9mm Accuracy & Velocity

Page 3 of 5 Previous  1, 2, 3, 4, 5  Next

View previous topic View next topic Go down

9mm Accuracy & Velocity

Post by beeser on Tue Jan 27, 2015 9:42 pm

First topic message reminder :

Everything that I've read on this forum indicates that 9mm has to be pushed fast to be accurate.  Why is this when .45 ACP and .38 Special seem to perform fine at much lower velocities?    This doesn't make sense to me.

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down


Re: 9mm Accuracy & Velocity

Post by james r chapman on Sat Apr 18, 2015 4:15 pm

Well, 147 gr xtp's and 3.9 gr WSF(not WST!) gave me 930 fps.

contemplating how to go lower....


Last edited by james r chapman on Sun Apr 19, 2015 2:54 pm; edited 1 time in total (Reason for editing : wrong powder!!)

james r chapman

Posts : 1596
Join date : 2012-01-31
Age : 67
Location : HELL, Michigan

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by james r chapman on Sun Apr 19, 2015 2:52 pm

down to 3.5 gr's WSF, 850 fps...

james r chapman

Posts : 1596
Join date : 2012-01-31
Age : 67
Location : HELL, Michigan

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by robert84010 on Wed Apr 22, 2015 3:39 pm

OldMaster65 wrote:I was offered 2800.00 for mine. Turned it down. There were good buys on them even a year ago but they are getting harder to find.

Len


147 gr XTP. Still room to improve.



As I type this there are 6 for sale on GB. not cheap of course.

robert84010

Posts : 267
Join date : 2011-09-21

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Apr 22, 2015 4:41 pm

I sort of lost interest and gave up on the 952 as prices now seem to be more in line with collector pieces.  I'm satisfied for now playing around with the Range Officer in 9mm and just purchased another Pardini SP in .32 ACP for a more serious effort into centerfire.  I would still like to get a 952 but will wait for the right price one to come along.

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by LenV on Wed Apr 22, 2015 4:51 pm

The one I told you about is/was the best price I have seen. Adds like this one make me feel good about saying "no thanks" but wow..

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=479712494

LenV

Posts : 1729
Join date : 2014-01-25
Age : 66
Location : Oargun

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by james r chapman on Wed Apr 22, 2015 5:08 pm

147 xtp, 3.0 gr WSF, 724 fps......need a spring, lol

james r chapman

Posts : 1596
Join date : 2012-01-31
Age : 67
Location : HELL, Michigan

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Apr 22, 2015 5:32 pm

OldMaster65 wrote:The one I told you about is/was the best price I have seen. Adds like this one make me feel good about saying "no thanks" but wow..

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=479712494
Wow indeed!  But a pie in the sky ASKING price in my opinion.  I would turn my attention toward a Sig P210 long before reaching that price.

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Apr 22, 2015 5:35 pm

james r chapman wrote:147 xtp, 3.0 gr WSF, 724 fps......need a spring, lol
What platform are using for these bullets?
What kind of groups are you getting?
How low do you expect to get?

BTW  Congrats on the clean PPC 60 shot course!!!!

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by james r chapman on Wed Apr 22, 2015 6:00 pm

just in the testing phase for velocity right now. I'm where I wanted to be.

at 724 it stove pipes, so I'm waiting on some other springs n' things before I see if it has viable accuracy. It's a super light recoiling round that's for sure.

james r chapman

Posts : 1596
Join date : 2012-01-31
Age : 67
Location : HELL, Michigan

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by GrumpyOldMan on Wed Apr 22, 2015 6:53 pm

beeser wrote:
OldMaster65 wrote:The one I told you about is/was the best price I have seen. Adds like this one make me feel good about saying "no thanks" but wow..

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=479712494
Wow indeed!  But a pie in the sky ASKING price in my opinion.  I would turn my attention toward a Sig P210 long before reaching that price.
MMmyeahhh.... "Collector's Dream" if you're the collector selling at THAT price.

Don't think there is anyone gullible or motivated enough for it to sell at that price for at least 3-6 months if not for years.

Dream on, you collector. In my book that seller's just a greedy, mercenary jerk.

GrumpyOldMan

Posts : 452
Join date : 2013-03-08
Location : High Desert Southwest Red Rock Country

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Apr 22, 2015 7:47 pm

OldMaster65 wrote:... I just ordered some 115gr SWCBB from Penn that I am going to play with and see if I can work up a load for.

