Weighting the P365/X/XL/SAS Grip Module

[CrisAnderson27]

So wonder if SIG might offer a Tungsten infused grip for the 365?

I'm not sure they would. That's usually a target pistol option. Adding weight for shooting stability in a carry gun...like we're doing here...is one thing...but a more fragile grip module, in a carry situation...would be counter productive. Imagine being in a circumstance where you're in fear for your life...you draw and your pistol gets dropped...and the grip module shatters. Bad stuff!

If people started using the 365's in competition I bet they would though.

 

[Alllen Bundy]

So wonder if SIG might offer a Tungsten infused grip for the 365?

Adding weight for shooting stability in a carry gun...like we're doing here...is one thing...but a more fragile grip module, in a carry situation...would be counter productive.

Therein lies the question: "Does adding tungsten powder to plastic resin actually have any effect on the strength of the molded part?" Adding particulates to plastic resin can sometimes increase it's molded strength.

I've seriously thought about adding weight to the muzzle end, but that would require a different holster. For now I'm just going to glue tungsten welding rod into the inside the grip module and call it good. That should close to 2 oz of weight, which is 1/3 more than I have now with the lead weight.

 

[CrisAnderson27]

Therein lies the question: "Does adding tungsten powder to plastic resin actually have any effect on the strength of the molded part?" Adding particulates to plastic resin can sometimes increase it's molded strength.

I've seriously thought about adding weight to the muzzle end, but that would require a different holster. For now I'm just going to glue tungsten welding rod into the inside the grip module and call it good. That should close to 2 oz of weight, which is 1/3 more than I have now with the lead weight.

Sig's TXG line isn't just resin/tungsten I believe. For the 320's they stated it's more brittle, so I based my commentary off of that.

I'll probably get some mold making done this week. I'm going to make a new backstrap weight with the tungsten rods and tungsten infused resin as the binder...since I'll have a mold to do it in instead of fighting with it inside the grip module lol.

I'll let you all know if/when I make any headway.

 

[Alllen Bundy]

Sig's TXG line isn't just resin/tungsten I believe. For the 320's they stated it's more brittle, so I based my commentary off of that.

I wonder what SIg means by "tungsten infused polymer." I'll bet that it is just tungsten powder mixed with plastic resin.

I just looked a the Sig webpage for the P320 TXG Grip Module. Then I got hit smack in the face with the price tag! YOUCH! If the tungsten infused polymer is actually more brittle, that is reason enough not to use it for a conceal carry self defense weapon, especially in Minnesota where the winter temperature makes plastic more brittle.

I've got 4 Ortlieb panniers on my bicycle. I've already broken 18 plastic buckles so far. If I try to actuate the buckles when the temperature is subzero the buckles start cracking. I can live with the buckles breaking. But If I dropped my P365X in cold weather and it cracked, I may not be able to live.

 

[Alllen Bundy]

I just ordered (20) - 1/16" OD pure tungsten welding rods and I was pondering about which epoxy to use to bond the tungsten rods together. JB Weld is my go to Epoxy when I don't worry about electrical characteristics and it does not need to be clear. JB Weld is allegedly infused with steel to improve it's strength. But that lower density steel is taking up room that could instead be used by higher density tungsten powder.

That being the case, I thought it might be better to add tungsten powder to a pure epoxy, such as Devcon 2-Ton epoxy, and it might result in a heavier epoxy mix. Tungsten is fairly inert so I won't need to worry about any unintended chemical interaction. The Devcon epoxy has a faster set up time than the JB Weld, so to ensure that the tungsten power will be well mixed, I'll mix the powder with each part of the epoxy before I mix the two epoxy parts together.

 

[DT Guy]

You guys know Wilson Combat just released grip modules with spaces for pre-made tungsten rods, right? Might be a much simpler solution...

https://shopwilsoncombat.com/GRIP-MODULE-WCP365-XL-NO-MANUAL-SAFETY-BLACK/productinfo/365XL-SB/

Larry

 

[CrisAnderson27]

I just ordered (20) - 1/16" OD pure tungsten welding rods and I was pondering about which epoxy to use to bond the tungsten rods together. JB Weld is my go to Epoxy when I don't worry about electrical characteristics and it does not need to be clear. JB Weld is allegedly infused with steel to improve it's strength. But that lower density steel is taking up room that could instead be used by higher density tungsten powder.

