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7.62MM Firearms Trigger Group Evaluation

This is a discussion on 7.62MM Firearms Trigger Group Evaluation within the The M14 forums, part of the M14 M1A Forum category; I received the trigger group from 762MM Firearms. The more I see about this company, the more I like. The following are my impressions and ...


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Old January 25th, 2011, 10:45 AM   #1
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7.62MM Firearms Trigger Group Evaluation

I received the trigger group from 762MM Firearms. The more I see about this company, the more I like.
The following are my impressions and the best evaluation I can give. I have had some time now to
fiddle with it for several days, and more importantly, to put some rounds downrange with it. That tells the true story.


The following pic shows the issue Jon brought to their attention of the hammer travel during primary cocking.
Problem solved within 24 hours by 762MM. The bolt is larger in the rear and primary is the term I will use for the beginning
of the cocking process. This is the where the hammer should be, in relation to the housing, while primary contact of the bolt is
happening.

The next pic shows the same thing from the perspective of the trigger to hammer relationship, at the same time. Once again,
this is now corrected.

Here is another of the issues Jon found in his review, the contacting of the hammer spring housing, with the hammer, when in the
same position as above pics, primary cocking. Again problem solved, I was able to get a .004 feeler guage between the two, in this
position.

Another issue, the burrs at the safety spring fitment location, now solved.


Thanks again to Jon for mapping out and locating previous problems, making my job a snap.
Here is the reason the safety rode to the opposite side of the relief hole, than other G.I.'s that he compared with
The inside radius turn at the 90 degrees, as it clears the housing bottom inside, note the thinner G.I. safety. This has no adverse
affect on function, and is on the thicker side of my prints as allowed by the military.
Another point of interest is the nailset punch I used to stand them with. Notice the 762MM has slipped up on the knurled
surface of the punch, and the HC G.I. will not, indicating the hole is larger in the762MM. Also no affect on function,
as the rest of the entire safety I examined was on the large side of the blueprint, having more metal surrounding the lock hole,
and overall thicker.

TRW comparison pics, you be the judge. Notice the wide moon shape transition from the flat behind the mag catch on both,
several other examples I checked, including SA,WIN,and HR, had much less of this cut done as wide. This shows great attention to detail by 762MM.

Beefy at the top.

Beefy at the rear.

Trigger comparisons

Installed in SAI June 2009 model

Installed, primary cocking, Note: proper hammer hook location and bolt position.

Installed, full cocking.Note: bolt position and relieved hook position due to thinner
bolt body middle, again, now corrected.

Installed, Fired hammer position.

A few more comparison shots.

Now, here are some interesting shots that everyone should check on their rifles.
This is after the rifle is fired, and the trigger is still held back.Note: the primary engagement
of the sear to the hammers rear hooks. Correct and much needed safety check for all.
Actually in this sense of the proper terminology, the sear is working as the disconnect.
But I am not about to get into a fight with Uncle Sam....Gus Grin...The top of the trigger on the
M14 is the actual sear.

Here is the trigger being released to just about the point of firing.
Note : The proper secondary engagement relationship, of the front hammer hooks
and the trigger, about to take over.

Now that I have addressed all of Jon's findings, here are some of my own findings.
First off, I would like to thank Hawk, because I asked for special permission to go pic heavy on this,
and we both felt that the success of a new manufacturer of G.I. quality parts, is paramount,
and important to the entire membership.

I am retired and have a lot of time, so guess how I spend it ? Working and studying on M14 Parts and rifles.
I study them for hours on end sometimes, and am in the process of writing a book about the differences
from maker to maker, and how to tell them apart, so I know a good part when I see one. Upon first receiving the
trigger group from 762MM, I noticed right off that the finish was very close to G.I. originals.

I then set about fast finding, if the issues Jon found were still there, or had been fixed. After being satisfied
about those, I set about looking over the rest of it and did many part comparisons with all G.I. makers parts.
My findings are that 762MM always goes to the top end of the print on dimensions, and to me, thats a good thing.
The trigger housing pads were a full .010 thicker than all G.I. I checked, and I really like the look and heft of it.
You may say, won't that affect lock-up ? No is the answer, I checked the measurements on all the others from the top of the
housing, to the inside bottom of the pads, all were 1.722 and so was 762MM's. The rear pad was a full .003 thicker, and once again,
on the bottom side so as not to change lock-up. At this point in the reviewing process I go through, I noticed the pin for the mag catch
had a slight hang to it, allowing it to rub the trigger guard. A quick tap with a center punch finished seating it flush,... no biggy.

