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Installed New M4 Hammer and Mag Tube


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Hi all,

Just thought I would share my experience from this weekend installing a FFT 7 rd Tube and Geissele hammer.

 

Hammer:

Easy job with the right .038” snap ring pliers (I used Blackhawk 1285) and SD’s writeup. Be careful with the tiny snap ring. You can deform it easily if you don’t go slow and take care. I had to tweak mine back into shape with a pair of needle nose pliers.Trigger creep has been reduced substantially. I didn’t expect much of a change with just a hammer swap. However, the pull is now much heavier than stock. On the upside the break is very crisp. As others have noted, when the gun is decocked and on safe, you CANNOT pull the bolt fully rearward. I am not sure how I feel about that. Also, it appears that the contact surfaces on the Geissele hammer are unfinished. Perhaps this is done for final gunsmith stoning? I think I am going to swap in a FFT hammer and see what happens. I chose the Geissele for longevity concerns but I am not sure about the tradeoffs.

 

 

Tube.

Also an easy job. It just requires patience. I got a $22 Wagner heat gun from Home Depot and heated the tube (after taking out the spring, follower and snap ring with channel lock 927 pliers) just forward of the handguard retainer for about 25 mins while a buddy held onto the receiver/stock with a pair of gloves. It twisted right off. I cleaned the threads with acetone (you don’t need much at all, I would get nail polish remover with acetone if I had to do it again) and called it a day. When I installed the FFT tube, I threaded it in a few turns and then put a dab of green loc tite on the threads and then screwed it in fully. Then I put another dab of green loc tite on the exposed threads to let it wick down to the other threads. I went with green as that is what the factory uses (although I have an H2O with red Loctite on the threads). The camo finish was unharmed.

 

Hope that helps someone here :)

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Good job on the install. I would recommend replacing the trigger spring if you deformed it. They're cheap and can be had at Brownells. I would stick with the Geissele hammer. Another member who has been thru the Benelli Armorer course indicated that Benelli advised against cocking the hammer when the safety is on. Supposedly it strains the trigger bushing.

 

I would recommend adding the FFT trigger and disconnector. You'll have the best of both worlds -- longevity in the hammer and a light creep-less trigger pull.

 

You'll have no issues with the magazine tube coming out on its own. The magazine cap actually keeps the magazine tube from unscrewing. I never even bothered to put locktite on my magazine tube since I like to pull the tube out for periodic deep cleanings.

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The FFT is good quality, but the Geissele is heat treated better. It shows less signage of deformation from use.

 

DSC00140_zpsb7bfb0fb.jpg~original

Open this in it's own window and it'll be more detailed. Deformation of the FFT hammer is similar to the OEM hammer.

 

DSC00146_zpsf18f7714.jpg~original

The sear contact point of the Geissele hammer is more refined and has a larger surface area relative to the FFT and OEM hammers.

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Good job on the install. I would recommend replacing the trigger spring if you deformed it. They're cheap and can be had at Brownells. I would stick with the Geissele hammer. Another member who has been thru the Benelli Armorer course indicated that Benelli advised against cocking the hammer when the safety is on. Supposedly it strains the trigger bushing.

 

I would recommend adding the FFT trigger and disconnector. You'll have the best of both worlds -- longevity in the hammer and a light creep-less trigger pull.

 

You'll have no issues with the magazine tube coming out on its own. The magazine cap actually keeps the magazine tube from unscrewing. I never even bothered to put locktite on my magazine tube since I like to pull the tube out for periodic deep cleanings.

 

Yeah I don't want to start drama with loctite. I was just giving my reasons :). I am quite OCD.

 

As far as the Geissele hammer is concerned, I think in order to unlock its true potential you need to have a smith stone the surfaces. There seems to be extra material to work with. I bet with some love all of the negatives would be resolved. I am too stubborn and impatient to do that so I am going to order a FFT hammer and be done with it :)

 

Oh and thanks again for your posts on how to this. I would have never done it myself otherwise.

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Another member who has been thru the Benelli Armorer course indicated that Benelli advised against cocking the hammer when the safety is on. Supposedly it strains the trigger bushing.

 

Sorry to hijack your thread, congrats on a job well done!

 

The above quote makes no sense to me... if you shouldn't cock the hammer when the safety is on; how do you chamber a shell? Certainly NOT with the safety OFF? Cycling the action will cock the hammer...

