14 replies to this topic

[Canuck63]

Hi all,
yesterday I've given a handful of cartridges (200 grainers SWCBB over 4.6grs og N310 for a PF of 176)to a bud to give this load a try and today he's called me on the phone asking if they were cartridges for minor,since they barely reached a PF of 150 .I told him that A)I shoot major and that B ) they came from a box of cartridges that had been chronoed during a match,hitting a 176 PF and that his chrono's battery may have given up the ghost.At his point he did reply that in fact even his very own cartridges which up to last training session gave a PF of 174 barely reached 130 with a tremendous spread between cartridges !
Now,since he's assured me that his chrono's ok and so is its battery which could be the cause of such a tremendous loss in velocity and resulting PF drop (or the other way round)?
I told him to check the barrel for any hairline cracks around the chamber area or even along the whole barrel because if the pistol performed flawlessly up until Tuesday I cannot think of any other reason.He hasn't checjked the gun for accuracy,just chronoed them rounds,packed up his thing and started scratching his head.
I'd really love to hear from you and tell my friend about your thoughts!
TIA
Manny

Edited by Canuck63, 15 March 2012 - 08:09 AM.

[Rob Tompkins]

First you have to try a different chrono or even two (better) in line with each other before you can KNOW its a gun problem.

If it is gun problem, I have no clue.

[Canuck63]

First you have to try a different chrono or even two (better) in line with each other before you can KNOW its a gun problem.

If it is gun problem, I have no clue.

Hi Rob,
for starters thanks a lot for chimin' in.That's exactly what I've told my friend a few minutes ago when he's called me again.Now I'm curious to know the readings from a different chriono,but in case it'll work fine the hairline crack is the only thing I can think of!

Manny

[Rob Tompkins]

First you have to try a different chrono or even two (better) in line with each other before you can KNOW its a gun problem.

If it is gun problem, I have no clue.

Hi Rob,
for starters thanks a lot for chimin' in.That's exactly what I've told my friend a few minutes ago when he's called me again.Now I'm curious to know the readings from a different chriono,but in case it'll work fine the hairline crack is the only thing I can think of!

Manny

A gas leak like a crack could do it but there would be all kinds of gunk inside the gun, right?

[Canuck63]

First you have to try a different chrono or even two (better) in line with each other before you can KNOW its a gun problem.

If it is gun problem, I have no clue.

Hi Rob,
for starters thanks a lot for chimin' in.That's exactly what I've told my friend a few minutes ago when he's called me again.Now I'm curious to know the readings from a different chriono,but in case it'll work fine the hairline crack is the only thing I can think of!

Manny

A gas leak like a crack could do it but there would be all kinds of gunk inside the gun, right?

Absolutely!Further...the high pressure would be felt,at least on the hands!

Edited by Canuck63, 15 March 2012 - 09:08 AM.

[Merlin Orr]

I think I would chunk the rest of the cartridges in the trash and go from there with the gun with a know baseline load other than this one.....

[Canuck63]

I think I would chunk the rest of the cartridges in the trash and go from there with the gun with a know baseline load other than this one.....

Hi Merlin,
as I've written in my first post the cartridges he's chronoed came from my box of match loads and I'm anal as I can be when it comes to being on the safe side with PFs!Davide has chronoed his own loads before last Saturday's match and I think he knows a thing or two about reloading since he's one of the guys of the Modified Italian Team who won the gold at the IPSC European Championship in Serbia last year and the bronze at Bali.
If he was a noob then anything would make sense but since he's one of the Tanfoglio "factory" shooters I think he's done all that he could to make sure that the chrono(s)b was/were working...he hadn't the gun with him when he called me therefore a quick check was out of the question but since he was as puzzled as I am about this strange thing I thought I'd have asked here!
My gun's barrel may be different but IMHO a difference of more than 20 points isn't justified!
Assuming that two chronos put "in battery" would give just about the same readings,which I'm reasonably sure will be similar to the last ones,what could cause such a drop of velocity then?The bullets are ok...the powder throws are constant,the bore hasn't turned into a 50AE...

Edited by Canuck63, 15 March 2012 - 09:38 AM.

[lawboy]

I think I would chunk the rest of the cartridges in the trash and go from there with the gun with a know baseline load other than this one.....

Hi Merlin,
as I've written in my first post the cartridges he's chronoed came from my box of match loads and I'm anal as I can be when it comes to being on the safe side with PFs!Davide has chronoed his own loads before last Saturday's match and I think he knows a thing or two about reloading since he's one of the guys of the Modified Italian Team who won the gold at the IPSC European Championship in Serbia last year and the bronze at Bali.
If he was a noob then anything would make sense but since he's one of the Tanfoglio "factory" shooters I think he's done all that he could to make sure that the chrono(s)b was/were working...he hadn't the gun with him when he called me therefore a quick check was out of the question but since he was as puzzled as I am about this strange thing I thought I'd have asked here!
My gun's barrel may be different but IMHO a difference of more than 20 points isn't justified!
Assuming that two chronos put "in battery" would give just about the same readings,which I'm reasonably sure will be similar to the last ones,what could cause such a drop of velocity then?The bullets are ok...the powder throws are constant,the bore hasn't turned into a 50AE...

What kind of chrono is he using, what kind of skyscreens are on it, what were the lighting conditions when he chronoed the loads?

[CocoBolo]

If your vision is bad 130 and 180 look almost the same. My best guess is Chrono, and it could be fine it could be lighting conditions or placement. I think if there was a barrel crack the guy would have what us open guys call super face.

[Hi-Power Jack]

My best guess is Chrono, if there was a barrel crack the guy would have super face.

+1. Best guess is the chrono.

[HRider]

What were the weather conditions? Is N310 temp sensitive?
Hurley

[Boss1622]

I'm sure you already know this but make sure he is tilting the gun to get the powder in the back of the case before testing. With 4.6 grs in a .45 case you have a lot of air and this can change the FPS a ton.

[Merlin Orr]

Any resolution on the differences in the velocities...?

[Canuck63]

Hi all,
I finally got in touch with Davide and he's told me that he's found the culprit....no hairline cracks in the barrel (I love that super-face thing though ) ...no faulty chronos (he used three or four)...he just got a cr@ppy batch of Fiocchi LP primers!
He dumped them and loaded with what he regularly uses (CCI for training and Federals for matches) and everything went as smooth as silk!These Fiocchis are 24karat cr@p but he's been given them for trials and couldn't imagine that they'd have behaved this way!
Hurley...I'm with you on the N310 being temperature (and height above sea level ) sensitive...ask me how I know!!!!
Boss...I know that trick,even if I don't tilt the gun,I'd rather let the rounds rest on their head for a few days...thank you very much for the tip anyway!

Manny

[Canuck63]

Yet.....the differences between the readings when he tested my ammo are definitely to be put down to a faulty chrono!

Manny