Need help with 10mm match loads!

[Idaho45guy]

Shot in my first GSSF match last month and the next one is next Saturday.

In the first match, my pistol was stock other than a fiber optic front sight and a Pearce grip extension; both legal for Stock class. I shot the stock class first but was so nervous I flubbed it and got a 427. I calmed down and they let me shoot in Unlimited with the stock G29. I did much better and got a 468.

What killed my score was the 25yd distance; 10 shots in 15 seconds. The 10mm is snappy, and the load I chose was my most accurate but had some heat to it. I simply couldn't get back on target and reacquire a proper sight picture in 1.5 seconds.

I ordered a new Lone Wolf conversion barrel to turn my 10mm into a .40 S&W for the Unlimited division. I developed a few different recipes, but when I went to the range, it wasn't accurate with any of them, including factory loads, so I sent it back to have it looked at.

I had also ordered a KKM Precision 4.5" 10mm barrel for shooting cast with and it arrived yesterday. I also went to town and discovered that my LGS finally had some Blue Dot powder that folks had recommended. I put together some very mild loads using it and both Hornady XTPs and my 180gr RCBS cast boolits.

Today I shot around 10 different recipes using WSF and Blue Dot and the cast boolits and XTPs in both stock and KKM barrel. KKM barrel was underwhelming in both accuracy and function. Several FTF jams and magazine rarely will lock back after last round is fired. At this point, I can't use it in a match.

It had feeding issues and failure to lock back slide with factory HSM ammo. It did turn in the best group of the day with a 2 3/8" at 25yds. But, the stock barrel was not far behind at 2 1/2".

What was surprising was how much more recoil there was with Blue Dot mild loads compared to WSF mild loads. Factory HSM 180gr cast boolit loads were middle of the road in terms of recoil and not very good with 4" groups.

Best group was with 180gr cast boolits and 9.6grs of Blue Dot, but they were very snappy compared to the same boolit with 5.2grs of WSF.

Stock barrel and 180gr XTP with 5.2grs of WSF was reasonably accurate at 2.5", and the recoil wasn't bad, either. So far, it is my preferred match load for the stock class.

It's trying to figure out this KKM barrel and finding a combo that is both low recoil and accurate.

Honestly, the FTF issues have me concerned. Most folks say their KKM barrels are drop-in and 100% functioning with everything. Could it be more sensitive to limp wristing? When I bench shoot for groups, I have a very loose grip, which has never caused a problem with any other pistol or load, and when I tried the Lone Wolf conversion barrel, it was 100% functioning, just not accurate.

The powders I have on hand are WSF, Unique, Titegroup, Blue Dot, and Lil' Gun. In previous loads, TG was not very accurate with either the XTP or cast boolit.

WSF is milder recoiling, but not as accurate as Unique or Blue Dot.

I don't have but a day or two of load development available before I shoot in the match. Suggestions for what load to try next for the KKM barrel? Or should I think about sending it back due to the feeding issues?

I took some pictures of it and the stock barrel after shooting today and before clean up. I didn't notice any unusual wear marks...

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[TXCOONDOG]

I had a Glock 20 with a KKM barrel and shoot the 10mm weekly. I don't shoot in any competitions but I do shoot 25yards and beyond as I hog hunt with the 10. I have small hands and short fingers so I struggled a bit staying consistent and installed a different trigger with a lighter pull and shorter reset. I since switched to a 1911 and keep most of my timed freehand shots in a 3"-4" groups at 25yards.

I tried all the powders listed except Unique using the 180/200 xtp and now I'm casting my own.

I use Longshot for my range loads and AA#9 for my hunting loads (1300 fps w/200 and 1385 w/ 180). My records indicate that 7 gr of LS with a WLP primer gave me around 1065fps (200 xtp) in the G20 with the KKM barrel and 2" groups at 25yards with reliable function.

Edit: KKM barrels have tighter tolerances compared to Glock and why you may be having FTF and COL can make a huge difference. At one time Wolff had came out with a SS (added weight/less muzzle flip) dual captured guide rod and you can change the springs, but not sure what is allowed so just an FYI.

I'm in a 700 member shooting club and shoot with some outstanding shooters. I don't like loosing to anyone, therefore I don't shoot competitively as I would end up broke always looking for the extra edge.


Good Luck on your quest for the right combo.

