Glock 17 7" KKM barrel for Glock 40

Discussion in 'General Glocking' started by OhMyGlock406, Oct 20, 2019.

  1. OhMyGlock406

    OhMyGlock406

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    Bought a G40 for bear defense here in MT and for deer hunting.
    I put a Zev Pro trigger and a 3.5 Connector in her. LW Tungsten Rod and a 24# spring.
    The other day I sighted the Trijicon SRO to 70 yards with 155 gr XTP from Underwood.

    Smoked the egg sized bulls eye! Shot a group off my shooting sticks that would definitely kill a deer.

    Kinda thinking about ordering a KKM barrel or something else that's an inch longer for deer.

    How much of a difference will this make? The factory barrel with the Zev trigger is already pretty dang accurate!
    With an extra inch will I pick up another few FPS? [​IMG]

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  2. thequintessentialman

    thequintessentialman

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    Balistics by the Inch and balistics 101 websites have some good information regarding that. From what I've read, 10mm benefits nicely from longer barrels.

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  3. vitalibertas

    vitalibertas

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    10mm benefits from longer barrels up to about 16”.
     
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  4. Beendare

    Beendare Stick and String, SME, NRA life member

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    My take; I have a little experience with these 10's. I know of a few buddies modding their 10's as we all use them for bear protection bowhunting. I decided to keep my G20SF stock and glad I did.

    FWIW, sure you will pick up FPS....but what about the important stuff; 100% reliable, Drawing with that long barrel, etc.

    The chamber on the KKM barrels is more supported....ie- tighter. I know of problems with reliability with these....not functioning correctly with some of the hardcast bear rounds. A buddy with a 6" KKM can't get a whole mag to function. He has spent considerable time played with springs and such too. He finally had to take to an armorer to make it function.

    A couple buddies have LW barrels, increased springs, extractor that are reliable with reloaded ammo.

    FWIW, all of these instances of modded 10mm's; guys had to do a lot of tweaking to get them right. Of course its a combination of things; Barrel, Springs, Extractor and the big one AMMO. Hardcast ammo with a wide meplat plays heck with some of the semi autos.

    My take; leave it stock. My G20 functions perfectly with Underwood 200gr hardcast. [The 220 gr Underwood tumbled for some reason]

    I did polish the internals.....the $.25 trigger job...and for sure polish the feed ramp....as the hardcast can bite on a rough ramp. I also put a SS guide rod in there...not sure that mattered all that much to followups.

    Leading the barrel; I know, I know....Glock says no in their stock barrel.

    FYI, I tested. I ran 300 rds of the underwood 200gr hardcast through in one session without cleaning. [big $$ in ammo- ouch] but it functioned perfectly. I checked it every 50 rds and it did show a little dulling/discoloration in the barrel [lead] at about the 200rd mark. After 300, there was some minor lead showing....not chunks or anything but a tiny bit. I could have probably shot another 200 rds without an issue but it seems once that leading starts to take hold...it accelerates.

    After shooting the 300 rds, I shot some FMJ through it for the heck of it and checked it; it seemed to lessen the leading...cleaned it a bit.

    I think if a guy cleans his barrel, Leading is NOT an issue with this ammo as very few guys are going to spend the $$$ shooting lots of hardcast at almost $1 a rd at a time through it. I would recommend 200rds max or so...then clean if using the hardcast. Different ammo could be worse...I dunno.

    Note; Buffalo Bore has some jacketed ammo with wide meplat for these 10mm semi autos that I'm sure is great...but its really expensive.
     
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  5. OhMyGlock406

    OhMyGlock406

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    Yeah I'd only use the KKM for deer. The factory barrel would be for the backcountry. Gun loves the 200 gr Underwoods!

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  6. Mountain10mm

    Mountain10mm

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    I've more than messed with the 10mm Glocks. Beendare's post is accurate. You will increase velocity with an aftermarket barrel. I've personally chronographed 100fps increase with a 1" longer barrel. Never measured, but I'm assuming the velocity gains are due to tighter chambers which produce higher pressures. And the chambers are tighter because feeding reliably can/will become an issue. It's a fine line playing with a stock Glock. I find it fun and frustrating at the same time.
     
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  7. harold63

    harold63 I'm not retired

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    Being clear, here...I've looked at a number of barrel comparisons where AM barrels produced less (granted, not much less) FPS than Glock OEM barrels of the same length with the same ammo. IOW, if you got an AM barrel the same length as an OEM G40 barrel, there's no guarantee it will give more FPS.
     
  8. harold63

    harold63 I'm not retired

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    An inch longer for Dear will make a big difference if it's 6" to 7". For deer, not so much. Don't waste your money trying to get 'will already easily kill' to 'will kill just as easily'.

