M&P45 range report with trigger job


September 18, 2010, 01:16 PM
I bought my 4.5" M&P45 last month with the anticipation that I would try a trigger job myself based on M&P trigger job PDF posted on Dan Burell's website (http://www.burwellguns.com/M&Ptriggerjob1.htm). He has disclaimers, "As a note I did not write these directions they were emailed to me anonymously, after being contacted on a forum. So we all owe him or her a big thank you!" Also, "Modifying a gun as described voids the warranty. If you shoot yourself, someone else, or anything as a result or perceived result of modifying your gun as described you are responsible." So, make these modifications at your own risk. As always, please consult a qualified gunsmith if you are not comfortable/competent to modify any part of your firearm. Be safe.

S&W website (http://www.smith-wesson.com/webapp/wcs/stores/servlet/Product4_750001_750051_765773_-1_757782_757781_757781_ProductDisplayErrorView_Y) indicates M&P45 trigger pull at 7 lbs. When I compared the trigger pull to my well seasoned Glock 22 trigger, it definitely took more effort to release the striker and the trigger felt "gritty" during the trigger travel. Even with the heavier/gritty trigger pull, the front sight did not move when I dry fired the pistol.

Initial Cleaning:
After field stripping the pistol for the initial cleaning and checking the PDF, the source of "gritty" trigger travel seemed to come from some roughness noted on the trigger bar contact surface as it slid under the sear.
http://www.thehighroad.org/attachment.php?attachmentid=127820&stc=1&d=1284824570 http://www.thehighroad.org/attachment.php?attachmentid=127821&stc=1&d=1284824570

The barrel was measured at 0.451" at the grooves and 0.442" at the lands. My 200/230 gr lead reloads taper crimped at 0.472" dropped into the chamber freely with a "clink".

To establish baseline shot groups from the stock trigger, I did not polish any of the trigger parts. After the pistol was cleaned with Hoppes #9 and lubed with BreakFree, it was reassembled.

Range Session 1:
M&P45 barrel rifling comes coated, but not polished. At the range, I shot 200 rounds of factory FMJ (Winchester/PMC) through the barrel to "burnish" the barrel rifling (I am not sure if this is necessary anymore, but it's been my practice for years - except for Glock barrels) before shooting my reference loads (200 gr SWC and 230 gr RN Missouri Bullets with 5.0 gr of W231/HP38 - my Pro Auto Disk drops 4.9 gr).

Initial 5 yard shot groups were shooting a little to the right of POA, so the rear sight was drifted to shoot POA. 7 yard shot groups off hand averaged 1.5" and 10 yard shot groups averaged 2"-3", which is bigger than what I expected at these distances. 200 rounds of reference loads were shot.

Second Cleaning and Trigger Job Session 1:
After field stripping the pistol, barrel chamber/rifling was checked for leading. There was no sign of any leading. A few strokes with copper bore brush dipped in Hoppes #9 cleaned the barrel.

Following the PDF, I disassembled the sear housing. Since my M&P45 came with ambi-safety, it required the additional step of removing the safety (it simply slides backwards from the sear housing). =WARNING= Be careful of the small spring (1/16"x1/2") that pushes on the safety block as it popped out and I had to look for it (after 20 minutes, I found it). :mad:

Note: Since this was my "rough" run, I only did about 50% of what the PDF indicated on the filing of trigger parts. I made sure to file out the roughness on the trigger bar. I lightly filed the striker, but did not alter the firing pin block. I also did not polish my filed surfaces as I anticipate further filing/polishing after my range session.

Pistol was then cleaned, reassembled and lubed. I was very happy to feel that the gritty trigger travel was gone! :D Trigger pull was now smooth with more crisp striker release. However, heaviness of the trigger pull was about the same.

Range Session 2:
Since I was low on my supply of 200 gr SWC, I loaded up some 200 gr RN (IDP #4-XD) from Missouri Bullets at 1.20" OAL with 5.0 gr (4.9 gr actual) of W231/HP38.

7-10 yard shot groups off hand averaged sub 1"-1.5" and 15 yard shot groups averaged 1"-2". I then put the targets (half sheets of copy paper) at 20 yards and got 1.5"-2" average shot groups with the best 3 shot group of 1.25" pictured below.

I think this trigger job PDF certainly holds great promise as my 50% filing job surfaces are not even polished yet. I plan on doing more range tests before I file any more trigger parts as I am quite happy with the current results.

A BIG thanks to Dan Burell (http://www.burwellguns.com/index.htm) for sharing this information with M&P owners!

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September 22, 2010, 11:22 AM
Excellent. Rounding off the striker block will really help as will a final polish. The striker engagement surface can be a bit tricky, I over did one just to see where that point was (the trigger pull was below 1 lb. at that point).

Sounds like you've got a sound approach to the work being done.

October 2, 2010, 06:18 AM
Third Cleaning and Trigger Job Session 2:
After field stripping the pistol, barrel chamber/rifling was checked for leading. Still no sign of any leading. A few strokes with copper bore brush dipped in Hoppes #9 cleaned the barrel.

