Tag Archives: 12.7×42

Changing Springs and Buffers in My Beowulfs To Improve Reliability

Okay, so the last range trip went a lot better. The new Lancer L5AWM mags with Tromix followers worked great. The reliability on the pistol was coming along but not where I wanted it and the rifle was disappointing still but I knew what was going on.

7.5″ Beowulf Buffer Spring

My 7.5″ Beowulf pistol is running pretty well but I wanted to increase the forward force of the bolt carrier to strip the next round and chamber it. I was already running an H2 buffer but an other wise normal carbine spring. I upped my game to a Sprinco Red Extra Power Carbine buffer spring that they say is made with the “thumper” cartridges such as the .458 SOCOM, .450 Bushmaster, .50 Beowulf. I bought mine from Primary Arms.

The Mil-Spec Carbine Buffer Spring is on top. The Extra Power spring is on the bottom with one end painted red. That’s handy for knowing what spring is in the weapon at a glance.

I cleaned the pistol, lubed everything and installed the extra power spring and the H2 buffer that was in there. It definitely slammed home harder when I released the bolt.

When we go to the range next, I’ll be taking a standard carbine spring, an enhanced Sprinco spring and the carbine already has the extra power spring already installed. I’m also taking standard, H2 and H3 buffers with me.

Changed the Spring and the Buffer on my Full Size Beowulf Rifle

This rifle was built using an Alexander Arms DIY upper.

When we were shooting this, it had a hard time stripping the next round and chambering it. It dawned on me that they hydraulic buffer that I originally used wasn’t driving the bolt carrier forward hard enough. You see, a Hydraulic buffer has a piston inside that has a controlled leak down rate and, for whatever reason, it was dampening the stripping of the next round properly.

With carbine tubes, you have tons of sling and buffer options. Not so much on rifle length tubes. I did opt for a Geiselle Super 42 rifle-length buffer spring and a slightly heavier Expo Arms 5.4 oz rifle buffer –I bought both from Primary Arms.

Top: KynSHOT hydraulic buffer and Mil-Spec rifle-length buffer spring.
Bottom: Expo Arms 5.4oz buffer and Geiselle Super 42 Rifle-length buffer spring
The Kynshot buffer is very nicely made but I don’t think it’s the best choice for this application. I will save it for future projects.

When I cleaned the rifle prior to installing the new spring and buffer, the one surprising thing I found was that it was fairly dry. Why? I have no idea and this would have impacted functionality at the range also as I assumed I’d lubed it already before putting it away. Yet another example of my memory not being what it used to be.

Given that surprise, I went through and applied Super Lube oil and grease before installing the new Geiselle spring and Expo buffer. Afterwards, the action slammed home very easily.

I will take the hydraulic buffer with me back to the range for testing but am somewhat skeptical of it right now. The rifle is set for the next range visit at this point. Another Mil-Spec spring and buffer will be in the bag as well.

Conclusion

We have a ton of snow right now and I’ll have to wait to test my hypotheses. I expect that with the above changes, the two Beowulfs will run very well now.

I hope this helps you out!


Note, I have to buy all of my parts – nothing here was paid for by sponsors, etc. I do make a small amount if you click on an ad and buy something but that is it. You’re getting my real opinion on stuff.

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at info@roninsgrips.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.


A New .50 Beowulf Magazine Option: Lancers With Tromix Followers

I’m still experimenting with my .50 Beowulf (12.7x42mm) rifle and pistol that I have posted about previously. I wanted to find better magazine options – both in terms of looks and reliability – than my modified D&H aluminum magazines. I tried a number of different options and then happened on using Tromix followers in Lancer L5 Advanced Warfighters Magazines (AWM).

Tromix Followers

A small cottage industry has popped up of people 3D printing followers to center the various big bore cartridges in a given model of magazine. I’m still tinkering with some of the 3D printed models but during my surfing, I came across a machined aluminum model from Tromix Lead Delivery Systems. Tony Rumore and his colleagues at Tromix specialize in the .458 SOCOM round but they came up with a really slick follower design that would work with the really slick Lancer hybrid AWM Magazines.

I ordered in a few for testing and they are really nice. Here are a number of views for you:

Lancer Hybrid L5 AWM Magazines

So the above Tromix followers are made specifically to work with Lancer L5 5.56/.223 AWM magazines. The AWM considered a hybrid design because the feed lips are steel The lips can be a weak point in the design of some polymer magazines.

At any rate, the AWMs are really nice. You have a bunch of colors and capacities and are a very nicely made. They also have a number of capacities *but* for the Beowulf, stick to the 10 or 20 round magazines. The Tromix follower is relatively tall and can’t negotiate the curve in the 30s. It can be made to work with the 20s and I’ll detail that more in a moment. I have some thoughts on how to modify the Tromix follower to get it to work in a 30 but haven’t had the time to tinker with it yet.

The 10 round 5.56/.223 magazines can hold 3 Beowulf rounds without any tuning. The slight curve to the 20 round magazines can cause the follower to jam and we’ll cover how to address that next.

Tuning and Installing the Follower

Push the the button on the bottom of the follower and slide the base plate off. Note, the magazine spring will want shoot out so just be prepared to control the spring’s expansion.