    You got all them AM parts in your G40 defense gun. Bears like them some chew toys when you pull the trigger and it only goes 'click'. 'Click' and a deer running off won't help the hungry bear cause. YtakingachancewithmodifiedglocksandhungrypissedoffbearsMMV
     
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  9. harold63

    harold63 I'm not retired

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    I am off, today, and just sitting here, I've got to say...if you modify a defense gun you know you may actually have to use on a bear, you may as well just carry a base ball bat. It's too much of a risk. Modify your hunting gun all you want. Your defense gun??? Plenty of Darwin awards still to be won. ;)
     
  10. Mountain10mm

    Mountain10mm

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    On same day, with same 180 grain personal reloaded ammo, my G40 stock barrel gave 1334fps. Switched to KKM semi drop it barrel - same length - and got 1413 fps.
     
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  11. OhMyGlock406

    OhMyGlock406

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    That's why I put several mags of my bear loads through it before taking it into the backcountry... Guess how many failures... Why you buy good parts then test them. Not an issue.

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  12. OhMyGlock406

    OhMyGlock406

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    I mean come on boys, you really think I'd modify a pistol and not varify reliability with my bear loads? Then recheck it and check it again because shooting is fun? Zero issues. Zero, none, the gun runs as flawless as any other Glock I own or have owned.

    So instead of typing, hey man did those mods effect reliability any? Y'all went in a several paragraph tangent insulting my intelligence? Grow up.

    Let's get back on topic.

    How's that KKM barrel for shooting deer. Not bears, deer. I think I even specified that in the original post. Stock for bears, AM for deer.

    Moving forward...

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  13. gatorboy

    gatorboy ( . Y . )

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    It's pretty nice
    I'd have to see that with my own eyes to believe it.
     
  14. Lumber31

    Lumber31

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    Personally I bought the G40 MOS when they first were announced. Put a Vortex Venom red dot on it right away. Also added a Double Diamond #3.5 lb. connector. Got it sighted in dead on at 50 yards with Underwood Xtreme Penetrators @ 1500 fps. From the bench I was able to put two rounds in one hole & third shot made about 1 1/2” group at 50 yards. The gun & ammo combo is clearly more than accurate enough for the job. This is my hunting handgun, for deer & hogs. However, I do not live or typically hunt in Grizzly country. Only blear bears or mountain lions where I live.
    When I’m hiking or carrying a handgun while hunting with a rifle, I carry a completely stock Glock 20SF. Reliability is a must!!
    Now when I’m hiking / hunting in Brown Bear / Grizzly country, my handgun is a .454 Casull 4” barreled double action revolver!!!
    When hunting in Grizzly country, your “hunting” handgun better be capable of taking down a Grizzly ASAP because you will may not have time to get to your “back up” handgun!!!
     
    Last edited: Oct 22, 2019
  15. Beendare

    Beendare Stick and String, SME, NRA life member

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    I just saw the MT thing.....and was kicked out of a spot near Yellowstone last year with a wounded grizz running around while bowhunting. I made the assumption you might need it to be 100% reliable......my bad.

    Heck, for deer......why not put a custom 10" barrel on the thing so you can reach out and touch one?

    ...
     
  16. gjarcher

    gjarcher Captain USN ret.

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    I have a G40 and put a 7" KKM barrel on it for Woods Defense (Black Bear, Lion, etc.) while bowhunting and flyfishing.
    • Accuracy at 50yds and beyond won't be that much better, little or none over the OEM barrel. If there is a measurable accuracy difference it is beyond my shooting ability to determine...and, inside of 20yds for Bear Defense ±2" isn't a big deal. Bullet profile proved more of a factor in accuracy than barrel ... Hornady XTP with a longer bearing surface proved extremely accurate over other JHP tested.
    • You will gain some velocity with the longer barrel, hence more ft-lbs impact energy downrange. Different States have different Big Game regs, most require expanding bullets, which eliminates Xtreme Penetrators, hard cast lead, etc. ... some require a barrel longer than 5" (G20 OEM doesn't cut it), some require 550 ft-lbs energy @ 50 yds (Colorado for instance; light fast bullets with low BC often don't cut it ... need 200gr at about 1200 fps).
    IMHO, the 7" KKM barrel in the G40 is justified for Bear/Dangerous Game Defense based on ft-lbs energy on target ... Not necessary for Big Game handgun hunting...put your money in a good Red Dot/Scope and shooting sticks.

    As a footnote: Commercial ammo is often geared for the shorter 5" 10mm barrels, hence slower burning powders that require a longer barrel to be efficient aren't used. In my experience, you can expect about 45~50 fps per inch increase using the 7" KKM barrel with factory ammo. If you reload, using slower burning powder, such as AA#9, can yield as much as 100~105 fps per inch increase. (https://www.glocktalk.com/threads/10mm-bear-loads.1778950/)
     
    Last edited: Oct 22, 2019