Using my wife's nail files/polish sticks, I removed all the rough file scratches left on the surfaces from Trigger Job Session 1.

Please note that I took care to leave the striker surface flat with the factory sharp edge intact - no cutting or rounding was done, just surface polishing. Talking to several other match shooters who also do their own gunsmith work confirmed that striker surface should be left flat and polished only. No cutting or rounding of the striker edge should be done.

As to the sear, the part that contacts the trigger bar was cut 50% of the finished sear in the PDF, but the angle was matched and polished. The back part of the sear that rides the striker was filed to remove the sharp point, but once again, I only did 50% of the job shown in the PDF.

Trigger bar surfaces that contact the sear and firing pin block were polished only. I did remove the rough finish on the trigger bar that contacts the sear initially with the file, but to make the surface flat for polishing.

Nothing was done to the firing pin block.

Pistol was reassembled and lubed. Trigger pull was now more smooth with lighter release of the trigger than before. I would say the factory 7 lb trigger pull was now more like 5 lbs.

Range Session 3:
Since my restock order for 200 gr SWC from MBC arrived (I tell you, they are consistently quick with their shipping), I decided to do range session #3 with them. I loaded them with 5.0 gr (4.9 actual from my Pro Auto Disk) of W231/HP38 at 1.25" OAL.

Since the trigger job parts were polished, I wanted to focus on the accuracy of shot groups at shorter 7-10 yards to reduce shooter induced flyers.

7 yard shot groups off hand averaged sub 1" with many clover leaf clusters. 10 yard shot groups averaged 1.5" and were "tighter" than range session #2. Since the trigger pull was much smoother and lighter, I found myself focusing less on not moving the front sight and more on the shot groups.

Why not range test from pistol rest/sand bags?
Some of my shooting buddies asked me why I don't test shot groups with support from sand bags/pistol rest. Well, thanks to a range master who taught SWAT/PD/SD, I have approached my USPSA shooting and range practice with "Practical" point of view. He often emphasized that outcome of immediate threat gun fight will be decided within a second of time frame. During this fight/fight vs fight/flight brief moment, your one hand/two hand grip will be the only thing that will support your pistol - no sand bag or pistol rest will come into play. It is for this reason why I range test off hand and use match speed double taps (two aimed shots fired within a second) for my evaluation of pistols/loads.

October 2, 2010, 08:18 AM

Great report. Here's a tip: Glock striker springs fit the M&P perfectly, allowing you to reduce the pull weight a noticeable amount. The stock M&P striker is much stiffer than a stock brand G. I installed a stock G striker spring in my M&P45 and never had a mis-fire and enjoyed a lighter pull.

I also did the Burwell thing on my M&P and it turned out very good. It was actually quite amazing for a striker gun. Unfortunately, I sold mine, which I regret.

October 2, 2010, 09:52 AM
schmeky, thanks for the tip!

October 2, 2010, 11:08 AM
Fourth Cleaning:
After field stripping the pistol, barrel chamber/rifling was checked for leading. There was very slight leading along with some fouling buildup near the chamber end. Since range sessions 1&2 were done with 200 gr RN loaded to 1.20" OAL and without any leading, I suspect that I may need to increase the powder charge for the 200 gr SWC rounds loaded at longer 1.25" OAL to provide better obturation of bullet base.

Since the M&P45 barrel is coated stainless, I soaked the barrel in WD40 for 15 minutes and softened lead deposit was removed with copper scrubber wrapped bore rod. Note: I only use WD40 on the inside of the barrel and follow with swabbing of Hoppes #9.

Pistol was reassembled with all trigger contact surfaces lightly lubed with BreakFree.

Range Session 4:
After range session #3, the trigger pull lightened even more and became smoother. It now feels comparable, and perhaps even lighter than my new G27 trigger and as light as my well seasoned G22.

7 yard shot groups off hand averaged tight sub 1" groups with many double shots through the same hole out of 3-5 shot groups. 10 yard shot groups averaged sub 1.5" groups and I feel the pistol is shooting more accurate than my hands (I may do some supported shooting from sand bags at 15-25 yards at future range sessions).

I did some double-tap drills at 7-10 yards and they were consistently 1.5"-3"/2"-4" apart and mostly vertical. Front sight flash shots at 15-20 yards placed all of my shots in the 1/2 sheet of copy paper. My initial off hand 15 yard shot groups are averaging 2"-2.5".

Thinking about repeating the range session #4 tests using the 200 gr RN and/or 200 SWC with increased powder charge (like 5.2 gr). With my results so far, I think S&W has a very viable match shooting 45ACP pistol for IDPA (SSP, ESP, CDP) and USPSA Limited-10 classes.

Update: BTW, the M&P45 is now back to shooting a little to the left of POA. I guess, had I not adjusted the rear sight, it might be shooting POA by now. Will be drifting the rear sight back to center on the next range trip.

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