BACKGROUND INFO
Before we get started, I would like to take a moment and bring you up to date with this small project. I purchased a Bushmaster ACR enhanced model rifle chambered in 5.56mm with a 16 inch barrel. As with most 'out of the box' rifles, the trigger needed some help. However, I have read that some of the trigger sets would not work because of the fact that the ACR trigger set ( which uses AR trigger parts ) installs in a trigger package that is open on the top and bottom. This means that the commonly used set screws would not be able to work off of the bottom of the ( normal AR ) lower receiver. Also mentioned was the fact that the ACR hammer spring was different, and that it would need to be reused. Bummer!
I took my rifle apart and thought that I would take a look. While the actual trigger package is open on the top and the bottom, the trigger package does install into the ACR's lower receiver and bottoms out on the inside lower frame. So, there is a bottom, as such, and the set screws can reach it. I really love JP Enterprises trigger sets. I have them in most of my rifles, and I have used them for many years. So, I decided that I would order up a new trigger set and give it a go. I really would like to install the JPFC-1 trigger set in my ACR.
I got to JPRifles website and I noticed that the JPFC-1 (original trigger set) was now at a lower price. All right then, what could be better than what you want at a better price. Well, then I saw it. I saw the new JPFCP-1EZ trigger kit. A new trigger kit! Well I don't have one of these. And the thing only has one (1) set screw that might need to touch the bottom. Notice here that I said 'might need' to touch the bottom. I will bring this up a little later in this project report. The picture below is what I purchased from JP Enterprises. It comes complete with all needed parts including new anti-walk pins, several different springs and a new safety selector. It also comes with all of the Allen-keys and Loctite that is required. One sould expect this attention to detail and quality from the JP Enterprises. JP Enterprises aslo sends along a very good manual and a DVD instruction tutorial. JP Enterprises delivers a very first rate product. If you haven't looked into their products, check them out.
If you are reading this post to learn and understand the topic, please read through this entire post to see if there are things that you don't understand or things that you are not willing to do. This project of mine is something that a lot of folks just won't do. And that's OK. This post is simply just for me to provide information that others might find interesting. Let me state here that this post is only intended to document a project of mine and NOT to provide a How-To in the art of installing trigger sets. So please read all of the post before you do anything and learn all you can. Then one day you might like to do your own project.
MY PROJECT
1. First off and very very important is that anytime we handle firearms we must check and then recheck it again to make sure that the firearm is unloaded, magazine is out of the gun and there is NO ammo anywhere in the same room. We all know this drill and I live my it.
2. I would normally assume that if you are going to install a trigger set in your rifle that you know how to remove the lower receiver. The ACR being a new rifle and for those that would like to follow along, only for learning how to break down this rifle, I will present a quick lesson on how to separate the lower receiver on an ACR rifle. First, push the top pin on the lower receiver next to the stock to unhinge the upper. Remove the bolt and set it aside. Push the front hinge pin and remove the rest of the upper receiver. ( basically, just like an AR so far.) Push the lower pin on the lower receiver next to the stock and remove the stock. Yes, it will come up and out! Now you should have the lower receiver with the original trigger pack still installed. It should look like the picture below.
3. To begin the process of removing the trigger pack, I will need to remove the safety selector. To start this process I pushed the hammer down into the cocked position. Then I pulled up on the small lever that is just above the safety selector on the other side of the receiver (shown in second picture ). While I was pulling up on the small lever, I rotated the safety selector to the 6 o'clock or down position as shown below. ( YES! The hammer needs to be cocked for the switch to move correctly. )
This photo shows the safety selector rotated to the 6 o'clock position.
4. Now, I flipped the lower receiver to the other side. On this side of the receiver, the safety selector switch knob needs to come out. That's right, it pulls out. I was surprised to find out how hard this part is to get out. Then I remembered that I needed to lift the small lever again. It is still hard as hell, but it did come straight out. Some folks can use their finger tips and nails to the job. I can't. But, I did use a small pocket knife blade and worked it up under the knob. Do not go prying on it with anything massive!
See, I told you it came out! And look at that, not a mark on my rifle.
5. Flipping the receiver back to the left-hand side. I pulled up once again on the small lever and pulled the safety selector out of the lower receiver. This required almost no effort, it came right out.
6. Finally, I can remove the original trigger pack. By pushing up on the trigger and grabbing the trigger package from the top, I removed the trigger package with little to no effort.
It comes out looking just like the photo shown below. Yes, I know that this is a picture with the JP-1EZ trigger set installed. You can tell by the speed hammer. I forgot to take a picture of the original trigger package as I took it out. But, you get the picture, right?
At this point, take notice of the trigger pack. You should see the hammer and the trigger pins. You should also see a small roll pin below the hammer pin. This roll pin DOES NOT COME OUT during this project. Please leave it alone.
