First Shots KKM 13 Twist Barrel

First topic message reminder :

This morning I fired frame mounted Caspian 1911 with 13 twist barrel. I shot 3.7 BE 185, 3.4 BE 185 and 3.5 BE Brazos 160. Everything shot on call. 3.4 shot very forgiving at 50 yards. The 160 and 185 recoil felt identical. Target is 3.4 load. Using 10# recoil spring. I'm going to load up some softer loads and see how it shoots. I'm a slide mount guy, so this feels funny to me. Recovery is lightning fast. I've hardly been shooting but shook them in pretty good today.
I shot 95 & 96 SF, then 40 shots TF all clean. Best target 100-8x.
Looking forward to reduced loads next time out. Will be RR'ing in near future.
I think the faster twist really helped the 3.4 loads stabilize for 50 yds. In the past with 16 twist barrels its not very forgiving. Jerry Keefer was running 3.0 BE. Next time out I will try the same.
Jon

What made you switch from the Brazos 160s?

The Brazos 160's I previously shot were given to me (had 20 loaded rounds). I just got a shipment in to load up some with a lighter powder charge. So I was just shooting what I had on hand. In my experience so far with other pistols I can get 180/185 to shoot softer than 160's and give me better accuracy. Some pistols I've tried 160's in didn't group as well as the 180/185's. So I'm not sold on 160's yet. Still working it out.
Jon

Jon-

Thank you for sharing your experiment with us.  I have been intrigued with the idea of a fast twist .45 barrel since Mr. Keefer posted about it in 2016, you have now reignited my interest.  Since the reason for utilizing a 1:13 twist barrel is to impart a faster rotation on the .45 bullet so that it maintains flight integrity at slower velocities… it raises many questions.

.  Why 1:13?  I know Jerry had success with a 1:14 and reportedly made a 1:12 before he passed.  I do not remember him posting any 1:12 results.

.  What weight of mainspring/hammer spring are you using in your setup?

.  Have/will you measure the velocities you are achieving with your 2.7 and 3.0 grain loads?

.  The holes in your 2.7 target are a bit ragged, would a faster twist barrel improve that even more for that load, or is that more a function of velocity?

.  Have/will you compare the accuracy of the same loads fired from 1:13 & 1:16 barrels?  This would be very interesting but probably require a barrel-testing fixture.

.   Do you think it is possible to identify a velocity “threshold” where either twist rate has the advantage in accuracy at a given distance (i.e. 1:13 twist barrel is more accurate below 675 fps)?

.  Given the narrow velocity range (i.e. 150-250 fps) of typical bullseye loads, is it fair to say the powder load reduction possible, due to the faster twist 1:13 barrel, was less than the powder load reduction achieved by adopting a frame mount system?  In other words, the low velocity stability gains of the 1:13 barrel allows one to further refine their minimum viable charge.

I appreciate your comments and thoughts and look forward to your next update.

Scott

Good stuff! What equipment do you reload on?

Wow 2.7 grains of bulleye with a 160 grain bullet that is pretty amazing. I thought 3.7 grains of bulleye and a 185 grain bullet was a light load.  As for cutting clean holes I have found Kruger targets give a nicer hole with the slower velocity bullets.

Been busy building guns and not shooting mine. Just got out and shot the 13 twist again tonight.
Today I shot 50 yards with new load; 3.5 gr BE with Zero 185 JHP. They shot on call and clustered them nicely. Brass ejected about 3 ft to the right.
To clarify earlier post, my light 2.7 BE charge was with 180/185 lswc. My lightest 160 load was 3.4 gr BE. The 180/185 feels better too me than the 160. I also group them better.
Commiefornia has no matches yet in So Cal. My next match I plan on shooting these loads.
The 13 twist rifling has been intriguing. I think it will benefit woman and men with shoulder/arm problems. And my friends who don't like recoil would definitely like it.
Building more fast twist guns now, so we'll be hearing from others in the near future.
I still plan on machine resting the pistol and sharing the results.
Jon

I know I'm resurrecting this topic, but did you lighten the slide at all?

My memory is that Jerry was using a slide that had been lightened for PPC use on the 13 twist frame mount and that helped to get the 180gr Penn load working with 3.0.  I'm pretty sure that the 12 twist is on the last gun that he built for his shooter.

