Inline FabricationTitan ReloadingMidSouth Shooters SupplyLee Precision
Graf & SonsADvertise hereStainLess Steel MediaRotoMetals2

Results 1 to 20 of 20

Thread: Options for using PC boolits in tight throated M&P 9?

  1. #1
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73

    Options for using PC boolits in tight throated M&P 9?

    Hello All,

    I've read a lot of posts dealing with PC boolits and/or barrels with tight throats, but I'm not finding a definitive answer to my questions, so I thought I'd ask here.

    First, the background info:

    I have an M&P M2.0 9mm Full Size which has become my favorite gun. The barrel slugs at .3565.

    I have been powder coating for about a year now, using the shake & bake method with powder I got from Smoke. I'm getting fantastic coverage, and I have no complaints about the PC per se. I have several 9mm molds, but my favorite all around is this 35-125Y from Accurate Molds:

    http://www.accuratemolds.com/bullet_...=35-125Y-D.png

    As I said above, the barrel slugs at .3565. I have been sizing to .3569, which is as big as I can go and still get the boolit to slip inside the throat and out to the rifling. I have been loading to 1.075 OAL, which I determined by finding the point where the nose touched the rifling and then backing off .010.

    I have also pulled the boolits to check for swaging, and there is none. I use NOE expanders, which allow me much more control in this area.

    So, the problem is that I've been getting some leading. Not horrible, surface-of-the-moon leading, but definitely some build-up in the angles where the lands and grooves meet. According to everything I've read, I know that I should be sizing my boolits bigger, but if I do that then I would have to load them MUCH shorter because they would hit the tight throat.

    I have made up some dummy rounds with boolits sized to .358, and the max OAL I can have is 1.010. I'm not absolutely against doing this, but beyond the fact that it messes with my ability to use published load data, I'm not sure what other effects it might have. Specifically:

    1) Will the PC get shaved off when the .358 dia. boolit hits the .357 dia. throat?

    2) Will accuracy be affected?

    As far as solutions to this problem (if it really is a problem), I can think of two:

    1) I could have the throat reamed to accept the .358 boolits, although I have learned that M&P barrels are so hard that a special carbide reamer is required, and many (if not most) gunsmiths do not have such a reamer. I have already discussed this option with DougGuy, but his carbide reamer is shot and he's having a hard time getting another one made.

    2) I could buy a different mold that would produce a boolit with a nose profile that would slip inside the throat. Here is one such mold: http://noebulletmolds.com/NV/product...tqi64r3s2n5l95
    This might be an improvement, but Question #1 still stands: will the PC get shaved off when the .358 part of the boolit hits the throat?

    I'll leave it there for now. I hope I have provided all the pertinent information, but please let me know if I have omitted something.

    Thanks!

    John

  2. #2
    Boolit Master

    farmerjim's Avatar
    Join Date
    Nov 2012
    Location
    St. Francisville, Louisiana
    Posts
    1,272
    I have a M&P 9. The throat was .355. It would not take my .357 PCed cast. Luckily DougGuy was able to open up the throat on mine. No leading, and it shoots great.
    The PC should not be shaved off if the throat does not have a sharp edge. If it does, you could probably Polish it down with diamond abrasive.
    There is no difference between communism and socialism, except in the means of achieving the same ultimate end: communism proposes to enslave men by force, socialismóby vote. It is merely the difference between murder and suicide. Ayn Rand

  3. #3
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    Thanks for the reply! Glad to hear that throating the barrel worked for you. That's the option that I'm leaning toward, assuming I can find someone to do it.

  4. #4
    Boolit Man
    Join Date
    Mar 2008
    Posts
    124
    Yeah, barrel throating would be the simplest and best option. Bummer that Doug is having a hard time getting a carbide reamer made. I have a Glock barrel that I'd like to send to him to get throated, but they're just as hard as the M&P barrels. Maybe someone with more experience with this could correct me, but would nose sizing work here? Squeeze it down enough that it'll slip past the throat, but keep the driving bands sized to .357 or .358?

  5. #5
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    I think that would work, and you can buy molds that produce bullets like that, such as:

    http://www.accuratemolds.com/bullet_...=35-125B-D.png

    or the one I mentioned in the OP. That might be the best way to go.

  6. #6
    Boolit Master
    Join Date
    May 2017
    Location
    Round Rock, TX
    Posts
    152
    It sounds like you are already having problems with the coating shaving off when entering the throat or from an overly sharp transition from the chamber mouth. You could try a poor man's throating job by fire lapping. I had a Springfield XD 9mm that leaded with everything, including sizing to .358" with PC and confirmed no boolit swaging. Bear in mind this wasn't a finely tuned match pistol... I fixed it by running a patch wrapped over a bore brush and smeared with JB Bore Paste through the throat and chamber probably 150 strokes. I had the barrel in a padded vice and it was too hot to touch when I was done. Just a thought.

