Jump to content
Brian Enos's Forums... Maku mozo!

need advice on major 40 load


jimbullet

Recommended Posts

HI,

 

Just getting opinions please. So I have done a load of 5.3 grains on a 180 grain projectile and the raw data is as follows:

 

FPS

939

967

989

891

988

961

962

989

 

If I take the lowest three, it would not meet the required 170 PF. But if random choose each shot - it would.

 

When I go for 5.4 grains, the power factor is already at 180PF

raw data on 5.4 grain

1025

1006

1025

1019

1012

1003

1007

 

All test shot on 12 degrees Celsius cloudy day if that makes a difference

5 inch STI DVC Limited

 

Your thoughts please - would you use 5.3 grains in a major match?

 

 

Link to comment
Share on other sites

I tinkered with loads until I came up with one that made 172PF with SDs in the 4 to 7 range.   That puts every shot in a 10 or 20 round string well above the 165 floor.  I go 7 above the floor because chrono technique at matches is not always the best.  I want to have an extra margin.

 

!77PF is what I would shoot for in IPSC.  If my SDs were higher than 7, I'd go hotter.

Link to comment
Share on other sites

5 hours ago, jimbullet said:

HI,

 

Just getting opinions please. So I have done a load of 5.3 grains on a 180 grain projectile and the raw data is as follows:

 

FPS

939

967

989

891

988

961

962

989

 

If I take the lowest three, it would not meet the required 170 PF. But if random choose each shot - it would.

 

When I go for 5.4 grains, the power factor is already at 180PF

raw data on 5.4 grain

1025

1006

1025

1019

1012

1003

1007

 

All test shot on 12 degrees Celsius cloudy day if that makes a difference

5 inch STI DVC Limited

 

Your thoughts please - would you use 5.3 grains in a major match?

 

 

Jim,

There is some wide variation between those two loads. The ES/SD on the first is 98/33.2 while the latter is 22/9.4. You need to figure out why the 5.4 gr load has 1/3 the standard deviation of the first load! Even throwing out that 891, the 5.3 SD is still 2x the 5.4 load.

 

But in the general sense, you want to load 2 or 3 SD's above the required velocity. If your SD is 10 and your bullet is 180 gr, your load should yield 964-974 FPS. Also, be sure to check your bullet weight. There is a tendency to use the cheapest bullets around and you may find some weight variations. Weigh 20 or so bullets and calculate your SD for them and use the nominal weight minus 2 or 3 SDs to calculate your power factor when you chrono your next loads.

 

Later,

Chuck

 

Link to comment
Share on other sites

5 hours ago, ChuckS said:

Jim,

There is some wide variation between those two loads. The ES/SD on the first is 98/33.2 while the latter is 22/9.4. You need to figure out why the 5.4 gr load has 1/3 the standard deviation of the first load! Even throwing out that 891, the 5.3 SD is still 2x the 5.4 load.

 

But in the general sense, you want to load 2 or 3 SD's above the required velocity. If your SD is 10 and your bullet is 180 gr, your load should yield 964-974 FPS. Also, be sure to check your bullet weight. There is a tendency to use the cheapest bullets around and you may find some weight variations. Weigh 20 or so bullets and calculate your SD for them and use the nominal weight minus 2 or 3 SDs to calculate your power factor when you chrono your next loads.

 

Later,

Chuck

 

 

I weighed the projectiles and they are coming at 180 gr, 179.9 and 179.8.

 

I also tried a 5.5 grain load and the following were the results

1021

1017

1014

1016

1010

1019

 

the SD is smaller.

 

What about brass - does it also make a difference - all of these test were shot with mix brass of starline, federal, winchester and WIN. 

 

8 hours ago, 3gunDQ said:

 

 

Link to comment
Share on other sites

1 hour ago, jimbullet said:

 

I weighed the projectiles and they are coming at 180 gr, 179.9 and 179.8.

 

I also tried a 5.5 grain load and the following were the results

1021

1017

1014

1016

1010

1019

 

the SD is smaller.

 

What about brass - does it also make a difference - all of these test were shot with mix brass of starline, federal, winchester and WIN. 

 

 

Brass case volume differences can matter. Try to stick to one head stamp to eliminate that for now. The 5.5 load looks very consistent.

Link to comment
Share on other sites

59 minutes ago, tcazes said:

I'm still curious what gun or powder you are using. Haven't mentioned either yet. You havent given any details other thsb charge and velocity... 