The slide has not been lightened. Yesterday I was out shooting and ran 2.8 gr BE Summers 180 PB lswc through the gun without a hitch. Temperature in high 60’s. The pistol is very tight. Takes a lot of effort to unlock the slide by hand. I get a kick out of the fact that it will run these light charges and still be so tight. 25yds is cake with this pistol. I have not been shooting much so I still need to see what the lightest 50 yd load can be. I have a 12 twist Douglas barrel I need to fit to one of my other guns. 
Jon

I can't wait till my KKM 1:13 barrel gets in...just seems to be taking a while...but I guess that's kind of the times we live in.

So I went shooting today and was having exceptionally good performance with my 22. I then was doing really well with the 13 twist 45 at 25 yds with 2.9 BE 180 Summers bullets. I decided, what the hell try 50 yds with the 2.9 load.
Here’s my target. I made WAG on clicks up and errored high. Did not spot my shots. They were on call when I checked my target; called the good and the bad
They felt that good but I didn’t think they would look that good considering the light charge. I was pleasantly surprised by the 7 shot cluster. 
The fast twist barrels are really forgiving to shoot. It’s been interesting playing with this gun/barrel combination. Next month I’m shooting my first match in almost a year, I will probably shoot this pistol.
Jon

Jon, that is really impressive at the long with that load. Is the gun a slide or frame mount?  Your hand must be feeling good again.
Stan

Frame mount Stan.
Jon

Jon Eulette wrote:I was using the coated bullets. 3.5 of BE was warm, the 3.4 with 185 didn't feel as snappy. I need to pick up more of them to download.
Jon

Brazo has two diameters to pick from .453 and .452. which ones do you use? They make both diameters for all of the 45 acp lead bullets. I am not sure which one to chose and why.

Thanks for your help.

99% of the time I use 0.452 bullets. Most 45 ACP barrels are 0.451 groove diameter. Typically you just go 0.001 larger than your bore with lead bullets.
Jon

Jon,
Is there any reason not to try the 1:13 with a slide mounted optic?  Or any advantage?

That’s in the works now Russel, I see no reason not to use with slide mounted optic. 
Jon

Update? Any downside at all to the fast twist barrel? Gonna be standards issue for all future builds?

Will be offering 13 and 16 twist per customer request. The 13 has shot everything well. It shines with low velocity charges. I have not had time to machine rest it yet. Looking forward to it.
Finishing up one for a forum member now with a frame mount.
Jon

Shot a NMC last night using 2.8 gr BE Zero 200gr lswc. 96, 100, 99. I’ll take a 295 at 1am using my headlights lol. Here’s my SF target.
Jon 

Very interesting. Wondering how low on powder charge can you go with 185 JHP and still retain good accuracy at 50.

javaduke wrote:Very interesting. Wondering how low on powder charge can you go with 185 JHP and still retain good accuracy at 50.

Just getting started testing  , gun is a Caspian frame/slide , 17# mainspring ,9# recoil spring , Bo-Mar sights. Several fellow shooters in the area are interested in this experiment, so I'm using standard  , off the shelf  , springs ,etc. to be repeatable for other shooters. I've loaded up several different powders with different charges to see what functions , and 5 round groups on the Ransom Rest to test accuracy potential. I know , 5 rounds aren't statistically significant , I'm doing preliminary tests to eliminate combinations that don't show much promise , without wasting a lot of time or components. All loads are Zero 185gr JHP , WLP primers , TZZ cases , 1.205 OAL , crimped to .465". I think the WLP and .465 crimp might be helpful in getting the best combustion at these low charges and pressures. So far , 3.6 and 3.4 of BE are showing identical groups of 1.75" and I think I can go lower , still snappy. 3.6 of N310 was 2" , 3.4 opened to 2.75". 3.7 of TiteGroup was 2" , 3.6 & 3.8 both opened up to 3.5". 3.4 of 700X was 4', vertically strung , 3.3 was 2.625". WST was 2" at 3.8, 2.25" at 3.6 and 2"at 3.5. Interestingly , 3.6 had 4 shots into 1.38" with the 1st shot low opening the group to 2.25". I suspect operator error loading the 1st round. All groups fired at 50 yds. The bottom end loads are finicky re: reliability , if you don't hold hard , they fail to eject. I was shooting off hand at 25 yds for reliability tests , if I slipped up and dropped an 8 , it probably also failed to eject. You need to provide a solid platform to recoil against. In the Ransom Rest , everything was reliable. 4.2grs of WST fired the same groups with the 1:13 barrel as my Kart barreled ball gun , 2".  Overall , 5 different powders , 13 combinations , 65 shots total , only one round would have missed the 10 ring. More testing to follow. I've also got 7 and 8  # recoil springs coming to improve reliability.