  7. #7
    Boolit Master






    Lloyd Smale's Avatar
    Join Date
    Mar 2005
    Location
    munising Michigan
    Posts
    13,746
    does dougguy have a web site or does someone have contact info. Ive got a 9mm m&p that could stand to be throated a bit too.
    Soldier of God, sixgun junky, Retired electrical lineman. My office was a 100 feet in the air, closer to God the better

  8. #8
    Boolit Man
    Join Date
    Mar 2008
    Posts
    124
    I've always just PMd him through the site, here. He usually responds pretty quickly

  9. #9
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    Quote Originally Posted by KVO View Post
    It sounds like you are already having problems with the coating shaving off when entering the throat or from an overly sharp transition from the chamber mouth. You could try a poor man's throating job by fire lapping. I had a Springfield XD 9mm that leaded with everything, including sizing to .358" with PC and confirmed no boolit swaging. Bear in mind this wasn't a finely tuned match pistol... I fixed it by running a patch wrapped over a bore brush and smeared with JB Bore Paste through the throat and chamber probably 150 strokes. I had the barrel in a padded vice and it was too hot to touch when I was done. Just a thought.
    I'm not sure about that.... I've used a PC bullet to slug the barrel, and the PC stayed intact. Not that that's the same as firing a bullet, but it gives me some confidence. I'm going to the range today, and I'm going to fire a few rounds into the berm and dig out the bullets. That should tell me what I need to know.

    I'm pretty sure the leading has been caused by shooting bullets that are too close to bore size instead of going larger. I thought I could get away with it because of the PC, but I guess not. I didn't notice it at first, because the leading is really not that bad, but it's definitely happening.

    I've found a mold at Accurate Molds that I am thinking of having Tom modify. This would be a TC bullet with a reduced diameter at the front of the drive band, which would slip inside the throat, thereby a) allowing for a longer OAL, and b) helping to locate the bullet for a possible increase in accuracy. If I go through with it, I'll post a link to the new design. I can't believe no one has come up with this exact design before, which makes me nervous since I am not a genius.

    Thanks,

    John

  10. #10
    Boolit Bub
    Join Date
    Jun 2018
    Posts
    27
    I went out and shot some Lee 124 grain LRN bullets that I powder coated twice with Eastwood powder through my M&P 2.0 Compact. They shot just fine and the barrel is clean. I had them loaded to an OAL of 1.065.

  11. #11
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    Quote Originally Posted by ThomR View Post
    I went out and shot some Lee 124 grain LRN bullets that I powder coated twice with Eastwood powder through my M&P 2.0 Compact. They shot just fine and the barrel is clean. I had them loaded to an OAL of 1.065.
    What was the diameter of the bullets compared to your bore?

    Thanks,

    John

  12. #12
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    Here is a link to the bullet that I "designed" (by having Tom at Accurate Molds modify an existing design):

    http://www.accuratemolds.com/bullet_...=35-126M-D.png

    This way I've got a basic TC bullet, but with a .350 diameter portion ahead of the case mouth that will easily slip inside the throat (growing to approximately .352 after powder coating). The .357 portion will be sized to .358 after powder coating, and the rest will extend .340 beyond the case mouth. That's the plan, at least; if anyone sees anything wrong with this idea, please let me know!

    Thanks,

    John

  13. #13
    Boolit Bub
    Join Date
    Jun 2018
    Posts
    27
    Quote Originally Posted by jmac2112 View Post
    What was the diameter of the bullets compared to your bore?

    Thanks,

    John
    Bullets were sized to .356. I have no idea what the barrel slugs at.

  14. #14
    Boolit Man
    Join Date
    Mar 2008
    Posts
    124
    Quote Originally Posted by jmac2112 View Post
    Here is a link to the bullet that I "designed" (by having Tom at Accurate Molds modify an existing design):

    http://www.accuratemolds.com/bullet_...=35-126M-D.png

    This way I've got a basic TC bullet, but with a .350 diameter portion ahead of the case mouth that will easily slip inside the throat (growing to approximately .352 after powder coating). The .357 portion will be sized to .358 after powder coating, and the rest will extend .340 beyond the case mouth. That's the plan, at least; if anyone sees anything wrong with this idea, please let me know!

    Thanks,

    John
    That looks like a nice design. I think you should have some good luck with it

  15. #15
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    Quote Originally Posted by asmith80 View Post
    That looks like a nice design. I think you should have some good luck with it
    Thanks for the input! My only concern is that I've always heard that when the round is chambered, the bullet should be almost touching the rifling for best accuracy. This design solves my OAL problem (or more to point, my seating depth problem), but I estimate that the bullet will travel about .070 before contacting the rifling. One way to correct this is to increase the diameter of the portion that will be in the throat, and I will probably end up doing that. I just don't want to overdo it and end up with bullets that won't chamber. The powder coating consistently adds about .002, so I'll have to take that into account.

