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WA1500 Twist Rate of Barrels

December 29 2016 at 3:18 AM
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Andrew  (Login spEKTre)

 
I am just asking around as to why gun builders these days recommend a 1:24 twist barrel for both Revolver and Pistol ? instead of the 1 in 16 twist.

 
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Jim C
(Login jamesrchapman)

Re: WA1500 Twist Rate of Barrels

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December 29 2016, 8:55 PM 

would you mind stating which gunsmiths???

If your speaking .38 specials, I think it's been pretty clear that 1:10-1:14 covers the requirement pretty well...

Jim C

 
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Andrew
(Login spEKTre)

Re: WA1500 Twist Rate of Barrels

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December 29 2016, 9:01 PM 

Gunsmiths here in Australia like Max Wray and Ray Pulver recommend 1:24 for WA1500 for some reason and I want to understand why ?

 
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Unregistered Member
(Login jamesrchapman)

Re: WA1500 Twist Rate of Barrels

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December 29 2016, 11:07 PM 

It's possibly the use of ultra light (100 gr) bullets.

 
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Andrew
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Re: WA1500 Twist Rate of Barrels

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December 30 2016, 12:01 AM 

I have an STI with a 1:24 Pulver bull barrel and it seems to only really like the 100gr SWC. I guess I have never tried the 115 FMJ as my range does not permit Jacketed bullets, so I haven't tried everything yet. It's interesting because they don't stabilize till just over 1050 FPS and from a rest hold about a 1.5" group @ 50 Yards. I did manage to get some 125gr Conicals to group under 1" @ 50 yards but they didn't even come close to cycling the gun.

 
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JB
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WA1500 Twist Rate of barrels

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December 30 2016, 12:02 PM 

Interesting, I have a STI Targetmaster with 6" bbl. They are 1:16 and when I first got it couldn't get it to shoot better than 6"-7" at the 50 out of a Ransom. Sent it back to STI twice and they replaced slide, then finally bbl and I am getting 2"-3" at 50 now with 115 grain JHP Wincheser boolits. They wont tell me what bbl they are putting in them, but whatever it is quality something to be desired(at least one I got)Now I know why the person I bought it from sold it. Shame, it is a solid well built pistol, but lacks ability in what it is supposed to do. Must say their customer service was top notch. Everyone I have since talked to that had one has changed the bbls in them. Several said the lower end Trojan shot better than the Targetmaster.
As heavy as the slide is have to load them up around the 1200fps to get the thing to function, but recoil still mild with all the weight. If I keep it, might have to invest in another bbl, but hate doing this to a gun that is supposed to have performed good to begin with. I know my shooting prowess has depreciated, but out of a machine rest, as someone stated previously, takes the stoopid factor out of the equation,it should perform.
In the past we have tried some 90 XTP's grain JHP boolits out of the PPC9 and Targetmaster and they were all over the place.Maybe need to try some of the 100 grain lead SWC in the Targetmaster.

 
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Hatman1793
(Login Hatman1793)

148 grain FWC's work just fine.

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December 30 2016, 10:59 PM 

It appears to me that a much slower barrel twist rate is not an advantage.

First is obtaining very light FWC light bullets. Most of the big commercial casters make 148 grain lead bullets for target...and they work very well. Plus, try & finds swagged lead 100 grain bullets.

Two. A much slower twist rate as suggested goes against the grain (pun intended!) of what most PPC revolver shooters know. And have proven.
It is much easier to use a faster twist rate and a lower velocity for 148 grain FWC's to achieve accuracy, than push a much lighter bullet of whatever construction at a higher velocity. It appears that a faster moving light FWC has little time to really stabilize in flight. Plus, this much lighter bullet will have a significantly smaller driving band to create accuracy with such s slow spin. It appears that this concept is entirely anathema to accuracy.

PPC is all about timed accuracy, & has no power factor. PPC revolver shooters have solved the accurate load problem. It is the human operator that determines winners.....


 
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Andrew
(Login spEKTre)

Re: WA1500 Twist Rate of barrels

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December 31 2016, 1:49 AM 

JB
I had no success with anything but the 100gr SWC in my STI, its a 1:24 twist Pulver BBL with a "Nose Cone" bolted onto the front of the barrel and there is no bushing so the end of the slide face locks up against the end of the block on the barrel as you can see below. Very tight lock up and a noticeable clunk when the slide batters forward which takes some getting used to but it will go sub 1.5' off a sand bag.




[linked image]

 
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Tony
(Login tonyk1960)

Barrel twist rates

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December 31 2016, 3:13 PM 

Interesting discussion once again, it seems that there are as many different reasons to try as many different twist rates as the dollars would allow. Is there an optimum twist rate? I had a copy of "Hatchers notebook" a number of years ago (lent and never returned) but in there he talks a lot about stability in flight, and gives a formula to work out the optimum length of projectile for a specific twist rate. Not being a physicist but I am sure if I had that formula in front of me I reckon I could work out the twist rate required to stabilise a specific length of projectile. Now that's a project for my spare time.

