Pressure /Velocity Question

[Dunk]

I do not have a chrony. If you have two rifles of the same caliber with the same barrel length and one rifles max load is 4gr less with the same powder what should you expect for velocity comparability?




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[horseman2]

There are too many variables but more powder generally equates to increased velocity.
Variables which you have failed to disclose start with Make, Model, Calibre, barrel length, bullet, case, primer, powder and the overall length of two rounds seated to the lands.
The closest comparison would be the .30-06 and the .30-06 AI. 4 grains of powder gave about 100 fps increase.
In short . . . there is no way of really knowing short of using a chrono and pressure signs might not indicate how close you are to a spike.

 

[Dogleg]

Your best bet is to get a chronograph, trying to predict velocity is an iffy thing and reading pressure signs isn't an exact science.

I've had tight chambered, quality barrelled rifles that make max book speed with the starting loads. Then there's plenty of rifles that come up a couple hundred short with the snot loaded out of them. Then there's the rifles that don't show much for pressure signs until the bolt gets sticky. How about the loose chambered factory rifles that show wildly flattened primers with factory loads? Load that same rifle with neck-sized cases and all of a sudden the primers look good.

 

[joe-nwt]

I do not have a chrony. If you have two rifles of the same caliber with the same barrel length and one rifles max load is 4gr less with the same powder what should you expect for velocity comparability?





?

Just the fact that one barrel shows max at 4grs less than the other shows how different two barrels can be. Max pressure in one barrel does NOT necessarily equate to the same velocity at max pressure in another. As stated, typically more powder = more velocity.

You can get a chrony for $100.00 and change.

 

[H4831]

I do not have a chrony. If you have two rifles of the same caliber with the same barrel length and one rifles max load is 4gr less with the same powder what should you expect for velocity comparability?

One apparently identical rifle standing 4 grains more powder than the other, is quite a spread.
I have had two similar cases, but in both pairs of rifles, it was closer to 2 grains difference.
To your question, with each rifle maxed out, I will predict that the rifle that takes the most powder to max out, will have the highest velocity, by probably as much as 75 to 100 fps.
This has been my experience, plus I have read this in international gun magazines.

 

[Dunk]

Thank you H4831. This is the kind of info I was looking for. All responses appreciated.

 

[stubblejumper]

Without a chronograph, you are only guessing.I have seen over 100fps difference just by changing powder lots. I have also seen over 100fps difference between two different barrels,both using the max load of identical components, with each rifle.