STI DVC Limited 40

Win231 powder

 

Edited by jimbullet
Link to comment
Share on other sites

10 minutes ago, ChuckS said:

Brass case volume differences can matter. Try to stick to one head stamp to eliminate that for now. The 5.5 load looks very consistent.

The 5.5 grain load test was also of mix brass though so I am not sure why the high SD still on the lower loads.

 

The 5.5 grain is giving me above 180PF so I dont want to go and use this

 

 

Edited by jimbullet
Link to comment
Share on other sites

Pick out 20 pieces of brass of the same make and try the 5.4 load again.  Also check which is more accurate at 25yds, use a Ransom if you have one or a sturdy bench with whatever rest works best for you and see what you get.  As long as you exceed what ever power factor you are going for then the loads accuracy potential is the most important thing.

Link to comment
Share on other sites

9 minutes ago, Steve RA said:

Pick out 20 pieces of brass of the same make and try the 5.4 load again.  Also check which is more accurate at 25yds, use a Ransom if you have one or a sturdy bench with whatever rest works best for you and see what you get.  As long as you exceed what ever power factor you are going for then the loads accuracy potential is the most important thing.

Thanks Steve,

 

I will try to do a ransom rest test but so far what I have found is this:

 

The 5.5 grain appears accurate as it is consistently hitting steel out at 15 yards (6-7 inch diameter steel) - not a proper gauge but this is what I had so far

 

The 5.3 grain appears to be shooting lower as I had to put a slightly higher point of aim.

 

One thing I just noticed bringing out the caliper is that my OAL is inconsistent! 

 

Measuring 1.159, 1.160, 1.163, 1.167 spreads. - might be a contributor to the variances I am getting?

 

Link to comment
Share on other sites

Several possible reasons for that:

Could be the mixed brass, if the wall thickness varies then the resistance to seating the bullet will also vary, causing some difference in the OAL.

Not knowing what you are using for a press, one possibility is that the shell plate isn't tight enough, allowing some degree of tilt which mixed with the first reason could cause the problem.  Another could be that the diameter of the bullets varies which would have some bearing on the OAL length.

 

I'd guess it's more the first reason which is why you should try the "one brand of brass" test.

Link to comment
Share on other sites

  • 2 weeks later...

more testing - 

Used the same brass brand - Winchester and same brand primer Fiocchi and my raw velocities are as follows:

 

962

1001

962

992

953

938

992

982

988

990

986

960

918

966

 

So far two of the shots would have failed 170PF from what I can see but the average would allow it to pass at PF 174.

 

I cant figure out what could be causing the high deviation from a low 9118 fps to a high of 1001 fps.

 

The two things I can think of  is maybe due to dirty brass? I have used brass which I have reloaded twice already without going to the tumbler. Or it could be the inconsistent OAL. I measured the OAL on all the ammo I used today and OAL is differing from 1.159 to 1.168.

 

Any thoughts, suggestions? 

 

I am thinking it should be adequate to meet the 170PF or should I take that extra safety margin and increase my load by 0.1 grains which will drive this to a 180 PF.

 

 

 

 

 

Link to comment
Share on other sites

jim, there may be a couple of different reasons for the variations.  First, the SDB does not have the most consistent powder measure in the world, and it IS sensitive to press operation.  If the powder doesn't bridge and you operate the press smoothly, there should not be as much variation.

 

Second, it may be improper chrono use.  The most accurate reasing is goint to be along the long axis of the machine and parallel over the windows.  ANY variation WILL affect the reading.  It is amazing how much a little teeny offset can make in the velocity recorded.

Link to comment
Share on other sites

On 7/12/2017 at 9:09 AM, zzt said:

jim, there may be a couple of different reasons for the variations.  First, the SDB does not have the most consistent powder measure in the world, and it IS sensitive to press operation.  If the powder doesn't bridge and you operate the press smoothly, there should not be as much variation.

 

Second, it may be improper chrono use.  The most accurate reasing is goint to be along the long axis of the machine and parallel over the windows.  ANY variation WILL affect the reading.  It is amazing how much a little teeny offset can make in the velocity recorded.

I didnt know that about the SDB.... sensitive in what way - vibration on the bench top - powder not trickling down?

 

I havent thought about the chrono as well, interesting - thanks for this input and I may try to place more accurate shots into it.

 

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...