Disassembly was a snap and had no problems reassembling several times. This is one quick way to find problems. Tear it apart, put it together, ..
repeat, over and over, is how I do it. If they give you trouble, it is a good indication something is off.

The stripped housing looked good and had similar machining marks as do all G.I. housings, albeit a little rougher on the outside shooters left,
it has no affect on function and will rarely be seen inside the rifle. Personally, I like the look and have asked Chris not to
change anything about it when he sends something. I raised hell because they changed their parkerizing from the original, that had machining
marks showing on receivers, and my first one had that original Garand Green look.

Hammer comparisons yielded only a couple remarkable differences, but again, all within print specs and having no affect on functioning.
Overall height of the comparisons showed the 762MM to be .003 taller, once again top of the spec line, but the 60 degree concave facet on the top
of the hammer for bolt cocking, was relieved properly and appeared larger than the comparitors in area, as it should for working with larger material specs.

Hammer hooks and design: I found the hammer hooks to be exactly .0015 longer front and rear from the comparison items. The hooks all had the proper
radius turns for aiding in cocking against the top of the trigger and front of the sear. Bevels at these locations were the proper angles as well,
and the let off and creep travel were approximately the same as random others checked, with the exception of the newer feel, taken into consideration.
The example I received had a crisp but smooth release at exactly 5.4 lbs. I like mine a bit lighter and will take this one down a pound or so.
As previously shown in the photographs, the safety issues are all taken care of for disconnect functioning.

Cocking arm at the top left of the hammer compared excellent with all others checked and had proper angled cuts made. Length ,width and height
were unremarkable and in spec. Hammer to hammer pin fit was good as was housing to pin fit and exhibited no slop, or undue movement in the hammer when
installed.

The safety engaged the first twenty or thirty times a little rough, but don't they all ? I tear them apart and clean first thing, and reassemble
dry on purpose, and left the metal to find each other. The I tear down again after checking all functions many times, and clean and grease.
The safety then worked flawlessly but firm.
I checked the safety to housing wall fit, and the index pin bearing areas. The safety was relieved properly
around the terminal pin just like the G.I. ones. There was no drag on the housing wall like I have seen in several G.I. safeties.
I specifically looked here to make certain the extra top of the print thickness of the 762MM safety would not be an issue in this area.
The extra thick bottom where it passes thru the rectangular housing window, did cause a tiny scratching of the safety above the lock hole
during functioning. It then seemed to subside once the park was knocked off. A little cold blue, later confirmed this. I also went ahead and
polished the inside of the pass thru window sides and reblued.The safety spring housing teet that keeps the safety spring from creeping away from the inside wall was missing, and appears to have been a slight oversight during manufacturing. Once they corrected the previous burr problems at this location,
I suspect the machine was neglected from being reprogrammed to leave the stopper teet in for the safety spring.
I have made Chris aware of this and it is being fixed I'm sure. The spring cannot go anywhere once the safety is installed anyway, so I believe it was incorporated in the design for assembly purposes only,...just my opinion.



Trigger comparisons: As seen above in the photographs, a novice would be hard pressed to find the differences, I couldn't.
The only thing I did find was the pin that holds the sear to trigger assembly looks different on the ends, thats it.The G.I. has a slight concave
on both ends, and the 762MM is smooth. The play from side to side of the sear, and fore and aft movement, was the same in all checked.


Springs and pins, hammer spring housing, and plunger all appeared the same as G.I. comparitors. Measurements confirmed this as well.
I always polish my plunger tip where it contacts the hammer, and polish the hammer at same location, there was no exception made here.
I find all trigger groups to be lacking in this area, including G.I. The one I received was fine but I always suggest a light greasing here.
The thing I noticed most, was that it did have grease at this location upon arriving. Looks like someone else knows my tricks.

