Oh just glueing my $1200 gun back together…

Discuss the FN Five-seveN line of pistols and accessories.

Moderator: blueorison

Post Reply
trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 26 Jul 2022, 14:21

So my frame is cracking significantly and I’ve read another post in the past where this happened in the same spot. FN denied their warranty claim because they modified the magazine spring and polished the sear :roll: . I’ve done that as well, placed an EA trigger, used an EFK barrel, a regular barrel with ea spring, a light on the rail, and a red dot. So plenty of reasons FN would deny my claim as well which is why I’m not attempting to ship my only gun away. And I’m not bothering to mod it back to stock because that would involve more work and money than my attempted solution; plastic weld glue.

I don’t notice any flex in it yet so hopefully it survives but I doubt it will. No more light is the only other change I’m making. Yes, I reload 40gr around 5.8 gr true blue so maybe the frame can’t handle that. About 10k rounds. I can say without a doubt I won’t be buying another. Maybe another frame but I don’t think that’s possible. I also don’t think the mk3 has been beefed up in that spot. I know the mk2 was but that’s what I’m glueing back together. Frustrating!

Image
Image
Image
Image
s gif

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 27 Jul 2022, 09:51

What light? This is the first I have seen of this in a MKII with the beefed up front frame.


Also next time reach out, I have this wicked ass, and HOLY fuck expensive carbon fiber epoxy resin I use for fixing FsN frames.
Most of the time I use it for USG rails that have come loose and un fucking gunsmiths who know what they are doing frame damage, most often from them forcing the hammer pack pins out and chewing up the rear of the frame.
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 27 Jul 2022, 09:53

And you are using the correctly lugged MKII compatible EFK barrel? YES I have to ask just to cover bases.
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Re: Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 27 Jul 2022, 10:39

panzermk2 wrote:
27 Jul 2022, 09:51
What light? This is the first I have seen of this in a MKII with the beefed up front frame.


Also next time reach out, I have this wicked ass, and HOLY fuck expensive carbon fiber epoxy resin I use for fixing FsN frames.
Most of the time I use it for USG rails that have come loose and un fucking gunsmiths who know what they are doing frame damage, most often from them forcing the hammer pack pins out and chewing up the rear of the frame.
It was the stream light tlr-1. You have actually seen this before: https://www.fnforum.net/threads/im-done ... -7.204618/

The glue i used is rated for 3770 psi. We shall see if that’s enough.

It’s hard to see from that second pic I originally posted but the crack is also between the two notches the barrel rides between as well as on the bottom of the posterior side near where the cam sits. That’s where I originally noticed the crack and I believe that developed before I ever installed the efk barrel. I’m not certain on the timing though.

I believe it’s the mk3 efk barrel. That was the only one listed on their site when I purchased it. I’m attaching another pic:

Image

I believe this is a design flaw in the weapon and I don’t think it’s appearing frequently because most people aren’t putting high round counts through it. I know you are an exception jay.

I don’t know a lot about gun smithing but it seems like the barrel catch spring is underpowered, too far back, or both. Clearly too much energy is being transferred to the plastic frame. At least under the conditions I’ve been shooting: 40gr, somewhat hot, accessories, etc.

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 27 Jul 2022, 14:19

WOW I did not realize it was the same gun/post.

I see a lot of stuff and can't always remember.

Yep MK2 barrel, you look for the small cut out above the large cut out on the lug.


The relief for the barrel return spring used to be in the frame and it was a weak spot. So they tripled the thickness of the rib and moved the relief to the barrel lug. A MUCH better designed.
I talk about the frame and barrel lug differences here,
https://youtu.be/Unzjsr_4VAg?t=1114

FYI For years now all EFK barrels have come with a 20 pound spring, matching EA's 20#, over the OEM 18.

Still sucks to see this, I have not seen this failure on a MK2 yet. That is not to say someone hasn't put a over slide scope mount on one and broken it off, it's just not something I have seen a lot of. Not to brag but most folks know after the have modded their pistols FNH's is just waiting to void their warranty so they end up with me to be fixed. N
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Re: Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 27 Jul 2022, 15:27

No worries, I figured it slipped your memory.

Yea I noticed efk’s spring was also slightly longer and thicker than yours(by about 3 thousandths). I didn’t have any way to measure tension but I’d imagine theirs is a little heavier unless it’s a different steel. Their finish was rough compared to yours so maybe it’s a matter of polished vs unpolished.

I also found it interesting that the shoulder bump in efk’s chamber is significantly smaller than the stock barrel(less pronounced).This can be easily seen looking down the chamber or at a fired case. Not sure why they did this.