7. Before I take the hammer and trigger out, I need to talk about the hammer spring for a moment. Shown below are ( left to right ) the original hammer spring, JP Enterprises red spring and the yellow spring. I mentioned at the beginning of this post that I had read where I was going to have to reuse the original hammer spring because it was different. Well guess what? It is! The right side of the hammer spring (looking from the disconnector forward) has a small bend in it. This bend is bent towards the center. This allows that little small lever that I pulled up on earlier (to remove the safety selector) to have a little spring pressure. That little bend fits into a groove in that lever arm. I simply took my new springs and I put a small matching size bend in both of them. Easy to do. The spring wire is not that hard to bend. I was very careful here, I did not want to bend and re-bend these springs. I moved the wire in the correct direction a little at a time until I got the desired bend.
Take a look at this picture below. What is important to see here is that the hammer spring is shown going into the safety selector retaining piece. If you push up on it from the bottom here with a small punch or flat blade screw driver and pull up on the small lever from the top side, the spring will come out of the small lever piece so it can be remove. Follow along with my progress through this operation in the next several pictures
8. I pushed up on the spring as shown above while pulling up ( or out ) on the small lever. This operation is not shown. As soon as I had push the spring and lever far enough in the up position, the spring came out of the groove in the lever and it came right out of the trigger package.
This photo shows the lever un-sprung and removed from the frame.
Note: As long as you push up on the spring far enough, the piece that holds the safety selector in place will come off the spring and into your hand. Then slowly lower the spring. In the photo below is seen a close-up of the small lever. The small triangle tip you see in the top center of the large hole is what fits into a groove on the safety selector and that is how the safety selector switch stays in place. This is not the best picture I have taken, but it shows the side of the lever that works against the side of the trigger package itself. It does show the slot that the slightly bend spring rides in and it is held there by the fact that this piece rides against the inside wall of the trigger package frame.
9. At this point, I went ahead and removed all of the other trigger parts from the trigger package. No! your eyes aren't deceiving you. The parts shown in the photo are the JPFCP-1EZ parts and the hammer has the red spring installed on it. I was hoping you wouldn't catch that. However, the original parts are only a little bit different.
Here is a close-up look at that roll pin that I mentioned earlier. This pin is what the trigger spring works off of instead the bottom of the receiver. I did not remove it? You should not either!
10. I picked up the new JPFCP-1EZ trigger and installed the trigger spring as shown. Also, at this time I installed the over-travel set screw ( without Loctite ). I verified that the disconnector spring was installed.
One item that I need to mention at this time is the area to the right of the disconnector spring. That part of the trigger piece fits up under the safety selector drum. This is the safety engagement pad or the safety engagement area. Later when I am talking about that topic, please refer back to this picture, if needed, to help with remembering where this area is located.
Below is shown a picture of the new JPFCP-1EZ disconnector. Notice that the disconnector timing is now done with a small set screw on the disconnector itself. It no longer needs to be cut down and hand fitted. It is now set screw adjusted. At this time, I installed the small set screw in the front of the disconnector.
( do not use Loctite yet! )
11. Installing the trigger into the trigger package. NOTE: I installed the standard ACR trigger pin. The pins in my JPFCP-1EZ kit are designed to be oversized. The .156 size pins are just a very little bit oversized for this trigger package's pin holes. Since, I did not want to oversize the holes in my frame just yet, I elected to go ahead and use the original ACR pins. ALSO, I installed the trigger pin with the locking groove on the left-hand side ( while looking from the trigger towards the hammer location ).
When all is said and done, I verified that the trigger spring will rest on the roll pin as shown when the trigger is rotated around into its normal place. ( it will rotate and flop around freely at this point ). So far this trigger set looks very much like it is going to work well in my rifle.
12. I picked up the speed hammer and the yellow hammer spring. Pictured below is the yellow ( 3.0 - 3.5lb ) spring. I installed it on the hammer as shown, and I installed it in the trigger package as you would normally do using the standard hammer pin that came with the ACR. The kit comes with oversized pins that I will install at a later date. At this time, I just used the original pins. The original pins also fit nicely into the hammer and the trigger, but there is just a slight (barely perceivable) side to side movement while using the original pins, but not enough to spoil this project.
After the hammer and spring are installed, it should look mostly like a standard AR trigger arrangement. Notice the yellow hammer spring has that small bend in it that I made earlier. This will work with the safety selector switch retaining lever.
Here is a quick bottom view of the installation to this point. The over-travel adjustment set screw can be seen just to the upper left of the trigger.
13. At this point, I located the small Allen-key that fits the set screws. I adjusted the overtravel screw most of the way up ( away from the bottom ) and then crudely adjusted the disconnector screw. I adjusted the disconnector set screw until the catch on the hammer and the catch on the disconnector did not touch each other. At this time, I only want the sear to hold the hammer back. Now, when I cock the hammer, with the trigger released, the sear will catch the hammer. When I pull the trigger the hammer is released. The disconnector will be set up a little later in the post. Right now the hammer just needs to work off of the trigger and the sear.
