Help! I've lost 500fps!

[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.