Either way i would be surprised if 2 lbs of spring tension is the straw that broke the gun. Sped it up, sure, but I’d imagine it would happen regardless, on account of this occurring in a stock pistol spring as well.

I shot the gun today and had my best 5 group SD of 3fps so it’s not done yet but we will see. Still working on my load so hopefully I find it before the gun falls apart. I know you’re probably thinking why would I keep working on it after 3fps but I’m obsessive and hard to satisfy. Which is why I’m definitely not buying a replacement FN. Maybe the rock, but I’d like to hear more on its reliability and accuracy.

trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Re: Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 07 Aug 2022, 05:32

So plastic glue did not hold up. I removed it and put a ton of jb weld in there. So we will see if the jb weld is the key and I’ve designed the mk4 or it’s the mkay fuck this.

Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 08 Aug 2022, 12:46

JB might not hold up well. It's shear strength is an issue.
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
blueorison
Competition/Training Mod
Posts: 10672
Joined: 11 Apr 2009, 14:28
custom title: UT/EA Pistol Captain
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by blueorison » 11 Aug 2022, 11:32

The pictures aren't showing up; I wonder how the Mk3 will compare; but if they are using the same frame design on the front...
Never attribute to malice that which can be explained by stupidity.
The shooter will always matter more than the gear ever will.
Stop relying on others to do the work for you.
Shoot more, worry less.

trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Re: Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 12 Aug 2022, 12:44

blueorison wrote:
11 Aug 2022, 11:32
The pictures aren't showing up; I wonder how the Mk3 will compare; but if they are using the same frame design on the front...
Yea I wonder the same. I know jays video shows they beefed up the side frame by a mm or 2 but that’s not the point of failure here. It’s that polymer between front metal slide and the cam. Point of contact is the front of the slide on the polymer at full slide retraction.

Not sure about the pics, they show up for me on multiple devices. The jb weld started failing so it’s devcon next with some better polymer prep

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 08:37

They did thicken up that whole area inside and out. This is why the MRD won't even fit 1/4 of the way into a well formed MK2 holster.


I took more pics of that area the frame and caliper at same time. Give me some time to get them edited and up loaded
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 08:44

I can tell you this. Inside it's the same, and in a way they had to do it that way to use all the same working parts. Externally is where they beefed up that exact part of the frame MASSIVELY
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 09:43

Image
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 09:43

Image
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 09:44

Image
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Re: Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 15 Aug 2022, 10:40

panzermk2 wrote:
15 Aug 2022, 08:44
I can tell you this. Inside it's the same, and in a way they had to do it that way to use all the same working parts. Externally is where they beefed up that exact part of the frame MASSIVELY
thanks for the pics. i can't tell since the calipers are blocking it but it sounds like the polymer behind the slide rail in front is identical. honestly, they could have beefed that up further without changing the parts. probably not enough complaints and/or too much money to change. especially when dealing with such tight budget margins :roll:

the connection between the side of the inside frame and the polymer backstop for the slide is where it starts separating first. photo of my third salvage/beef up attempt:
Image
Image

i sanded everywhere the devcon contacts. sanded and tried to equalize the two front slide contact points as best as possible as well as taking a little off so it makes contact a little further back.

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 12:04

It is thicker externally and on the underside of that exact spot you are having issues with.

The row of rails picture, very first one left side. The underside of the frame extends forward well in the area under where the rail is at.
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 12:09

The side in that area where thickened also.

Image
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

User avatar
panzermk2
Forum Supporter
Posts: 12059
Joined: 19 Aug 2008, 15:51
Location: Around here it's more like what can we shoot through next.
Contact:

Re: Oh just glueing my $1200 gun back together…

Post by panzermk2 » 15 Aug 2022, 12:20

this pic shows how far it extends out now.

Image
Jay Wolf
Pr. Elite Ammunition

"Engineers, the oompa-loompas of science!"

Be'ein Tachbulot Yipol Am Veteshua Berov Yoetz
Image

trevorstuart24
Junior Member
Posts: 20
Joined: 31 Mar 2022, 13:48

Re: Oh just glueing my $1200 gun back together…

Post by trevorstuart24 » 15 Aug 2022, 12:36

my outer frame is totally fine. it's the plastic backstop inside that's detaching from the inside of the frame. so i'm curious whether the plastic backstop is any thicker longitudinally. i'm posting pics to show where it has cracked.

Image
Image

if i were to let it continue, theoretically that plastic backstop would crack off on top of the cam. i'd guess the force would then be isolated to the barrel spring stop and it's plastic backstop. maybe still work but likely cause that to start cracking. or the slide would retract so far that the slide wouldn't stay on it's front rail. none of this could be seen if the slide isn't off the gun.

Post Reply

Who is online

Users browsing this forum: No registered users and 14 guests