[TXCOONDOG]

Just something to consider:

If I was shooting in competitions than I would send my barrel to DougGuy and have him throat, crown & polish. Had him do this to a Storm Lake barrel for my M&P as the crown was off center.....what a difference it made.

I'm sure Doug will be along shortly.

PS: Keep in mind that if you send the barrel back to KKM and it meets thier tolerences than you are out additional time, shipping, etc.

[contender1]

I am not a Glock owner,,, but I do have almost 20 years of USPSA competition under my belt.
One thing I do to ALL my 9mm, 40 S&W, & 45 ACP ammo is check all the loaded ammo with a chamber check gauge. (Midway, Dillon, Wilson,) This has allowed me to have almost zero failure to feed issues.

As for loads,, I use Xtreme plated bullet. I'm using Unique powder,,, and to make "major" power factor,,, I use 5.6 grns, with WW primers. I'm using a S&W 646 revolver in 40 S&W. (I won revolver yesterday at our local match.)

As with any loads,,, experimentation will be necessary to find an accurate load.

I hope my meager thoughts help you some.

[DougGuy]

How hard are the boolits you are using? It plain sounds to me like the boolits aren't getting a good fitment in the bore for one, which could be caused by too hard an alloy over a mild enough charge to not cause them to obturate fully. You don't mention whether there is any leading or not. You also don't mention boolit size or COA.

The 10 is like the most magical feeding cartridge there has ever been invented for an autoloader. Feeding problems with a 10 are usually easily diagnosed and fixed. They DO like the boolit seated out longer, and if you are seating deeper so they will plunk, this can introduce 3pt jams as the rim comes out of the magazine lips before the nose of the boolit is against the barrel and it is not stable.

FTF can occur if the case is not seating fully in the chamber b/c the boolit is jammed into the throat, and firing pin energy is wasted by pushing the case forward by the primer. How much freebore do you have ahead of the leade ins to the rifling? What diameter is the freebore, what are you sizing to?

I would be glad to throat and crown the barrel, polish the feed ramp, this is about the best you can do to for getting the COA you want to use, to work well. Between throating the barrel and using a softer alloy and soft lube you should be getting much smaller groups.

[Groo]

Groo here
I tried a G-20 in Ipsc. [ had used my G17 gen1 [with 147 bullets] for almost 2 years]
Went clear down to 135gr bullets and a little over major reloads.
The gun was just too light, I believe a 45 would have the same problem.
I now have a G-40 longslide.
The weight is close to the same but the long slide changes the balance.

[Idaho45guy]

I noticed leading in the barrel last night and posted another thread about it in the Cast Boolits forum.

I slugged the barrel and it is at .400. My boolits are sized at .4015 and are of a harder alloy due to me still having a pot full of hard cast stuff for bear loads.

So, I need softer lead and to run the boolits without sizing them, which come out at around .403 to .4035, and to turn the heat up a little with cast boolits to get more accuracy, which is the opposite of what I need in a match.

What I don't get is that the barrel is inaccurate and unreliable with factory ammo.

XTPs are at .400 and my barrel is supposedly at .400...

Just slugged it again with an XTP and seemed plenty tight...

[TXCOONDOG]

My barrels always improved when a little fouled. I have actually lost accuracy with over cleaning. Obturation has also played a part in leading and accuracy issues (9, 38 special and 357)as already stated.

I just started casting for the 10mm and lead with a BHN of 16 works well for me but I load to near max and obturation is not an issue. For my .40 at 1,000 fps, lead with a BHN of 10-11 gives the best accuracy.

[Lloyd Smale]

had a lone wolf barrel on my 20. It like yours wouldn't run well. It was chambered to tight. It also didn't shoot as well as my factory barrel with lead. I sent it back and told them it was chambered to tight. they said it was right to spec but if I wanted it opened up they would do it. Well I got it back and it still had the residue in the chamber that was there when I sent it in so they didn't do squat to it. I sold it and went back to my factory barrel. Runs like a top and shoots, well as good as a glock. It isn't going to win any bullseye matches but with loads it likes it shoots a bit over 2inch at 25 yards.

[Idaho45guy]

Shot 115 rounds yesterday and the KKM barrel stopped having FTF issues. Still not real accurate but got it down to 2" at 25yds and very mild recoil by using 5.2gr of W231 behind a Hornady XTP and 5.2gr of WSF behind a 180gr RCBS boolit. Good enough for a GSSF match, for now.