 

Maybe someone smarter than me can explain.

 

Thanks.

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Let me see if I can clear this up.

 

Generally, the Benelli's hammer should remain cocked at all times. Even during reassembly, your life is a lot easier when you reinstall the trigger assembly with the hammer already cocked. You should avoid the situation where the bolt is forward in battery with hammer decocked. What the armorers advocate is you should not try to pull the bolt to the rear with the safety on while the hammer is forward.

 

When the safety is engaged, the trigger is prevented from moving enough to release the hammer sear. So if you pull the bolt handle to the rear, the hammer will be forced hard enough the face of the disconnector. The trigger will be fixed in position and will not allow for any mechanical give. When the safety is disengaged, the actual trigger will move as well as the disconnector. I personally feel this is a poor design kind of like how you can't put a decocked AR15 on safe. The issue is exasperated by the use of the Geissele hammer.

 

I've found myself in situations with the M4 was hammer down and a live round in the chamber due to a malfunction. Now if I re-engaged the safety, and tried to pull the bolt to the rear to clear the stoppage, I'd encounter the issue the armorers advocate against. Now, if I cleared it while it was not on safe, I wouldn't experience any issue.

 

I'd recommend everyone play with the trigger group out of the M4 and see how it responds to these different scenarios. I find the design of the trigger group to be rather antiquated and lacking in many areas.

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Thanks for the further explanation.

 

Still makes little sense that a company so fearful of litigation puts out guns with 10 pound trigger pulls but instructs armorers that it's improper to load an un-cocked weapon with the safety on.

 

Interesting that there doesn't seem to be any touted improvements in their new Ethos trigger group.

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Still makes little sense that a company so fearful of litigation puts out guns with 10 pound trigger pulls but instructs armorers that it's improper to load an un-cocked weapon with the safety on.

 

My Benelli M4 with Geisssel Hammer breaks at 7.5# (Stock 7#)

Trigger Pulls from my other long guns

SIG 556R 4.5# with Shooting Sight trigger & Scorro Springs (Stock 8#)

FS2000 7.5# with Nue-Trigger (Stock 9.5#)

SCAR 17 3.5# with Geissel Super SCAR Trigger (Stock 6.25#)

PS90 7# with Stock Trigger

According to my Timney trigger pull gauge.

[ATTACH=CONFIG]2496[/ATTACH]

Edited by 00stormbringer
added stock trigger wieghts
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I installed an FFT hammer today. The edges at the top seem to have a slight chamfer to them and the finish seems soft.

nst3.jpg

Trigger pull is much better.

Still has the issue with retracting the bolt on safety when decocked like the Geissele unit.

At this point I am not sure what I am going to do. Maybe reinstall the factory hammer and put in an FFT disconnector . . .

Edited by 12508
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I am only worried about parts count while keeping factory characteristics.

That is why I am leaning towards adding the disconnector and going back to the factory hammer.

 

On a side note I drove an hour out to no man's land to test the mods and the land has been placed off limits for shooting.

Grrr.

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I also have the FFT Hammer installed, I think your concerns regarding not being able to pull back the bolt while the hammer is decocked and the safety is on, holds true with the stock hammer as well... I think this is the way the Benelli M4 functions in general and no hammer will make any significant difference. I could be mistaken, but I could swear my M4 functioned this way, prior to the FFT hammer as well as after and while it may seem unusual, like another poster stated, just a quirk that I think you get used to. Similar to the AR15 and the inability to safety while decocked.

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I also have the FFT Hammer installed, I think your concerns regarding not being able to pull back the bolt while the hammer is decocked and the safety is on, holds true with the stock hammer as well... I think this is the way the Benelli M4 functions in general and no hammer will make any significant difference. I could be mistaken, but I could swear my M4 functioned this way, prior to the FFT hammer as well as after and while it may seem unusual, like another poster stated, just a quirk that I think you get used to. Similar to the AR15 and the inability to safety while decocked.

 

I just tried that to a stock Benelli M4 and you are right! Thanks for the tip.

I will be happy with my FFT hammer now and stop worrying :)

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I just installed the Taran Tactical reduced power hammer spring in my Benelli M4. It reduced the trigger wieght from 7.5#s to 4.5#s with the Geissele hammer in place. I am going to have to wait until the weekend to see how it runs with various types of ammo.

[ATTACH=CONFIG]2511[/ATTACH]

 

Sweet. Good to know.

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