Help! I've lost 500fps!

[Mr Fudd]

1" higher would make sense with a lower velocity load if he was measuring the maximum ordinate.

In other words if he zeroed at 200 yards he would then expect something like 1" high at 100 yards. If he found that it was in fact 2" high at 100 yards on shooting the lower velocity is indicated.

weird one, losing 500fps seems almost impossible without maybe having used a much slower powder in the second set of loads.

Soot on the cases?

Flashheart you are exactly right, first batch chrono avg 3550fps zeroed at 200 yards, 1" high peak at 130 yards, yet with the new batch chrono avg 3060fps! and its 2" high at 125 yards!!??

Going to clean the barrel and then I'm starting my powder loads again as something is definitely a miss!

[Randy Bohannon]

There's also the simple fact that lower velocity rounds exit later in the recoil cycle. Certainly in pistol shooting, high strikes are generally a sign of reduced velocity.

low velocity pistol rounds sure, the OP mentioned the maximum ordinate in his OP in reference to a high velocity rifle however.

[Randy Bohannon]

Flashheart you are exactly right, first batch chrono avg 3550fps zeroed at 200 yards, 1" high peak at 130 yards, yet with the new batch chrono avg 3060fps! and its 2" high at 125 yards!!??

Going to clean the barrel and then I'm starting my powder loads again as something is definitely a miss!

Check you used the same powder from both mate, if it wasn't for the difference in the trajectory I would have said it was the chrono.

[MikB]

low velocity pistol rounds sure, the OP mentioned the maximum ordinate in his OP in reference to a high velocity rifle however.

Nevertheless, the centre of shoulder resistance is still below the centreline of the bore, so an upward couple will result on the muzzle in recoil. Principle is the same, though the effect is (much) more marked in pistols.

Fudd, I'm guessing you rezeroed the suspect load at 200 to find the 2" peak at 125? If you did, I suspect it was because you found it low at 200 at compared to the first batch zero?

[Randy Bohannon]

Nevertheless, the centre of shoulder resistance is still below the centreline of the bore, so an upward couple will result on the muzzle in recoil. Principle is the same, though the effect is (much) more marked in pistols.

Fudd, I'm guessing you rezeroed the suspect load at 200 to find the 2" peak at 125? If you did, I suspect it was because you found it low at 200 at compared to the first batch zero?

Indeed but I have never seen a rifle that shot lower with a faster load than with a slower, have you?

Were it not for the zero confirmation of the lower velocity I would have suspected that he had fallen foul of the chrony not be fully folded out for the first batch.

He must have rezeroed to get the higher maximum ordinate.

[MikB]

Indeed but I have never seen a rifle that shot lower with a faster load than with a slower, have you?

Not sure. It was a while ago, but I think I got a high MPI with some .303 pussycat loads I was trying.

[Mr Fudd]

Yes first batch zeroed at 200, with the second batch I started doing my range card at 50 yards so didn't really notice the difference as put it down to me however by the time I'd got back to 100 yards I knew there was a rabbit off so went back to 200 and it was about an 1"-1.5" low!?

However I finally got back out last night with a clean barrel and new scope mounts as also think that they might have been a factor, however after redoing my powder weights I can't get them up to 3550fps!?

36gr in the hornady book should be putting out over 3700fps yet I'm only getting 3400fps I can only assume that in making my notes I've somehow accidentally used the velocity from the factory rounds I originally started with??

It is only a 20" barrel so may account for some of the loss but surely not 300fps!? Or is it a case of them being a little adventurous with the figures?

So this leads me on to a new question, can I go over the max load stated in the book as if I'm not getting the max velocity then I'm not creating the max pressure?

[bullbarrel]

If its a slower powder than 20" might make a difference. I've seen 50fps per inch quoted before, so if test was 26" then potential for 300fps loss.

[activeviii]

you said new gun. barrel bedding in maybe?

[camerafodder]

Y

So this leads me on to a new question, can I go over the max load stated in the book as if I'm not getting the max velocity then I'm not creating the max pressure?

Don't do this. The max chamber pressure is achieved when the bullet has barely moved. This is down to the relationship between burn rate and available volume behind the bullet. Faster powders may yield better results from short barrels but that early pressure figure is the key figure. Don't go beyond the book figures.

[kennyc]

It is only a 20" barrel so may account for some of the loss but surely not 300fps!? Or is it a case of them being a little adventurous with the figures?

So this leads me on to a new question, can I go over the max load stated in the book as if I'm not getting the max velocity then I'm not creating the max pressure?

they are almost always optomistic with speeds, and yes you can go over book max charges HOWEVER you need to know what you are doing! the fact you felt the need to ask the question suggests you need to do a lot of research into the subject first.
read this inwardly digest and UNDERSTAND and then then start reading some books on reloading practises.

[Mr Fudd]

Thanks for the info and not planning on exceeding the book max just made sense to me logically however not that advanced in reloading as only making up my hunting rounds

Will also have a look at other heads and loads for something a bit faster

[pothunter]

Thanks for the info and not planning on exceeding the book max just made sense to me logically however not that advanced in reloading as only making up my hunting rounds

Will also have a look at other heads and loads for something a bit faster

The need for speed isn't always the answer, accuracy and consistency that exceeds factory loads tends to be my goal when reloading.