This is an original Lancer follower stull attached to the spring. It’s really hard to get the assembly oriented wrong due to the design. The follower can only go into the magazine body one way. and the spring can only attach to the follower one way.
The spring can only fit into the Tromix follower one way also.
You then slide the assembly back into the magazine and slide the base plate back on. It is that easy.

The tuning required has to do with making the follower slide as easily as possible in the 20 round magazine. If you don’t then you are going to find that the Tromix follower jams inside vs. reliably pushing the cartridges upwards the way it should.

Now whether you do it before you install the spring or after, use a buffer and go all around the Tromix follower and make it nice and smooth. I used a 6″ buffing wheel with buffing compound. The reason I said you could either do it before or after is that I had already assembled four magazines before I realized I needed to do the polishing. Just rub off any buffing compound left behind. You’ll notice that the follower surface is far smoother to the touch than before.

I have used this 6″ Harbor Freight buffer a ton over the years as you can probably tell from the photo. It’s what I used along with some black/emory buffing compound to polish the followers.

The next step is to apply three coats of Teflon to the follower and the inside of the magazine body. I’d recommend using a dry lubricant inside a magazine body so it doesn’t attract dirt the way a liquid or grease would.

My preferred lubricant for inside a magazine body is Dupont’s Non-Stick Dry Film. It sprays on wet and leaves a layer of Teflon as the solvent evaporates off. Be sure to shake the bottle before spraying so the Teflon is floating in the can when you spray.

The trick I do is to use a heat gun to warm up the parts before I spray and then hit it with the spray lightly. I then warm it up again, let all of the solvent evaporate and then repeat for a total of three coats. I’ve hard far better luck getting a consistent thick layer of Teflon this way vs. trying to do it all in one spray.

The white dull look you see is the Teflon residue that will enable the follower to slide easier in the magazine body.

I spray the inside of the magazine body and all sides of the follower. Your goal is or there to be Teflon where ever the follower males contact with the magazine body. When everything is dry, reassemble each magazine.

Coat all four walls of the inside of the magazine body as well.

Testing

One quick comment – I do not recommend testing with live ammo. There are just too many things that can go wrong. I use A-Zoom 50 Beowulf Snap Caps to do my testing. They come in packs of two and I’d recommend having 4-8 rounds total for testing. Ideally, you’d like to load the whole mag you want to test so it really depends on what you plan on testing.

Get yourself 4-8 Snap Caps for testing. They are far safer than live rounds and hold up very well.

The Result

With the Tromix followers, the L5 AWM 10-round mags can hold three Beowulf rounds and the 20-round mags can hold seven. They are far, far more reliable than what I have been trying thus far.

The 10-round L5 AWM is on the bottom and the 20-round model is on top. You can see the big Beowulf rounds loaded to the capacity of each.
The weapon used first is this 7.5″ Beowulf pistol. Yeah, it bucks but I am trying to figure out the brake to use. There is a massive amount of unburned powder blowing out that pepper pot helical brake.
Target from 50 feet – rapid fire free hand. Yeah – feeding is way, way better.

The bottom line is that I am very happy with the pairing of the Tromix big bore follower with the Lancer L5 AWM 10- and 20-round magazines. I’ll experiment more to see if I can get the 30-round L5 AWMs to work but that is for another day.

I hope this helps.


Note, I have to buy all of my parts – nothing here was paid for by sponsors, etc. I do make a small amount if you click on an ad and buy something but that is it. You’re getting my real opinion on stuff.

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at info@roninsgrips.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.


What is the 12.7x42mm cartridge? Is it the same as .50 Beowulf?

The short answer is that they are the same thing. The bullet’s diameter is 0.50″ which is 12.7mm and the case length is 1.65″ or 42mm. The reason you see some vendors say they have something to sell in 12.7x42mm is they are trying to avoid a trademark problem with Alexander Arms. In other words, they are the same thing and people are trying to avoid a trademark infringement lawsuit.

Bill Alexander, of Alexander Arms, did all the engineering to bring to life both the round and the AR components to use it. He trademarked the term “.50 Beowulf”. As such, anybody who wants to sell something and refers to it as being for .50 Beowulf would need to get the permission and/or license the use of “.50 Beowulf” to avoid legal problems. So, a lot of vendors use the generic metric designation of 12.7×42 to avoid legal hassles.

With that said, bear in mind that not all engineering is equal. I have never had a problem with Alexander Arms parts but myself and others have had plenty of headaches with 12.7×42 components from budget AR vendors who haven’t done the engineering so buyer beware and research a vendor and their offering before you buy plus make sure they are reputable in general in case you need support.

So, short post this time. 12.7×42 and .50 Beowulf are the same round with different descriptions. but be cautious to check out vendors selling parts using the metric designation.


If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at info@roninsgrips.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.


My apologies but I have no way to filter out items that the vendors have sold out such as ammo. For example, most places sell out of the ammo fast but you should keep an eye on both Midway USA and going to Underwood Ammo directly – Underwood makes very good ammo by the way. I usually run Alexander Arms ammo but they are sold out most places and while you can place an order directly, you will need to wait quite a while for it to be made and shipped.