunky?” I also find it disappointing the thread protector on this product was not turned to the same diameter as the barrel, specifically to make disassembly a little easier (I do understand how paper-thin it’d be, though). I wonder if you could do interrupted threads, to smooth the top/bottom surfaces for easier assembly, with the muzzle device still torqued against the shoulder. People that complain about the R51 takedown usually have only done it a couple times. It’s different for sure, but it’s hardly torture. Getting the bolt carrier back in a PKM is more annoying, to me.

  5. I love the look of the R51, I hated the side to side play in the trigger, just seemed weird and didn’t inspire confidence. Mine never malfunctioned with brass case so there’s that.

    More fun than an MP5K, c’mon!

  6. Is Remington still making the R51?

    I see that Bass Pro no longer lists it as a stock or orderable item and Cabelas only has the laser pointer version.

  7. I have an R51. Bought it (post recall) because it was super cheap, and I like weird stuff.

    It has been reliable and accurate, and if it weren’t such a true pain in the ass to strip and clean, I’d carry it.

    Been waiting for DangerCo to do another run of the threaded barrels.

    • Okay, you’re the second guy to say the Gen2’s are reliable…I’m starting to hope again. How are you lubing (or not)? I found I had to use teflon grease to get any sort of reliability from mine, and even then I had to police burrs from peening on the cam surfaces with a file. But if it’s able to hold up to even moderate use, then for ~200$ that’s a big novelty bang for the buck. I had a ton of cool ideas for the piece I wanted to explore, like a safety-lever-activated aiming laser, or a 22TCM conversion (there’s room in both slide and magwell for it). The barrels themselves are so simple (compared to a Browning) it’s almost not worth the trouble of making an attachment like this.

      • I don’t lube it in any special way, just a drop in obvious bearing surfaces like any other pistol.

        Now I’m thinking about getting another one to keep nice.

  8. Question on the R51 itself –

    I’m seeing these more and more in the used gun cases, how can you tell the old worthless ones from the second generation ones?

    Is there a serial number cutoff from old to new?

    • The new-est ones have Alabamer as the home town vs. Charlotte, NC. A lot of old parts & frames did make it to Bamer with the old markings, though. IIRC, there’s also an extra pin inside frame rails for the new-style pivoting (vs. the old sliding) disconnector, but I don’t think it’s externally visible.

    • Jud the sites are “staked” and it has a Huntsville manufacturer its a gen 2. Some Charlette r51’s are second gen and those will have staked sites too. If the sites are not staked, its a first gen.

    • Gen 2 guns were marked for both locations after the redesign as they transitioned to the Alabama factory. You can have a Gen 2 R51 that’s stamped either Charlotte, NC *or* Huntsville, AL. The best way to tell you have a Gen 2 gun is that the R51 logo will be inside the scalloped area next to the ejection port, vs. lower and further back on the slide for the older version. BTW, the sights on my Gen 2 Charlotte NC R51 were not staked. They have allen screws, which I then used to swap out for Trijicon night sights.

  9. Is Nick back to writing? I hope so!

    I really wanted an R51 when I saw them. Mostly for the space gun aspect. Then they came out and wow… For my rotating barrel goodness I have a Grand Power Q100. I love that pistol. Shoots very flat and a decent trigger. It was also inexpensive for what you get. Now, mags are a bit pricey.

  10. Nick, any issues with first couple rounds nosediving into mag lip?

    Would be cool to see a vid of it suppressed. A phone slomo with a suppressed browning action would be really helpful to illustrate what you’re describing. Two shooters alternating shots. Might make this more compelling given the rep.

  11. I was one of the original AAC employees dating back to 1998. I lasted through the sale of AAC to Remington, and was there designing stuff until a couple of months ago. We played around with the R51 at AAC right after they came out. There were no threaded barrels, so we extended and threaded a couple in the AAC machine shop. We shot it with Remington L9MM9 147 grain ball through a locked out Ti-Rant 9 in the AAC live fire trailer (a tractor trailer that had been armored, ventilated, and had sound absorbing foam added to the walls). It was hands-down the quietest suppressed 9mm I and every other AAC guy at the time had ever fired or heard. It was actually pleasant to shoot in such a confined space packed with other people, which should have been a worst case scenario situation. Given their cost at this point, it’s worth picking up an R51 to have something that is so quiet in 9mm. FWIW, I have a gen 2 gun with a factory threaded barrel that has been 100% reliable, and extremely pleasant to shoot suppressed.

    • AAC? Advanced Armament Corp? I absolutely love my .300 BLK AR pistol. I think the .300 BLK is the perfect AR caliber, as it provides a .30 cal punch with the loadout capability of 5.56.

    • Mike, I read a post you made about the quiet R51 some years ago, probably on ST. I picked up a Gen 2 and a Dangerco barrel and it is slick with a Poseidon. Oddly, removing the spring from the booster and adding the fixed barrel spacer to my ancient SWR Shadow 9 doesn’t cycle on the R51. Put the spring back in and the combo runs fine. Always enjoyed reading your posts, hope you landed well after departing AAC.

  12. I bought a gen. 2 R51 a little over a year ago and it has never gone more then a couple mags of ammo without a stoppage of some sort. Doesn’t matter what ammo i use.
    Sent it back for service,changed the polymer extractor spring. It did a little better for awhile.
    Now you can’t pull the slide back on a full magazine.
    Really like the feel of the gun, wish it would work.
    It’s not even a good range toy now, so in the safe it sits.

  13. +1 to R51, DangerCo barrel, and suppressor. With 147 gr ammunition, this thing is so quiet the only noise are the bullets bouncing off stuff down range.

    The DangerCo barrel and a tri-lug adapter makes a good companion to a MP5K as the same suppressor can move between those two firearms.

    The reason to have a R51 in my opinion is a niche. It would not replace a traditional, proven pistol, such as a Glock or CZ75 with a R51. On the other hand, the sliding block system is a good fit for shooting suppressed. The 2nd Gen R51 pistol itself does not have a problem with reliability, it is the magazine. Remington screwed the magazine up badly. To make the pistol reliable, I had to modify my magazines – actually several iterations of experiments until I landed somewhere that works reliable.

  14. This is a very informative read. I have found I have a real early Gen II R-51; I have the Charlotte, NC manufacturer address. There are some other pieces of information I am going to have to read and compare to see where I stand in the list of changes. My rear sight has an allen head screw, but my front sight is in a dove tail only.

    As to shootability, I have no complaints. I think I had a function problem for a few rounds initially, but none in the last 100 plus rounds. It is a bear to take down. I used a small vice grip with tape on the jaws to hold the barrel out so I could pull the take down piece out. Dam*near the same way putting it back together. It has gotten somewhat easier with each additional take down along the way.
    I really do like the pistol. I have the RP9 which is very easy to shoot. The extra weight makes it a good shooter, but not for EDC. I leave it at the house somewhere, long with my SS R1 .45 cal. Yeah, I am an old guy who has grown up shooting Remington. They work OK for me.

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