I have heard from a lot of people that they couldn't get their STI's to shoot, unfortunately over in Aus it's a little difficult to send it back to the factory, that is why we have so many aftermarket barrels available, and no-one I have spoken to has been able to find the manufacturer of the barrels either.

I think we are all aware that the original PPC round was a 148HBWC and it was the foundation of many a great score, and still is. Finding a good manufacturer these days is hard, but they are there and we keep them going strong. With the decline in this style of target shooting (PPC and ISSF) and the rising of IPSC and Action pistol where "fast is best" has lead to a new breed of projectile coming out and the manufacturers catering for that is causing the shortage we all feel. I won't get on the soapbox about powders and primers either.

So optimum twist rate for PPC, does yours work? If it shoots good groups that you are happy with then it's the right twist. If someone gave me a barrel with a 1:50 twist, I have a spare gun to try it on, but wouldn't just go out and buy a barrel because it's there and available. My 1:8 shoots fine, I've shot everything from 100SWC's through 148HBWC's to 160 HBWC's for our Service Pistol match to make power factor, even shot Action with them with some success.

Ultimately, it's the nut on the butt. There is no substitute for skill.

Happy New Year to you all and looking forward to some great discussions this year

Tony

 
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JB
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Twist of rate barrels

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January 2 2017, 1:36 PM 

Andrew,
Interesting that you are able to use the 100 SWC's in this bbl with such good results. Can you tell me what your "load" is for this bullet, COL, etc?. Are you getting reliable function and lock up? Did you "chrono" the loads?
LIke Tony says, STI refused to tell me what bbl they are using other than it is a 1:16 twist.No one else seems to know what they are either.Fairly sure made in Phillipines since their lower end guns made there, but could be in error. The one they replaced it with likes Winchester 115 JHP the most with 4.2 CFE powder, 1.142 COL so far. Cant load it down too much with the weight of slide will not function.You can see slide moving forward almost slow motion, and do clunk on lockup.Does lock up tight. HOw is trigger on yours? Mine breaks about 4.0 lbs no creep.
Just curious, sights appear to be Aristocrat, and wondering if your adjustment screws are metric or s.a.e.? Mine has metric,and Jim @ Aristocrat swears his only come with s.a.e. Had to have the front sight replaced for a higher one for neck shooting at 50. Stock sight could only shoot point at 50, this way it came.
BTW, like the furniture on yours. I picked up a nice set of Rosewood with finger groobs on Ebay made in Phillipines I think.

 
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Andrew
(Login spEKTre)

Re: Twist of rate barrels

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January 2 2017, 5:44 PM 

JB
I'm currently using 2.60gr of AS30N + 100gr Spartan SWC @ 1.035 ( short I know ) and I had major issues using Win brass but swapped to all new Starline and feeding problems disappeared straight away. The lockup is ok but after about 200+ rounds I can get some issues because the chamber is pretty tight. The loads chrono at between 1030 and 1050 fps, its interesting because below those speeds the groups open up quickly off the sand bag.

My STI has a definitive clunk when it batters which is annoying but has the advantage of letting you know if a round gets stuck and doesn't chamber, the trigger is ok its closer to 3lb than 4lb and practically zero creep ( I made up a trigger stop screw with a rubber insert ). The rear sight is aristocrat but the front is a custom steel block grub screwed onto the barrel, the screws are definitely imperial.






 
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JB
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Twist rate of bbl.

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January 2 2017, 6:53 PM 

Andrew,have you tried AP70N powder? The ADS30N not listed until you get to 115 grain boolit. I see where this powder comparable to some Hodgen powders and loads.ADI now Thales Powder.
On the Spartan boolit, is it polymer coated or copper wash? What diameter are they.355 or .356?
You should be good at the 1050 fps mark if it functions gun.Might do even better little faster.
In our matches if the trigger wont lift 3.5 lbs they DQ it. A machinist made up my front sight to fit the factory dovetail in the slide.My adjustment screws are definitely metric. Might be a copy.

 
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Andrew
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Re: Twist rate of bbl.

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January 2 2017, 10:29 PM 

I have tried the AP70N but found the lighter loads tend to spit out unburnt powder but it is really soft to shoot. The spartans are polymer coated ( green ) and are .356 and after some more test this morning anything under 1050 fps and the groups open up, I'm thinking of trying 1100fps to see if it gets tighter or stays the same. Had no joy with the 2.1gr Bullseye 100gr SWC out of my 1500 revolver but, thinking because my twist rate is 1:16 that it needs to go faster than the 700fps to stabilize.

