Rich in VA

What primer were you using? I ask because Rem BR primers have a little thicker cup than most [if not all] of the others and thus do not show pressure as readily, but that does not mean you are not getting pressure. In my experience with the Mach IV the velocities you are getting indicate a
hot, hot, hot, hot load. Get my drift! But you say the bolt handle is not sticking. I always look for heavy bolt lift as the first warning sign---yet you don't have it and your load is way too fast for that cartridge. Don't know what to say!!

Jordan

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Originally posted by Jordan:
In my experience with the Mach IV the velocities you are getting indicate a
hot, hot, hot, hot load. --- I always look for heavy bolt lift as the first warning sign---yet you don't have it and your load is way too fast for that cartridge. Don't know what to say!

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I know what to say: That load is HOT. There are no free lunches and no black magic involved in handloading, if you get more velocity than other fellows you are using more pressure. It's as simple as that.

Flat primers, case web expansion, ejector hole marks and the like are good indicators of excess headspace. As far as web expansion goes, it can also be a result of large tolerances between chamber and case. They rarely have any relation to actual pressure.

The layman's best method of estamating pressure; short of a Fabrique Scientific or Ohler strain gauge; is a chronograph. If you are getting the same velocities as the book loads in as long a bbl and with the same reloading components, you are operating at quite similar pressure - no matter if you're a bit off (normally higher) in load weight. If Nosler or whoever managed to reach 3300 fps @ 65,000 psi and you are getting 3450 fps, you can bet you cute lil' pink behind that you're operating at more than 65,000 psi.

There is no, repeat no, way to get more force with the same pressure. That would be like changing a dollar into twelve dimes, it doesn't add up...

-- Mats

Again, no sticky bolt lift, no marks on the brass. Like you, I am sorta puzzled.

Rich

quote:

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Originally posted by Jordan:
Crow:

What primer were you using? I ask because Rem BR primers have a little thicker cup than most [if not all] of the others and thus do not show pressure as readily, but that does not mean you are not getting pressure. In my experience with the Mach IV the velocities you are getting indicate a
hot, hot, hot, hot load. Get my drift! But you say the bolt handle is not sticking. I always look for heavy bolt lift as the first warning sign---yet you don't have it and your load is way too fast for that cartridge. Don't know what to say!!

Jordan

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I firelapped one of my m96 swedish mausers and it immediately started clocking 100 - 120 FPS faster than before lapping. It is generating the same pressures it always did, but sending the bullet downrange more efficiently. I suspect hog wallows and tight spots in a barrel impedes the work being done more than we think. After this, I began to realize using a chronograph to develop loads can be iffy and potentially dangerous as well.

Ken Howell had a thread in Shooters a few months back, where he addressed this very phenomina. Ken told of a certain wildcat that had hard brass and thicker walls and bases that would not show classic pressure signs until it was well over 70 kPSI.

My instinct tells me your load is pretty hot. If it were me, I would try different brass and primers and work the load up again looking for any pressure signs along the way.

Scott

Todd Kindler-Editor Small Caliber News www.smallcaliber.com (330)897-0614

No problem on butting in, I posted the note for info. I do find it a bit hard to agree with your figures. I think you must have input something incorrectly, as 18 grs of H4198 will go into a Mach IV case easily.

Regardless, I plan to tone down the loads a bit before resuming testing....... I think 3900 with this bullet is plenty. No sense in tempting the fates......

Thanks for your post.

Rich