That being the case, I thought it might be better to add tungsten powder to a pure epoxy, such as Devcon 2-Ton epoxy, and it might result in a heavier epoxy mix. Tungsten is fairly inert so I won't need to worry about any unintended chemical interaction. The Devcon epoxy has a faster set up time than the JB Weld, so to ensure that the tungsten power will be well mixed, I'll mix the powder with each part of the epoxy before I mix the two epoxy parts together.

That is exactly my plan...I'm just using different epoxy lol.

You guys know Wilson Combat just released grip modules with spaces for pre-made tungsten rods, right? Might be a much simpler solution...

https://shopwilsoncombat.com/GRIP-MODULE-WCP365-XL-NO-MANUAL-SAFETY-BLACK/productinfo/365XL-SB/

Larry

I saw that yes. I've always heard good things about their grip modules. My problem with it is that..like all of the alloy modules...they are hideously ugly to me lol.

I've actually worked out a laser stipple package for my XL. I still have a lot of testing before I try it on a $40 grip module...but it should be cool.



The black is the burn path. It doesn't show the actual texture but gives an approximation. Guess we'll see!

 

[Alllen Bundy]

You guys know Wilson Combat just released grip modules with spaces for pre-made tungsten rods, right? Might be a much simpler solution...

The problem is that Wilson's grip weight kits only add 1.5 oz. I already have a 1.5 oz weight in my grip module. I want over 2.0 oz of grip weight. To do that I would need to grind or sand out the plastic holders for the tungsten rods in the Wilson grip module so that I could completely fill the area with 1/16" tungsten rods. I also don't like what Wilson has done with the inside edge of the mag well. They beveled out part of the inside rear of the lip that I need to help retain the tungsten rods, and it would also leave a gap between the mag well and the magazine floorplate.

It looks like Wilson made the beavertail even longer. I already sanded down the XL beavertail a bit to improve the draw.

The P365XL grip fits my hand like a glove as it is. I don't need the grip to be any wider. I would need to try one of their grips and be very impressed by the fit in my hand before I would consider one.

I don''t have much opinion of Wilson's stippling pattern one way or another. But the stock Sig stippling looks just fine the way it is. And my pistol will look stock to all, except those few with a very discerning eye. In fact, my pistol looks positively boring. If I'm ever involved in a self defense shooting I'll want the prosecutor to believe that my pistol is completely stock and boring. I don't need no steenking racing stripes on my self defense weapon.

But the Wilson grip module might be a great option for someone that needs a wider grip module and doesn't want to do any work to increase the grip weight.

 

[Alllen Bundy]

That is exactly my plan...I'm just using different epoxy lol.

GMTA! Which epoxy are you planning to use?

 

[CrisAnderson27]

GMTA! Which epoxy are you planning to use?

Right??

Since I'm also likely casting a weighted rail adapter, I wanted something with proven impact resistance. I chose Tough Cast 65D. For just the backstrap weight I'm certain Devcon will be just fine.

 

[CrisAnderson27]

GMTA! Which epoxy are you planning to use?

Oh, also....if that Devcon is anything like the epoxy I use to affix my knives into handles (JB Quick Clear), any additive is going to make it cure much, much more quickly. Just something to keep in mind. I've used powdered dyes, liquid dyes, and even metal powder to color my handle epoxy and the slowest halved the handling time, the longest wasn't far behind either.

 

[Alllen Bundy]

Since I'm also likely casting a weighted rail adapter, I wanted something with proven impact resistance. I chose Tough Cast 65D.

I concur that for a rail adapter the tungsten infused urethane would be a much better choice than epoxy.