Len
Len,
Any updates on the 115 gr. Penn bullets?

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by LenV on Wed Apr 22, 2015 8:25 pm

Beeser ,
  When they got here I sent some to DrDon. I had a full plate getting the 40 cal (bullets came at same time) working the way I wanted. DrDon is working with his prototype barrel and I was curious how they would work for him. I haven't loaded a single round yet. I did make a seating die insert that wouldn't try to make a round nose out of it and I am ready to go now. Put the dot on the 40 today so should start on the 9's next week. I hope. Maybe..

LenV

Posts : 1729
Join date : 2014-01-25
Age : 66
Location : Oargun

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Apr 22, 2015 8:53 pm

OldMaster65 wrote:Beeser ,
  When they got here I sent some to DrDon. I had a full plate getting the 40 cal (bullets came at same time) working the way I wanted. DrDon is working with his prototype barrel and I was curious how they would work for him. I haven't loaded a single round yet. I did make a seating die insert that wouldn't try to make a round nose out of it and I am ready to go now. Put the dot on the 40 today so should start on the 9's next week. I hope. Maybe..
Sounds like a full plate.  Let us know when you get around to the 9mm Penns.

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by Dr.Don on Sat Apr 25, 2015 10:09 am

Full plate here too.  I will get to the Penn 115's in the 12 twist barrel soon I hope.

Dr.Don

Posts : 346
Join date : 2012-10-31
Location : Cedar Park, TX

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Jun 10, 2015 9:24 am

Dr.Don wrote:Full plate here too.  I will get to the Penn 115's in the 12 twist barrel soon I hope.
Get to the Penn 115s yet?

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by Dr.Don on Wed Jun 10, 2015 10:15 am

Yes, I did finish my tests of the Penn 115's.  They did not do well out of my 12-twist barrel.

Dr.Don

Posts : 346
Join date : 2012-10-31
Location : Cedar Park, TX

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by Jerry Keefer on Wed Jun 10, 2015 11:14 am

Re read this thread. Interesting calculations.
The 38 HBWC weighs 148 gr.. I am not surprised the 115 gr projectile did not fare well..
My 9mm testing was done mostly in 2001.. The light weight projectiles did not do well.. The 147s out of the 1X16 barrels did quite well.. We tried the 32 twist, but the shooters themselves, requested the return to the 16 twist barrels..
Convert the RPMs to Revolutions Per Second, and I think it is easier to envision. And ultimately, how fast is the bullet spinning as it passes thru the target? It's like a AA/F dragster.. The engine only revolves approx 540 revolutions light to light, but it is spinning almost 10,000 rpms light to light.. If the bullet isn't spinning fast enough to be stable, it will not be accurate in terms of ultimate group..

Jerry Keefer

Posts : 999
Join date : 2012-01-02
Location : Maidens, VA

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by GrumpyOldMan on Wed Jun 10, 2015 11:59 am

Not only do I not follow you, I am pretty sure that the effect of bullet travel on rate of rotation is so negligible it is practically nil--subject to mathematical calculation but so tiny as to defy in situ measurement.

I still await some more definitive testing and perhaps analysis of this. Similar bullet weights between the HBWC .38s and the (presumably) JHP 9mms, but there are opposite offsets of center of gravity and I suspect also vastly different centers of pressure on the aerodynamics side.  My suspicion since I was a pup and learned the difference between WC and SWC is that it is super-easy to make a generally cylindrical shape gyroscopically stable and a reasonably square front face minimizes any tendencies to hook or slice or whatever you want to call it from merely traveling through the air. Make it pointy and reduce the bearing surface and there arise many more opportunities for shape defects to screw up the bullet's flight, beginning with release from the case and engagement with the throat.

All nice in theory but all my attempts at seating depth adjustments in 9mm (like loading long to get closer to the lands, etc.) have had no reliably measurable effect. So I guess it's time to get a real barrel since 4 different OEM guns have failed to respond to massaging the ammo.

I even tried loading the 115 FMJs lighter, duplicated others' known loads, and still no joy. This latest with a SIG.

GrumpyOldMan

Posts : 452
Join date : 2013-03-08
Location : High Desert Southwest Red Rock Country

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by Jerry Keefer on Wed Jun 10, 2015 5:38 pm

Well, how about a football.. A fast spinning pass is far more stable than a slow spinning wobbling pass.  The barrel gurus say the lowest twist that will stablize the projectile is perhaps the best selection, but it is better to err on the side of fast twist..
Don't know what else to say.. I have been spinning them fast for 40 years, and it has always worked in my favor...

