Data double check New/first Chrono

[DIY-Pete]

So I just got my new chronograph, a Magnetospeed v3, and I was hoping you all would chime in on the story the data tells. I'm new to reloading and still learning.

I was not able to find load data for Berrys bullets with 3n37 so I used the data from VV for a 124 grain Rainier plated bullet and aimed for the middle of the load. (http://www.vihtavuori.com/en/reloading-data/handgun-reloading/9-mm-luger.html)

The load is more accurate than I am and cycles the gun well with no signs of over pressure but the f/s seems a bit slow on the collected data below. Can I bump it up another .1 or .2 gr to better replicate my carry load? Is there something the data is telling me that I am missing?

Thanks
Pete

The details:
Gun used: FNS-9 4" barrel
Mixed brass
5.7 grains of VV 3N37
CCI 500 primer
COL 1.155
124 grain round nose thick plate: Berry's

10 shot data:
Min: 1079
Max 1122
Ave: 1096
S-D: 15.2
ES: 43

Shot- f/s
1- 1122
2- 1104
3- 1087
4- 1082
5- 1114
6- 1079
7- 1111
8- 1090
9- 1084
10- 1088

 

[243winxb]

Can I bump it up another .1 or .2 gr to better replicate my carry load?

Carry load/factory ammo- chasing factory velocity can get you in trouble real fast.

Using mixed brass to load near listed maximum (adding .2 gr) may give mixed results after more loadings. If the primer pockets get enlarged after 3 to 5 loading, the powder charge would need to be reduced.

The current loading seems to be working for you now. Shoot it for a couple loading, see how brass holds up.

A chrono doesnt tell us a lot about pressure.

 

[DIY-Pete]

Thanks 243

Pete

 

[jmr40]

A chrono doesnt tell us a lot about pressure.

It actually tells about as much as most re-loaders need to know. I only load for rifles, so no personal experience with this specific load. But velocity is directly tied to pressure. When your chronograph tells you that you are at the max velocity listed you are at the max pressure. The powder charge may be less than listed in the load data, or it could be more. Technically speaking it would be safe to go over the max charge weight as long as velocity was under the velocity listed at the max charge weight in that firearm. Some guys do this, especially with rifles, but I strongly advise against it. While that load may be safe in one individual firearm it may not be in another.

If you were using the same brand of brass I would say go for it. But with mixed brass probably not. Some of your loads in certain brass will probably be fine , others maybe not.

 

[Blue68f100]

Have you crony your carry load? Published data is just what they got in their test chamber/gun, may or may not be close to what you get in your gun. If I recall Rainer and Berrys use a different core hardness, so there is some differences in velocity between the two. If you have crony your carry and confirmed it's actually slower, you can bump the charge up. But remember that mfg use a canister powder which we can not get. I would not be using mixed brass for these test since case volume plays a big part. I would more likely duplicate the felt recoil than velocity. Look closely for pressure signs as you go up. Another way would be to shorten the length a little increasing the pressure.

 

[DeadEye9]

It actually tells about as much as most re-loaders need to know. I only load for rifles, so no personal experience with this specific load. But velocity is directly tied to pressure. When your chronograph tells you that you are at the max velocity listed you are at the max pressure. The powder charge may be less than listed in the load data, or it could be more. Technically speaking it would be safe to go over the max charge weight as long as velocity was under the velocity listed at the max charge weight in that firearm. Some guys do this, especially with rifles, but I strongly advise against it. While that load may be safe in one individual firearm it may not be in another.

If you were using the same brand of brass I would say go for it. But with mixed brass probably not. Some of your loads in certain brass will probably be fine , others maybe not.

This isn't exactly accurate. While there is a definite correlation between velocity and pressure you really can only guess at pressure using velocity. Just because X manual says 1000 fps happens at 20k PSI and 10gr of Powder Y. Does not mean that if you get 1000fps at 9gr you are also at the same 20k psi. (Fake numbers here) It just doesn't work that way. Even If your charge weight, OAL, case trim length, bullet Type/weight etc are all 100% identical to what a manual states, unless you are shooting said load in the EXACT same firearm or test chamber they used the pressure is going to be different. I'm fortunate enough to have access to transducers at work and have rigged up a method to test actual pressure in a Glock 19 chamber. I can tell you from experience that I've been able to hit the exact same velocity with half a dozen different pressure levels all depending on case type/size/condition, OAL, etc. This was very eye opening for me and taught me first hand that velocity is not a good way to measure pressure. Can you use it to guesstimate, sure and most loaders do, but your never going to know exactly where your pressures are which is why we do ladder loads and such.
Back to the OPs question though, I would set aside a good 50-100 cases of the same headstamp brass, preferably a stamp you have a lot of on hand and plan to use often. Use this ONE headstamp batch to make your ladder loads increasing a tenth or two at a time untill you reach the desired load. Mixed headstamp brass is a practice best saved for loads that have already proven themselves for you and become your regular load, not for developing new loads. As always check for signs of excess pressure and proper function. Personally for me whenever I'm testing max/hot loads in a semi auto I always do the first couple rounds single feed with the magazine removed. This allows for an easy path for pressure to go in the event of an over pressure situation and will usually prevent any damage to the weapon should one of your loads be a little over zealous. Judging from the platform your using, the velocities your getting and your current charge weights, I think you might be better off with a different powder if you want to chase higher velocities. Power Pistol is excellent for top end 9mm loads. I'm able to hit 1260fps with a 124 XTP through a stock Glock 17 with less than a max book load of PP. This is my pet load for weekly action pistol shoots because I also like to train with a load that recoils and has a POI nearly identical to my carry load. (124 HST) I don't think you will be at risk going up to a max book load as long as you don't get shy with your OAL. Do your due diligence with making a ladder, checking for pressure signs etc as mentioned above and you should be good to go. Have fun and be safe.

 

[DIY-Pete]

I rotate my carry ammo out of my gun every three months so the next time I do that I will make sure to run them through the chrono. I carry Horniday critical duty 135gr, standard or +P depending on what is available (standard being my first choice). I got 3n37 because it was on the self so I didn't have to pay shipping or hazmat. I also have 5 lbs of BE-86 on the self as well. As my current load works good I will stick with it for range use and when I chase a max load I will go with new starline brass.

Glad to see that no one found a problem with my current load as tested.

Pete

 

[SCC]

A given load's velocity is dependent on the barrel fired from. Even 2 seemingly identical barrels may produce different velocities with the same ammo. Other than knowing "I'm in the ball park", the best use of the chronograph is to check a load's consistency (ES and SD) and to head off possible pressure issues. For example if 5.1gr of powder produces 1025fps and 5.3gr produces 1050, but 5.5gr produces 1100, then you may be starting to get excessive pressure. That larger jump in velocity is a warning sign. 5.7gr may be risky. It's not perfectly linear, but sudden jumps in velocity should be treated with care.

 

[Walkalong]

Velocity doesn't guarantee pressure. With a change in powder speed it is possible to get the same velocity with different peak pressures. Even less velocity with more pressure.