For the grip weight I need to do some grinding on the tungsten rods in order to fit the maximum amount inside the recess inside the grip. But I don't see any practical way to then fit the ground pieces together perfectly in one gluing step inside the recess. So I am going to epoxy the stack of rods together and after curing I will grind the stack of rods to fit into the recess and then affix the stack of rods into the recess with urethane glue.

I'm still debating whether or not to add tungsten powder to the epoxy. I estimated that filling the voids between the rods would only increase the weight by about 7%.

I would be surprised if adding tungsten powder affected the curing time of epoxy, as tungsten is supposed to be fairly inert. But you never know until you try.

 

[CrisAnderson27]

I would be surprised if adding tungsten powder affected the curing time of epoxy, as tungsten is supposed to be fairly inert. But you never know until you try.

It's not a chemical reaction. I think it has more to do with oxygen or moisture introduced with the addition of the powder I can say though that with all of my iterations, adding even plastic powder (which I've done) accelerates the cure time dramatically.

 

[Alllen Bundy]

I bought a couple packages of 1/16" diameter pure tungsten TIG electrodes. The tungsten rods are too hard to cut with a hacksaw. I used a Dremel grinder with a cutoff wheel to cut the rods to length. The tungsten rods appear to have been ground to diameter and seemed to still be rough enough to glue as is, after wiping them down with 99.9% isopropyl alcohol.

I used JB Weld epoxy. But that is where things went wrong. I laid out a piece of plastic wrap over a flat granite tile. I applied epoxy to each rod and laid them in rows. The 1st row had 9 rods. I laid 8 rods on top of the first row of rods. The 3rd row had 7 rods and the 4th row had 4 rods. I lifted the plastic wrap at the sides and placed a steel block on each side to contain the rods in the 1st row. The plastic film prevented the epoxy from bonding to the steel blocks or the granite tile.

Unfortunately, the JB Weld Epoxy was just a bit too viscous and I didn't get all of the excess glue squished out from between the rods. You can see space between the rods that were not aligned correctly. This required considerably more grinding and sanding to make the weight fit into the handgrip. I wet ground and wet sanded the weight as I didn't want the epoxy to be overheated. I sanded the flat magazine side down to 1000 grit. It is quite smooth and shiny and should not offer much friction to a magazine being inserted.



I don't think adding tungsten powder to the epoxy is advisable as it would make it too viscous and also make it more difficult to squish out the excess epoxy. The next time I will use Devcon 2-Ton epoxy, as it is less viscous and it should be easier to squish out the excess epoxy so that the rods fit more closely together.

The weight is just a hair over 2.0 oz. The tungsten rods yielded about 33% more weight than the 1.5 oz lead weight that I previously used. Had I aligned the rods better, less grinding and sanding would the been required and the weight would have been at least 1/10 of an ounce heavier.

All things considered, this is an improvement over the lead weight in both additional weight and not needing to be concerned with lead rubbing off on the magazines. I will be gluing the weight into the grip module with JB Weld Plastic Bonder.

 

[Alllen Bundy]

The tungsten weight is now glued into place. The tungsten weight actually prevents severe misalignment of the magazine while you are inserting it into the magazine well. The tungsten surface is very smooth and nearly friction free.

Top View


Bottom View


The only downside appears to be the cost of the tungsten rods and the time and effort to glue the tungsten rods together and grind them to shape.

If you want to get really nitpicky you could complain that the tan color of the JB Weld Plastic Bonder contrasts too much against the black grip module. Of course now that I have just finished gluing the tungsten weight into the grip module I discovered that JB Weld also makes their Plastic Bonder in black! I'll use the black Plastic Bonder next time.

The balance feels good. No side to side floppy feeling when the magazine is near empty. Whenever I pick up the pistol the beavertail drives down into the web between my thumb and forefinger and I get a nice high grip every time I pick up the pistol no matter how many rounds are in the magazine.

I used $15.40 in tungsten rods, about $1.00 worth of glue, and about $3.00 worth of sandpaper. So just under $20 in materials for the project.

I would do this modification again, minus the mistakes.