I was a little concerned about the installation in my rifles after noticing how thick the trigger group spline was, and their habit of going big on everything.
I had to wiggle it pretty good to get it in an SAI, but it fit without changing or working on it any, then upon removal, it showed slight chafing at the very top of the park.
Once again, a bit of grease and a few more insertions solved this. I took it out with two rounds for it's maiden voyage, for safety reasons. No problems were noticed, so
I loaded four, again no problems. The next shots were with ten rounds and all ignited and fired without incident. Action cocking of this unit worked as it should and I had no
failures of any kind. I went ahead and got off 36 rounds total before the rain moved in and I got sleepy...heh heh heh...

In closing, I would say these guys are about to get most of the little money I have left, but you can't take it with you anyway.
I can't think of anything better to spend it on than this right now, or I would be. I also called Chris and ask him to send me a collection of his manufactured
small parts and a bolt to look at, and have volunteered to check them out for him by using in an upcoming build, and do evaluations on. He has agreed, so keep watching for future
updates. I think it is important at this time to state that I am receiving nothing in return for volunteering my services and have also told Chris that I would return products sent to me
upon request. Maybe he won't haa haa !!

All disclaimers apply, this review is for the trigger group I received, and as usual, I recommend all users check with a qualified armorer or gunsmith
if they have any concerns about any products, from anyone, for the M14 rifle platform.

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Old January 25th, 2011, 11:03 AM   #2
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Ripsaw, thank you for such a complete, well written review. The effort is very much appreciated.

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Old January 25th, 2011, 11:13 AM   #3
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Nice write up. Thanks for your continued contributions!

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Old January 25th, 2011, 11:15 AM   #4
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Thank you for the review ripsaw, and a thanks to Jon as well for pointing out the initial difficulties. I very well might be purchasing one of these for the eventual LRB build, it is nice to know there is a quality new manufactured option to replace the depleting GI part stocks.

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Old January 25th, 2011, 11:34 AM   #5
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Thanks for taking all that time to do that review and sharing it with us Ripsaw!

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Old January 25th, 2011, 12:07 PM   #6
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Excellent review. Thank you for all your efforts on behalf of this community. We will all benefit from your work over time.

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Old January 25th, 2011, 06:43 PM   #7
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Great review Ripsaw!

Being new to the M1A/M14 community I already realize what a HUGE undertaking this new company has taken on. Reviews like this give me the confidence I need to be able to buy with confidence!

Keep on keeping on 762MM!

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Old January 25th, 2011, 07:10 PM   #8
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Pics

Thanks guys. I was looking again at the striations and tool marks on the hammers up against G.I. ones, and these things are definately cool.
First one is safety engaged view, and second is a 3/4 view of the housing and hammer markings....kewl Diamond.
Attached Images
File Type: jpg Copy (3) of 762TG 029.jpg (49.6 KB, 27 views)
File Type: jpg Copy (2) of 762TG 037.jpg (50.8 KB, 38 views)

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Old January 25th, 2011, 07:33 PM   #9
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Excellent review bud! Now to get a decent job so I can afford to buy good stuff....

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Old January 25th, 2011, 07:37 PM   #10
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Thanks Ripsaw for your review of this companies' product. I think 7.62 has listened and improved their product based upon feed back from us in the M14 community. Keep up the good work!

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Old January 25th, 2011, 07:40 PM   #11
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Thanks Rip, that write up took a good deal of time. I'm really glad to hear that 7.62 is really coming along as a manufacturer.

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Old January 25th, 2011, 08:36 PM   #12
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Cool

Thanks ripsaw, very interesting. The whole thing looks like high quality.

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Old January 27th, 2011, 12:56 PM   #13
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Outstanding write up here brother. The time that you have put into this is very much appreciated, and I will be looking forward to your evaluations of other 762MM produced parts in the future.

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Old January 27th, 2011, 05:28 PM   #14
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Super review Thanks Ripsaw for takeing the time to do this.....
This company is something to reckon with the way they are goin an its always nice to have options without haveing to worry bout quality

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Old January 27th, 2011, 10:22 PM   #15
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As everyone else has said before me, Thanks for a great job on your review. I had read JW's review, and it's great to see that 7.62MM is stepping up to address any issues with their products. That's good for them as a company, and even better for those of us looking for parts .........
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