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How about a break at this point? I need one! I also need to make a statement about modifying the trigger part that I am going to do. You might ruin the part or make the trigger system un-safe if care is not taken to fit this part correctly. This project is for your information only! I am willing to take the risk, you might not.
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14. Now, I slid the safety selector into the trigger package to see if it will go all the way through to the other side. Mine did not. ( I set mine up with the hammer cocked. ) My safety selector drum was causing the drum to hit the other side just a little bit high. Just high enough so the selector drum would not go into the hole on the other side.
This is where the custom fitting comes into play. It is not a hard thing to do, but it needs to be done correctly. Here's how I did mine.
Remember back a few photos ago, when I mentioned this part of the trigger? ( see picture below ) This part of the trigger fits under the safety selector drum. If your selector drum does not go in correctly you will need to use a file to remove a little metal from across the top of this area. It will require you to take the trigger set out and put it back several times. But, that is the only way to do this correctly. ( or the only way that I know how to do it ).
15. I once again proceeded with taking the trigger out and mounting the safety engagement pad in a small vice. I started removing a little metal with a small file. I have a small 6" metal file and this effort would be different if I had a big 12" file. So, be careful with whatever file you have. Keep it flat and straight. I took off a few thousandths and put the trigger back in and tested the selector fit. It was a little better, but still not right. So, I took it out again. I took off another little bit of metal and reinstalled the trigger again. Almost there. I took the trigger out one more time and took off just a little bit more, not much, just about another 5 or 6 strokes with the file. I reinstalled the trigger and tested the selector switch again. I think I have it about right for now. When I slide the selector drum into place, I can feel it dragging ever so lightly on the trigger safety engagement pad. Better yet, it now fits into the other side as it should. Please be careful here. You need the trigger safety engagement pad to lightly drag or touch the safety selector drum. I don't want the trigger to move much if any at all, when the trigger is pulled. I took the trigger out one last time and hit it with just a couple file strokes and then finished up with a small polishing stone to provide for a smooth finish to the pad area. This is one item that I worry about. The trigger is metal and the saftey is plastic. Once cut to work perfectly, over time the metal trigger may/will wear on the plastic saftey drum and this will allow the saftey switch to let the hammer fall because the of added trigger play and the light sear engagement. This might become the no-go point in this project. Please think about this before proceeding.
NOTE: When fit correctly, the safety selector drum should come straight across and plug into the opposite side as shown below. I now tested the safety selector. I rotated the safety selector to the 9 o'clock position ( safe ). The trigger only moved a slight amount. I then moved the selector to the 12 o'clock position ( fire ). The trigger moved enough to release the sear and drop the hammer. I tested this several times to make sure that this is correctly done.
16. I am now going to remove the safety selector drum and finish the trigger package installation with the installation of the small lever that secures the safety selector switch. I started by pushing the bent leg of the hammer spring up from below with a punch. See picture below.
At this point, I installed the lever's pivot pin in it's hole and move it into place making adjustments to the spring and the lever to allow the spring to enter the groove in the lever. Once spring pressure was released by the punch, the lever moved down into the frame. It will ride against the outside wall keeping the spring contained. I made several attempts to make the catch. If you take your time, it will eventually go back together again.
Once in place, the trigger package has been completed and it is ready to be installed back into the rifle's lower receiver. Here are a couple of photos from the top and the bottom of the trigger package.
( The disconnector timing and overtravel adjustments will be made with the trigger pack installed in lower. )
I put the trigger package back into the lower receiver and installed the safety selector switch. Once the trigger package was reinstalled in the lower receiver I can move on to the disconnector timing. This is how I but it back togerther.
17. With the hammer cocked, I installed the safety selector switch in the left-hand side of the receiver. The selector switch is installed with the hammer cocked and pointing down. The small lever will need to be pulled up a little to let the switch drum go all the way through to the other side.
The opposite side of the receiver should look like the photo below.
18. I then installed the right-hand side of the selector switch. It is pointing down and I pulled the small lever up a little and it snapped right into place. When it did, I lowered the small lever.
19. I must test the safety selector now that it is in the rifle. I rotated the selector switch from the current 6 o'clock position to the 9 o'clock position ( safe ). Your trigger package may move just a little in the lower receiver at this point. It should not move much at all. Mine moved just a tiny bit in the forward and back direction. Holding my hand on top of the hammer and the front part of the trigger package, I tried to pull the trigger. If your safety engagement is correct, there will be NO movement of the trigger ( ok, maybe a small perceived rearward movement, but that's all ). The hammer should NOT be released under no circumstance! Mine was just right.