I've done some more testing and had a couple surprises. 3.3 Bullseye or 3.6 WST w/ a Zero 185JHP seem the best , < 2" @ 50 yds . Tite group and N310 didn't do as well . It seems that any reasonable load w/ BE or WST will keep everything well inside the 10 ring whereas TG or N310 will keep shots touching the 10 ring. Also , even thought they still felt snappy , FTEs started to occur with those powders before recoil got down to the levels achievable with BE or WST. Zero 185 LSWCHP worked well at 3.0 BE or 3.4 WST. Keep in mind that bullet has the same bearing length as a 200 LSWC , hence the same air space in the case. While 3.0 was the lowest charge of BE with the 185 , I went down to 2.8 with the 200 gr bullet . I ran out of 200 gr bullets before finding the lowest charge of WST. I've often heard over the years that the lowest recoil is achieved with the 200 gr bullet, but this was the first time I loaded down until they failed to function . Also , most 185 Lswc have a shorter bearing surface , with greater air space, making direct comparisons difficult. The recoil difference was so pronounced I tried to duplicate it with Hornady 200gr XTPs , I can't say I had much luck , and given the lack of 200gr bullets that aren't at least double the price of Zero 185s , I didn't try too hard. They were satisfyingly accurate though. 3.4 BE was as low as I got with the Brazo 160 grs., but this gun doesn't seem to want to feed them, making testing difficult, I did get better accuracy than I did with my old ball gun, around 2.5 ". Summary , any reasonable load with BE or WST is a winner. The goal of the exercise is to find a load that will allow this Grand Senior to continue shooting without recoil aggravating my shooting arm to the point of losing the ability to fire the gun accurately. Time will tell , but it seems apparent that I've got less recoil than ever before , without sacraficing anything in the accuracy dept. The other lesson is that all of this mirrors Jon Eulettes' previous posts. I could have saved myself a lot of work if I'd just followed his obsevations.

Richard your testing with the Lead Zero 185 bullet is very close to what testing I did with my 1-13 slide mount gun..for my gun 3.4 of WST worked at the long line and 3.1 was fine at 25yds using a 180 Brazos coated bullet  
3.1 of BE worked at the long line with the 180 Brazos.  

keep in mine I had a slide mounted H1 copy on my gun but had lightened up the slide a bit with some cuts under the rail.. still pretty close to what you saw. we ran a 9lb and 10lb spring at times..


you know the testing was fun....

Wow, thanks, Richard, this is very interesting, as I said. Looks like the load I'm looking for would be 3.5-3.4gr BE and 185gr JHP. Very tempting. I'm sure I still have a spare frame and slide somewhere deep in my parts bin, perhaps I can build a "ball gun" tuned to this load. 
If I understand correctly, the only manufacturer so far who makes 1-13 .45ACP barrels is KKM, correct?
Also, have you measured the muzzle velocity? I suppose with the above mentioned load it must be something close to 700fps, or maybe even below 700.

javaduke wrote:Wow, thanks, Richard, this is very interesting, as I said. Looks like the load I'm looking for would be 3.5-3.4gr BE and 185gr JHP. Very tempting. I'm sure I still have a spare frame and slide somewhere deep in my parts bin, perhaps I can build a "ball gun" tuned to this load. 
If I understand correctly, the only manufacturer so far who makes 1-13 .45ACP barrels is KKM, correct?
Also, have you measured the muzzle velocity? I suppose with the above mentioned load it must be something close to 700fps, or maybe even below 700.

I don't have a chrono , and really don't care about the velocity , only accuracy and recoil. However , the Midway LoadMap lists velocity for 4.3 of BE with a Sierra 185 JFP at 655fps.I wouldn't be surprised if these loads go under 600fps. I also didn't repeat any tests with 700X , which gave poor results in my initial testing. The can had a price tag of $5.50 and no barcode anywhere. I suspect I've had it since the Reagan administration.  My barrel came from KKM , but I believe Jon posted something about having a 1:12 barrel from Douglas