Question........I recently shot some 300 H&H loads that I had loaded. Loads were on the VERY mild side....180's going about 2750. I crimped them using the crimp in the seater die (RCBS). I am using Winchester Mag primers. Here's the deal.....With this mild load, the primers are filling the primer pocket and are pretty much flat. There are no extractor marks or anyhting else to indicate high pressure though.The slightly rounded outer edge of the primer cup is still barely visible. Are WM primers soft? Is the crimp elevating pressure? This load is 5 grains below max with H4831 according to Nosler, as I am just shooting the gun to get used to it. What, if anything in this equation should I be concerned about? I eventually want to boost this load to near max if it groups well. If and when I do this, should I eliminate the crimp to avoid boosting pressure unnecessarily? Thanks for your thoughts,
Wyo

The crimp will not boost pressures to any real measurable degree. The crimp does, however, often even the pressures out by making bullet pull more consistent. Is there any chance your cases are too long? If the case length is too long and the mouth of the case is being forced into the bullet lead area, and a heavy crimp will often allow this to happen unnoticed, then there is no room for the case mouth and neck to expand and release the bullet. That will rocket pressures regardless of the load. IIRC Winchester primers are quite hard so I doubt it is from soft cups like you often see with Federal primers. Indeed your load sounds as if it is on the light side, so here are a couple of thoughts. With light loads, sometimes the primer will back out of the primer pocket on shooting. The case then sets back against the bolt face when the pressure builds and causes the primer to rivet. I have a hunch that this is what is happening. Other signs of this happening is very sooty case bodies where the case has not expanded to seal the chamber correctly. Also, if you are not already doing so, you might try setting your sizing die so that you are only setting the shoulder back just a hair, sort of doing a neck size with the FL sizer. With the shallow shoulder of the H&H this is not as easy to do as with a Winny or a Weatherby, but you can still do it. A die that is setting the shoulder back too far, and then if the chamber was cut on the long side, there may be a slight headspace problem with using the belt as the sole control for headspace. If the headspace is off even a few thousandths of an inch, the riveting primer can show up also.
As you work up the load and increase the charge, pay close attention to all pressure signs, and if you increase the charge a grain or two and suddenly the primers start to appear normal, then riveting is what caused them to flatten. Most likely from the load being too low in pressure as stated above.

[ 11-22-2003, 05:51: Message edited by: Big Bore ]

Wyocowboyshooter,

Since the 300H&H is a bottleneck cartridge there is no need to crimp.. Crimping will infact build more pressure. I would try it without the crimp and see what happens.

6.5 Bandit

WyoCS, 86 the crimp! The .300 H&H has a generous case neck, and I see no need for a crimp. 180's are a great choice in 30 calibre with good S/D and reasonable length.

Also, this case, coupled with the .30 calibre bore, has the capacity to launch them at a rapid clip w/o pressure spikes. The 4350's and 4831's are to my knowledge, among the best powder choices for this cartridge if history has anything to say about it.

Regarding primers, I think the W-W primers are soft, as well as undersized in general. I have thrown brass out before its time because of those primers, blaming stretched pockets and top end loads, instead of the primer. I've experienced undersized primers in the R-P line some years back too. IMHO, stick with Federals and CCI's.

Personaly I'd suspect a headspace issue (not saying it's any worse than a lot of belted chambers BTW).
The brass is fully forward when the primer ignites, the rise in pressure first causes the neck to expand sealing/gripping the chamber neck area, the bullet starts to move forward. Second the primer moves back to the bolt face and the body starts to grip the chamber wall. Finaly the case head moves back to meet the bolt face. You will notice that there is a time when the primer can be unsupported (over part of it's length) by the primer pocket.
Sizing the shoulder back just enough to rechamber the brass easily (there-by headspacing on the shoulder) should eliminate the primer "signs" your seeing.

Thanks for the ideas guys.........here are a few specifics on the load:

NEW W-W cases
Win Mag Primers
65 gr H4831
180 grain Hornady Interlock

Cases were new, and most of them were below trim-to length, so I trimmed them all to a common length, that being 2.820". I know this is kinda short, but I have no reason to believe that this could have adverse effects. Any other thoughts? Thanks agin for the comments!

Here is my thought,,,,

Possible, this may be happening.

New brass, mild load.

Firing pin bumps brass forward, ignites powder, primer moves back, brass moves back, Flattens primers...'

Check fired case fit in chamber, try not to move shoulder back when sizing, reload, re-evaluate..

To much fun....

I don't put a lot of stock in primer appearance as a pressure indicator, with the exception of primers being loose or falling out. When working up loads in 1 grain steps, I often can't tell one primer from the other, even when the top load to the starting load may be 5-6 grains difference. Any change in brands makes the comparison impossible.

My vote goes to excessive head space. Not that there is anything wrong with your rifle, rather the new brass may be on the small side. Try the load with once fired, Partial F-length sized brass and let us know what happens.

Turok

I was wondering about the use of a magnum primer. I checked Speer #7, #8, #10 and #13 and didn't find a single H4831 180 gr .300 H&H load using a magnum primer. Granted, it isn't a lot hotter than a standard primer, but it is hotter. Speer #7 p. 66 says a CCI 200 has 9.20 ft-lbs of energy while a CCI 250 has 9.45 ft-lbs of energy. One of the reasons to reduce the starting load by 10% is a change in primers and 10% would be 63 gr, not 65 gr, since the max load for 35 years has been 70 gr of H4831.

Methinks Turok has the right idea. Neck size or partial FL size, same load. sundog

Thanks gentlemen, I'll do just that and get back to you.

I make my .300 H&H brass from .375 H&H cases. That way I can set the headspace to the shoulder with the first shot. That 8 degree shoulder does not hold all that well even then but it's better than nothing.

All of the belted chambers that I have checked were over spec in headspace by .001". Not only that but the brass is under the minimum dimension. See a post by John Ricks for this information here.

You can make a "headspace gage" by soft soldering a tiny spot of solder on the belt and filing it just right so it crush fits in your chamber. The headspace tolerance is .220"-.227"

Also make a feeler wire to check for insipiant head separations. You can feel them from the inside but not see them on the outside until it's too late.