 
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Tony
(Login tonyk1960)

Twist rate

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January 4 2017, 3:38 AM 

Hey Andrew, I'm running 2.9gr of AP50 through mine at present wit the 100SWC's, soft but groups OK at 50yds. Anything under that and it's a one hole group. Over the chrono it's just running a little over 1000fps (as you are), I haven't done a lot of work with the 9mm as it's purely for fun for me.

I'm running .357 spartans, exactly the same as my revolver. It's not true that I am lazy, just frugal wink.gif

I couldn't get AP70 to shoot and as you found also that there was too much unburnt powder. When I ran out of my tin of 473AA I ran AP30 for a while with 3.2gr but as I had 6 tins of the 50 decided to give it a go. It fills the case up to the base of the projy and meters fine through the Dillon so it's a bonus, plus it's around the same burn rate as the 473AA.

I have found with my service loads that AP/AS30 will give fantastic consistent results in a 3.0 to 4.0gr load but due to it's coarseness will not throw consistant small charges. I do know someone who uses it in their 32S&W, and was until recently in the NSW team, but he doesn't throw them, each one is measured.




 
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Andrew
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Re: Twist rate

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January 4 2017, 6:05 AM 

Tony your dead right about the small charges, I managed to get 2.1 to throw very reliably in an old Lee Pro 1000 press with the grey half disk's. For some reason the Lee Auto disk with a large hole works well with AS30N. My Dillon XL650 won't do that, as with some other complaints about it my original reloader in the Lee does many things better. I scored 3lbs of Bullseye today so I'm a very man today happy.gif

Testing out some loads tomorrow in the 9mm hopefully pushing the 1100 fps from a sandbag just to see what happens with the group sizing.

 
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JB
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Twist rate

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January 4 2017, 11:39 AM 

If you can get some Nobel Vectan BA9 you might want to try this:
Reload (9 mm Parabellum (9 Luger) (9 x 19) / Ba9)CIP RULESLength [mm]19,15Pressure [bar]

2350BULLETTypeJRPWeight [g]6.48Weight {[grs]100 grains} PRIMER PrimerSmall

PistolPOWDER PowderBa9STARTING Load
: [g]0.24Weight [grs]3.7Velocity [m/s]331Velocity [fps]1088MAXIMUM LOADWeight [g]

0.30Weight [grs]4.6Velocity [m/s]370Velocity [fps]1213

This stuff meters great.

There are 9mm loads for BA10 also for 9mm, but faster powder burn similar to BE. BA9 recommended for 9mm.
Just suggestion you might want to do some research on

 
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Tony
(Login tonyk1960)

Twist rate

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January 4 2017, 2:33 PM 

Thanks JB, I haven't seen Nobels powder in Aus since the '80's when I bought a can of Revolver No 1, I still have the unopened tin. Unfortunately we are stuck between the rock and the hard place, a shortage in the US means an extra shortage here.

ADI/Thales manage to export most of their powder these days over there and re-badge as Hodgons, apart from the "small fire" they had in one of their production lines we have been promised a replacement for AP30 for two years now. If you can find the other ADI powders then if it works you grab it. Winchester powder is scarcer than hen's teeth, we have a plant down in Melbourne but they don't produce powder, go figure. Alliant is just if not more difficult to get hold of so we buy big. Vihtavuori powder is few and far between, and enormously expensive.

That is why we tend to be experimenters over here, make something work. I know someone with a tin of WAA Lite that I may pinch and see if I can get that to do something in the 9mm, at least I can buy quantity.

I won't get started on primers.....

But thanks for the heads up on Vectan, you never know.

cheers

 
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JB
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Twist rate

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January 8 2017, 5:10 PM 

Andrew,
How did you do with your testing with the BE?

 
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Andrew
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Re: Twist rate

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January 23 2017, 8:34 PM 

Sorry JB didn't see your question there, Bullseye is too quick for my STI mate. It seems that its the wrong powder with the weight of my slide, I've had several goes at using it and even up over 3.3gr it won't cycle properly.

 
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JB
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Twist rate-Andrew

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January 23 2017, 9:09 PM 

Too bad. Here is what I came up with 3.9 grains of CFE pistol powder using a Missouri hard cast 105 grain seated 1.050.Shot great out of the STI and PPC9. the Hi-Tek coating shot tightest. I did not chrono it yet. When I do will give you feedback. Hopefully will be able to get out tomorrow.
Burn rate just above V3N37 and N350 for reference.
Do you have the factory spring in your STI? Little surprised that it did not work the slide for you. What other powders do you have access to?
Cant get these lighter bullets to shoot worth a poop yet out of my .38 yet.
Thanks for the reply to my inquiry.

 
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