Jerry Keefer

Posts : 999
Join date : 2012-01-02
Location : Maidens, VA

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Jun 10, 2015 6:11 pm

Jerry Keefer wrote:Well, how about a football.. A fast spinning pass is far more stable than a slow spinning wobbling pass.  The barrel gurus say the lowest twist that will stablize the projectile is perhaps the best selection, but it is better to err on the side of fast twist..
Don't know what else to say.. I have been spinning them fast for 40 years, and it has always worked in my favor...
Not true according to this ...


beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by r_zerr on Wed Jun 10, 2015 6:37 pm

Jerry,

I have been contemplating on this and perhaps I can share what I have worked out.  With bullets, break things into two forms of stabilty:dynamic stability, which includes gyroscopic effects, and aerodynamic.

The fact that the bullet gets sent down range pointed the way it does, along with gyroscopic forces from twisting help keep it pointed that way.

However, for aerodynamic stability the center of pressure coming from wind drag and lift must be behind the center of mass. Unfortunately, wadcutters have a very square face with no rounded corners and this causes the air to be turbulent and swirl around the front edges, separating it from the bullet and not permit skin drag from the body of the bullet. This makes the center of pressure being very far forward, so in this respect, they want to turn themselves around. This doesn't happen right away, because of the other gyroscopic forces.

The shorter the bullet (light bullet), the lower the gyroscopic forces, which is what I believe is happening with the light wadcutters poor accuracy that I asked about previously.  I think that there is some faster twist rate where one can get those lighter wadcutters to stabilize, but it seems faster than what has been reported so far, and likely faster than practical

By the way, in keeping with the center of mass being in front of the center of pressure, this seems to me a good explanation of why hollow base wadcutters remain more stable than the solid ones. Also, the gyroscopic reactions increase when you move the mass of the bullets to the outside (HBWC vs. Solid WC). 

I am like you, thinking of the conventional information that says the twist rate should be enough for the bullets you shoot, but excessively more is not always helpful. That twist rate may not be very practical for lightweight wadcutters.

In regards to long vs. short bullets, bearing surface (length) and the jump from the case mouth to the throat and rifling is not included in the above statements. :-)

-Ron 

-Ron

r_zerr

Posts : 93
Join date : 2014-12-15
Location : El Paso, TX

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by beeser on Wed Jun 10, 2015 6:47 pm

Ron,
I apologize for my comment here before.  It has been removed.  It was not constructive to this topic nor your contribution to it.


Last edited by beeser on Wed Jun 10, 2015 10:48 pm; edited 1 time in total

beeser

Posts : 920
Join date : 2014-06-19

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by r_zerr on Wed Jun 10, 2015 7:02 pm

Yes, I suppose one can say that it is old school.  I am pretty old school now I guess ( I usually start with paper for my basic problem solving before stuffing it into the computer).  But if you have little or no drag at the back (caused by the subsonic turbulence), there are little or no forces (like what is provided by fins on a rocket or a long, thrown javelin), then wouldn't the very low forces of turbulent drag work against the desired effects?  Oh....and the blunt sharp nosed face of wadcutters is so very dominating in terms of the old-school drag that they appear very dominant in determining the center of pressure.

By the way, I am not saying it is so, but this is what my head has been able to absorb so far.  In other words, I am open to enlightenment!

-Ron

r_zerr

Posts : 93
Join date : 2014-12-15
Location : El Paso, TX

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by james r chapman on Wed Jun 10, 2015 9:34 pm

I think I need some Goody's Headache Powder....

james r chapman

Posts : 1596
Join date : 2012-01-31
Age : 67
Location : HELL, Michigan

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by Jerry Keefer on Wed Jun 10, 2015 11:58 pm

james r chapman wrote:I think I need some Goody's Headache Powder....
Smile I agree... some things are a lost cause..

Jerry Keefer

Posts : 999
Join date : 2012-01-02
Location : Maidens, VA

Back to top Go down

Re: 9mm Accuracy & Velocity

Post by Sponsored content Today at 6:43 am


Sponsored content


Back to top Go down

Page 3 of 5 Previous  1, 2, 3, 4, 5  Next

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum