grottulf

5/8 would be a little too big on my pencil barrel. I'm considering drilling and re-tapping the comp to M14x1 or something like that... And do the same to my barrel.

Thanks for the advice, but I'm not sure I understood exactly how you did it. Do you happen to have a have pic of the pin and weld?

Ok. Most 9mm comps I've seen has been 1/2-28. But nevermind the pitch, it's the choice of diameter I think is strange... The thickness if the barrel will be under 0.06" with a 1/2" comp! The comp itself will strengthen the barrel, but there will be a substantial stress riser between the barrel and the comp.

How come 1/2x28 is the "standard" thread for 9mm comps? With so little material left, I feel like it'll snap right of, if I drop the gun... And if I'll pin and weld on a comp, how close to the bore do I dare to drill?

It is possible to get a permit for a shorter barrel in Sweden, if I compete in a sport that allows shorter barrels. In IPSC you're allowed to compete with a shorter barrel, but for some reason they don't give approvals for shorter barrels. (You must always have an approval from a sanctioned shooting association, when seeking permit for a gun. If it's not for hunting then it's easier, but then you are much more restricted in what you can get.) So I'd like to keep it at 16" for legal reasons. How you measure the length isn't really defined in the law here though. I interpret it like you guys, and think that pinning and welding a threaded comp would be ok. As I said in the first post, I was comptemplating buying a Brekke comp. But I'm leaning towards building one myself, with help from a friend. Instead of threading it, I'm thinking of making a shrink fit between the barrel and comp, and press it on. I'd also like to make it in aluminum to keep the weight down. But I don't think that would work with aluminum, since that expands more than steel when the temperature rises. Maybe I'll just bite the (9mm) bullet, and get a Brekke comp after all...

That's one of the reasons I'm considering alu. But keeping the weight down is more important to me since I'll probably make it 6" long. Do you mean that an alu-comp has a life span of 1500-2000 rounds in a 223? How about in a 9mm?

Thanks for the advice! I rarely clean the comp on my 223, so it'll probably take a while before I wear out a comp from cleaning, even if it's in alu...

Ah, I hadn't thought about that. Good to know! Sucks though, since I only shoot FMJs, and was thinking about making a an aluminum comp...

What difference does the bullet do?

I've realized that drilling out the rifling is not a realistic option, due to the surface hardening of a barrel... At least not as deep as I wanted to go. I spoke with a friend who is truly awesome with both a mill and a lathe. He works professionally with them and does custom work on a daily basis. (I have both mill and lathe myself, but I really suck at using them ) As we discussed it, we came to the conclusion that it would be better to cut the barrel at 10", and shrink fit a tube over the barrel. I've also abandoned the idea of porting where there is rifling, due to the risk of getting burrs. But I could make the extension with a smaller inner diameter at the beginning, to get better effect from the comp holes, and with a larger ID at the muzzle to avoid unnecessary weight and minimize the risk of contact with the bullet. But now when I examine the pictures of the Taccom super feed 10/16 barrel, I realize that's probably exactly how you made that...? So I realize I'm trying to reinvent the wheel here. It sucks that I can't get a hold of those barrels on this side of the pond ☹

Thanks a lot for the input! I really value it. My original plan was actually to build a AR9 with taccom components (I emailed you about it last summer), but since I couldn't get my hands on that here in Sweden, I went with a FM instead. Too bad about the US export restrictions Do you mean that the sweetspot is centering the ports at 10", or placing the ports after 10"? (like with a 10" barrel) And do you have any advice on what diameter I need to use when drilling out the rifling? I was thinking about drilling with a 10mm drill first (maybe 4-5" deep). But is there a risk that the bullet touches the barrel because of the recoil? Should I drill the last section (maybe 3" deep) with a larger diameter (12mm?)...? The reason for not going 12mm all the way, is I'm thinking about drilling a few holes after the rifling as well (more like a comp than a porting) And I think those holes would be more effective with more goods thickness...? And do you have any input on the diameter for the port holes? I'm thinking about drilling (or actually milling to avoid burrs) 5mm holes... Is there a risk that I end up with a barrel that overcompensates and actually dips on recoil, if I drill to many ports and comp holes...? I should mention that I'm no fan of handloading, so I want it to work well and keep a PF of at least 125 with standard pistol ammo. Preferably 115gr, but heavier bullets is ok as long as it's easy obtainable standard ammo. I know I'm probably over analyzing everything...