 

[CrisAnderson27]

The tungsten weight is now glued into place. The tungsten weight actually prevents severe misalignment of the magazine while you are inserting it into the magazine well. The tungsten surface is very smooth and nearly friction free.

Top View
View attachment 1055605

Bottom View
View attachment 1055607

The only downside appears to be the cost of the tungsten rods and the time and effort to glue the tungsten rods together and grind them to shape.

If you want to get really nitpicky you could complain that the tan color of the JB Weld Plastic Bonder contrasts too much against the black grip module. Of course now that I have just finished gluing the tungsten weight into the grip module I discovered that JB Weld also makes their Plastic Bonder in black! I'll use the black Plastic Bonder next time.

The balance feels good. No side to side floppy feeling when the magazine is near empty. Whenever I pick up the pistol the beavertail drives down into the web between my thumb and forefinger and I get a nice high grip every time I pick up the pistol no matter how many rounds are in the magazine.

I used $15.40 in tungsten rods, about $1.00 worth of glue, and about $3.00 worth of sandpaper. So just under $20 in materials for the project.

I would do this modification again, minus the mistakes.

Excellent work you blasphemous heathen!! Youve successfully ruined your poor pistol for anything but range use! I'm shocked that the gods of "purposefully" designed ultra light EDC firearms haven't struck you down!!

More seriously lol...I'm glad you found time to finish your project!! I've had my hands crazy full with buying, setting up, and building an enclosure for a laser lol.



Out of curiosity, why didn't you use your plaster mold to help fit the tungsten/filler mix? That was my intent. I made a mold of the backstrap well, was going to convert that to a negative mold...then use that to make a perfect fit.

Btw, very beautiful and precise work. I hope mine turns out half that nice!

 

[Alllen Bundy]

Excellent work you blasphemous heathen!! Youve successfully ruined your poor pistol for anything but range use! I'm shocked that the gods of "purposefully" designed ultra light EDC firearms haven't struck you down!!

It's all your fault. You gave me the idea to use tungsten welding electrodes!

Out of curiosity, why didn't you use your plaster mold to help fit the tungsten/filler mix?

I thought that it would be nearly impossible to grind the rod tungsten rods first and then try to lay them perfectly into a mold. The most critical surface will be the one against the magazine. So I decided to lay the rods on a flat surface and build layers on top of the first layer.

I'm going to try to make a weight for my P365 grip module with the ends of the tungsten rods that I cut off. I've got an idea to use magnets on a steel plate to constrain the tungsten rods. Hopefully I can eliminate any space between the rods with this next build.

 

[CrisAnderson27]

It's all your fault. You gave me the idea to use tungsten welding electrodes!



I thought that it would be nearly impossible to grind the rod tungsten rods first and then try to lay them perfectly into a mold. The most critical surface will be the one against the magazine. So I decided to lay the rods on a flat surface and build layers on top of the first layer.

I'm going to try to make a weight for my P365 grip module with the ends of the tungsten rods that I cut off. I've got an idea to use magnets on a steel plate to constrain the tungsten rods. Hopefully I can eliminate any space between the rods with this next build.

Ahh, I see what you did. I like that idea...going to have to figure out how to incorporate it into how I'm going to do it lol. Excellent work my friend...truly.

 

[Alllen Bundy]

Partial success and then failure. Using the magnets to constrain the tungsten rods while gluing worked very well. There were almost no gaps between the tungsten rods. However, the Devcon 2-Ton epoxy is just NOT bonding well on the tungsten rods. Some of the rods broke loose while hand grinding the tungsten rods. I am going to separate the rods and glue them with JB Weld epoxy. I'm also wondering if a thin Super Glue might work.

I laid plastic down to keep the tungsten rods from sticking to the steel plate or the magnets. FYI, I used the steel cover of a hard disk drive enclosure. After I laid down the 1st row of 9 rods, I lifted the plastic at each side and moved a magnet underneath to hold the rods in place. The magnets are placed with one magnet North side up and the other with the pole South side down. With the magnet polarity oriented this way there is also attraction between the magnets which helps keep the rods held together.