  16. #16
    Vendor Sponsor

    Smoke4320's Avatar
    Join Date
    Apr 2013
    Location
    Right here ..at least I was a minute ago
    Posts
    3,687
    jmac2112 Looks like an interesting concept .. Please keep us apprised of the end results ..
    I carry a Nuke50 because cleaning up the mess is Silly !!

    http://www.bing.com/search?q=nuke50&...7ADE&FORM=QBLH

    Selling Hi Quality Powdercoating Powder

    PULSAR night vision and thermal dealer !!!
    PM me for a good deal

    I am not crazy my mom had me tested

    Theres a fine line between genius and crazy .. I'm that line
    and depending on the day I might just step over that line !!!

  17. #17
    Boolit Master




    badgeredd's Avatar
    Join Date
    Feb 2008
    Location
    there, not here
    Posts
    2,288
    Quote Originally Posted by jmac2112 View Post
    Thanks for the input! My only concern is that I've always heard that when the round is chambered, the bullet should be almost touching the rifling for best accuracy. This design solves my OAL problem (or more to point, my seating depth problem), but I estimate that the bullet will travel about .070 before contacting the rifling. One way to correct this is to increase the diameter of the portion that will be in the throat, and I will probably end up doing that. I just don't want to overdo it and end up with bullets that won't chamber. The powder coating consistently adds about .002, so I'll have to take that into account.
    Although generally this is true, I have several firearms (semi-auto pistols,single shot pistols [Contenders] and rifles) where it isn't necessary. Try both and see if there is a REAL difference. Good luck with your experimenting.

    Edd
    Charter member Michigan liars club!

    "The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in Government." -- Thomas Jefferson

    "Consider the clown(s) just one of God's little nettles in the woods, don't let it detract from the beauty. Sooner or latter you are going to run into the nettles regardless of how careful you are."

    Beware of man who types much, but says nothing.

  18. #18
    Vendor Sponsor

    Smoke4320's Avatar
    Join Date
    Apr 2013
    Location
    Right here ..at least I was a minute ago
    Posts
    3,687
    Jmac2112 .. I shoot mostly rifles .. many moons ago I was a 1000 yd competitor.. accuracy is a absolute must in that game
    so when I started shooting cast many of the same loading methods were employed in my testing.. to get to the point
    on a starting testing load a bullet would be seated in a slightly loose neck. rd chambered, ejected and then measured. whatever that length was I would set my seating die 10 thousands shorter. thus giving my loaded rds a 10 thousands gap to the rifling .. this practice is continued to this day for ALL my rds and I can assure you it has never caused me an accuracy issue.. Now I do only shoot powder coated rds .. never tested this with lubed rds
    I carry a Nuke50 because cleaning up the mess is Silly !!

    http://www.bing.com/search?q=nuke50&...7ADE&FORM=QBLH

    Selling Hi Quality Powdercoating Powder

    PULSAR night vision and thermal dealer !!!
    PM me for a good deal

    I am not crazy my mom had me tested

    Theres a fine line between genius and crazy .. I'm that line
    and depending on the day I might just step over that line !!!

  19. #19
    Boolit Man
    Join Date
    Mar 2008
    Posts
    124
    I used that same method to get the best OAL in my 9mm pistols. Works well

  20. #20
    Boolit Buddy
    Join Date
    Apr 2017
    Posts
    73
    Quote Originally Posted by Smoke4320 View Post
    Jmac2112 .. I shoot mostly rifles .. many moons ago I was a 1000 yd competitor.. accuracy is a absolute must in that game
    so when I started shooting cast many of the same loading methods were employed in my testing.. to get to the point
    on a starting testing load a bullet would be seated in a slightly loose neck. rd chambered, ejected and then measured. whatever that length was I would set my seating die 10 thousands shorter. thus giving my loaded rds a 10 thousands gap to the rifling .. this practice is continued to this day for ALL my rds and I can assure you it has never caused me an accuracy issue.. Now I do only shoot powder coated rds .. never tested this with lubed rds
    I have usually gone with about .010 also, which is my idea of "almost touching the rifling." I'm not sure what the result would be of having a .070 gap, though.

    On the other hand, with my proposed bullet there would be only a slight gap before the .358 portion enters the throat, and I suppose the straightness of the bullet in the bore would depend on how straight it is when it enters the throat. But I'm probably obsessing about nothing, especially since I'm not shooting bullseye at 50 yards.

    I love the powder I bought from you, by the way!

    Thanks,

    John

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check