I have a FM9 with a 16" barrel and a threaded comp. I know the comp isn't doing much good that far from the chamber. So I thought about shortening the barrel to 10" and pin and weld on a Brekke 6" comp. But I would like to try a little cheaper route. Partly because the prices over here are about twice what they are in the US. But also because it's fun to do it yourself... So I was thinking about porting the barrel at about 6" from the muzzle. But I'm a little concerned that I will loose too much bullet speed... So I'm thinking about drilling out the last 4" of rifling in the barrel, with a 10mm drill, so it won't loose as much speed. The OD of the barrel is only 16mm, With gives a thickness of about 3.5mm. so I think several small holes would be better than a few large holes at directing the gases straight up. Has anyone here tried anything similar? Any thoughts?

FM didn't have the required export permits, so Brownells will ship the bolt. But unfortunately, at the moment they can't export any gunparts that requires a permit over here, due to corona... So it might take a while until I get it... But I'm curious about how deep the pockets depth is in the revised FM-bolt. I asked them, but didn't get any answer. Does anyone here have one? If so, could you please measure the depth for me?

I emailed Foxtrot Mike about it, and they were very forthcoming. They will to ship a new revised bolt to me. Great customer support!

Now I've removed the barrel to get a correct measurement. I wasn't so far off in my estimation... The headspace seems to be 0.46mm (.01811") too long... Here are the numbers: Length of my 9mm ammo casing: 19.03mm (.7492") Bolt recess: 3.34 mm (.1315") Chamber depth: 16.15mm (.6358") Total headspace: 3.34+16.15= 19.49mm (.7673") Difference in length between ammo and headspace: 0.46mm (.01811") Protrusion firing pin: 0.75mm (.02953") In other words the firing pin does only poke 0.29mm (.01142") into the primer... Can anyone tell me what part or parts are out of spec? Thanks!

I've done some more research, and I'm pretty sure it's a headspace issue. I estimate that there is roughly 0.5mm (.02") of play between the bolt and the bottom of the casing as it is now, and that can't be good. I will measure both the chamber and bolt recess (and casings) tonight to see which one is out of spec...

Thanks, they are a little over my budget though. I'll try to make do with a polished stock trigger, at least to begin with.

Could it be a headspace issue? I don't have a feeler gauge that is narrow enough to get in there, but I'm thinking about narrowing one down so it fits... Or is there a better way to measure that?

Yes, as I said, I bent it to stiffen it up. Not to soften the pull, as most people do It sits on top of the trigger pin. But it was tricky to get it there, when it was bent so much.

I just got a new completely stock Foxtrot Mike FM9B. And I'm having some problems with light primer strikes. The ammo I'm using is known to have hard primers (Swedish military ammo), but they work very reliably in my Glocks, and other duty-type handguns. I'm pretty new to AR9s though. So I was thinking maybe they are picky about primers due to their firing pin spring...? I have tried bending the hammer spring as much as I could, to increase the power of the strike, but it wasn't enough. The firing pin looks good and runs freely in it's bore Any thoughts?

A second slightly revised version of the Tigris XR12 Pro has reached the Swedish dealers now. Some of the visible changes are a larger magwell, longer handguard, new stock, ambi mag release. I've ordered one of them, but it will probably take 5-6 weeks before I get the permit for it. I'll be back with my first impressions when I get it... Skickat från min SM-G950F via Tapatalk

Great videos! Thanks for sharing your knowledge and insight! Sorry if it's already been covered, but what's the specs on your PCC rifle? It seems to shot really flat [emoji106] Skickat från min SM-G950F via Tapatalk

Yeah, it would probably not take many lessons before one surpassed the language skills of Google translate...[emoji849] I've managed to turn on cc on my desktop computer now, so I can watch it there. But it doesn't work in the android app for some reason. Skickat från min SM-G950F via Tapatalk

Thanks, I didn't know of that function. But I only managed to get Russian text... I have activated Google texting in the settings for my account and choose Swedish. But I only get the option for Russian autogenerated subtitles, when I choose settings for the video... Any ideas? Skickat från min SM-G950F via Tapatalk

There are a couple russian videos about it on youtube. Too bad I can't understand a word of it... Anyone here understands Russian, and can give a lowdown on what he says? This is an initial review, if I understand correctly: And this is a follow up after 2000 rounds: Apparantly there are already aftermarket comps, Magwells and handguards for them. Skickat från min SM-G950F via Tapatalk