After stacking the 3rd row of 7 tungsten rods, I added a tungsten rod between the magnet and the plastic sheet on each side, to make a full row of 9 rods, so that I could put downward pressure on the rods to squish out the excess epoxy. Then I added the last 4 rods.

I've got a process that seems to work well. I just need to use the correct adhesive.

 

[Alllen Bundy]

I removed all of the Devcon epoxy from the rods and glued them back together again with the grey JB Weld high strength epoxy. Unfortunately, I had already been grinding on the weight. As I suspected, it is nearly impossible to keep the ground rods aligned properly. You can see some of the misaligned rods in the photo. That said, the rods were still spaced closer together than my first try with the tungsten rods. All things considered the weight still turned out well and it is completely useable.

Using the magnets on a sheet of steel to contain the tungsten rods worked well. But this time I was able to find some very thin polyethylene film at Home Depot. It was the red plastic flag material that they use to tie onto overhanging loads. So this time the epoxy didn't stick to the plastic. The polyethylene film was also much easier to handle than plastic food wrap. The JB Weld epoxy bonded to the tungsten rods much better than the Devcon epoxy. JB Weld apparently also makes a clear high strength epoxy. I may try that the next time.

After grinding the weight into shape to fit into the grip module, the final weight is about 1-3/4 oz. That is 1/4 oz more than the weights for the Wilson Combat P365 grip module. One difference between the P365 and the P365XL grip modules is that at the bottom of the recess inside the grip module it is angled. So I had to grind a bevel to match. Also, the last 4 tungsten rods were just slightly short of optimum. But that is what I had leftover from making the grip weight for the P365XL grip module and the length difference wasn't enough to worry about.

Now I'm off to the store to by some black JB Weld Plastic Bonder to glue the weight into the grip module.

 

[Alllen Bundy]

I glued the grip weight in place using black JB Weld Plastic Bonder. I think that it looks much better than the tan colored Plastic Bonder. When I pried the lead weight from the grip module in order to install the tungsten weight, it took a lot of effort and severely bent the thick lead grip weight in the process of removing it. The JB Weld plastic bonder appears to be doing a very good job. I doubt that there is any real chance of the grip weight ever coming loose. The plastic bonder is also not as brittle as epoxy, and it won't react to the plastic like some epoxies can.

I didn't grind the face of this P365 grip weight as far as I did with the P365XL grip weight, partially because I didn't get the first layer of rods aligned correctly. You can see more of the grey JB weld exposed between the tungsten rods. The next time I will grind the face of the grip weight more than I did this time, but won't grind quite as much off of the face as I did with the first grip weight. I am also going to try using clear JB Weld high strength epoxy, as I think that it will look better than the grey epoxy.

The grinding and sanding of the grip weight face sets the epoxy lower than the face of the grip weight, so that the magazine will only contact the very smooth surface of the tungsten rods.

While neither of these grip weights are perfect, they are more than adequate for the task of improving the balance when only a few rounds are left. While the chances that I'll ever need to fire all 15 rds in a self defense situation are very small, it does give me comfort that I've done what I can to optimize this pistol.


Left side: 1.75 oz grip weight in P365 grip module. Right side: 2.0 oz grip weight in P365XL grip module.

 

[Alllen Bundy]

I now have a P365XL and I have discovered that with the unweighted grip module it is not only top heavy and floppy feeling like a P365, but it is also nose heavy when low on ammunition. Adding the 2 oz weighted grip module not only eliminates the floppy feeling, but it also shifts the balance so that it is ever so slightly rear heavy with only one round left in the chamber. Without the grip weight it is slightly annoying. With the 2 oz weight in the grip module it gives me the warm fuzzies.

I'm going to order more tungsten rod and weight the new XL grip module as before, but this time I'll be using the Black JB Weld Plastic Bonder to glue the weight in place so it looks nicer.

I am relegating my P365 to pocket carry and I'll be using my P365XL for fanny pack carry.