20. Now, I rotated the selector switch to the 12 o'clock ( fire ) position. Holding the hammer slightly, I pulled the trigger and the hammer fell as expected. I did this several times. If you installed the yellow spring set and you think that is might be too light, now is the time to take it back apart and change the yellow hammer spring to the red one. This will raise the trigger pull somewhere around .5 to at most 1 lb. If you are back here after changing springs or if your good to go then I'll continue with the disconnector timing.
21. Looking down into the trigger package, locate the disconnector set screw. This is the set screw on the front porch of the disconnector itself. NOTE: I am not going to go into any great detail about the disconnector timing adjustment. The JPFCP-1EZ comes with a great DVD that explains this setup operation very very well. The kit also comes with a very good manual that explains these steps very well. I will tell you that you will need to practice this setting several times. You will need to undue the setting and come back to it again several times to get the feel for it. This adjustment also needs to be thread locked with the included Loctite 271 product. Basically, you want to adjust the disconnector set screw so that when you cock the hammer with the trigger being held in the pulled condition, the hammer should be retained by the disconnector. Then as you slowly release the trigger, the disconnector should release the hammer and the hammer should now be caught and held by the sear. When this separation occurs, you should hear a click as the trigger is reset. If this is not done correctly then either the disconnector will not release the hammer ( timing is late ) or when the disconnector does release the hammer the sear does not catch it and it falls ( timing is early ). Please go to JP Enterprises website and watch his videos. Please read the manual.
Once you can repeatedly find the correct spot and adjust to it several time. It is time to back out the set screw and apply a very small drop of Loctite to the treads and screw it back into place. Then make these adjustment one more time until perfect and then let the tread lock set up before moving the trigger set again.
22. After the tread lock has setup ( about 20 mins ), it is time to work with the overtravel adjustment. I did not have very much overtravel. I elected not to use the overtravel screw. I did however, play with adjusting it and after several attempts I was only turning the screw about 1 revolution to go from no effect to no trigger release and I had no rubbing on the hammer. This is after all a military style rifle so I left the set screw out.
If you decide to install this kit you will need to make the adjustment and work the hammer and trigger many times to make sure it doesn't affect the trigger and the hammer fall or drag on the hammer. It would also be a very good idea to put the upper receiver on and bolt back in. Pin the gun together and work the action many times to be really sure it is correctly adjusted. Then take the gun back apart and put the Loctite on the set screw and make the adjustment for the last time. Remember, the thread lock material makes the set screws very hard to take back out. It is almost permanent. After the thread lock is applied, let the rifle rest while it sets up.
Now that I have finished the testing and the thread lock has setup, it is time to put the rifle back together and go to the range.
RANGE REPORT!
I took the rifle to the range and could not wait to fire it with this trigger set. I loaded the rifle, took aim and as the wind blew lightly across the range I pulled the trigger for the first time and WOW! What a wonderful and to me a down right dangerous trigger. You see, I installed the yellow spring. ( 3.0 - 3.5 lb ) Let me tell you that with the weight of this rifle, I needed to be very careful about placing even slight pressure on the trigger. The trigger was sound. With the rifle empty and cocked ( fire mode ) I could not make the rifle slam fire by dropping the rifle on the butt stock or dropping it on the table. But, this must have a trigger pull somewhere around 3lbs or so. This trigger pull is too light for my application of this rifle. Other than that it worked great as a bench trigger. Back to the house I went to install the red hammer spring. ( 3.5 - 4.0 lb ).
Back at the range the following weekend, I really liked the red spring in the rifle. It is still a great glass break trigger pull, but the rifle can be run and gunned with this trigger. What a great trigger set, I love it! I guess I will now go ahead and try the last spring. I guess this is a gray color ( 4.0 - 4.5 lb ) hammer spring.
Back to the range again! This spring is more than likely my best choice for an all round rifle setup. It is really nice. As to be expected, it takes the trigger pull up a small notch again. But, it is still crisp and sharp and definitely makes this rifle a rifle to keep and use for a long time. But, I am going back to the red spring. So, back to the house one more time.
My final thoughts on this project:
Back on the range with the red spring once again. A friend and I shot several hundred rounds through the rifle today and it was just great! No troubles and the trigger is as good or better than the older JP triggers that I have in my other AR rifles. This trigger set worked very well off the bench and scoped shots actually went where they should hit. Running and gunning with the rifle is just superb! I think I made a great choice and have no trouble recommending this JPFCP-1EZ trigger package to anyone that might like to upgrade the trigger in their ACR rifle.
NOTE: I am not a spokesman for JP Enterprises and I have no contact with them at all. I purchased their product over the internet and paid full price.
I hope the time that you have spent reviewing my project will be thought of as time well spent. I have enjoyed it and hope you have too.
Thanks,
NB
