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Rifles, Reloading, Optics, Equipment
Reloading
Be careful, myths about pressure signs.
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<blockquote data-quote="AJ Peacock" data-source="post: 183135" data-attributes="member: 4885"><p>I did a little experiment over the weekend. I ran a little ladder test with my Savage 300WSM, 200gr Accubond and H4350. I started getting a sticky bolt at 61.5gr and 2820fps. I went on up to 62gr and called it good. I was also getting a pretty good cratering around the firing pin that I felt was due to the poor firing pin fit and the firing pin hole being a little funnelled due to Savage tumbling the bolt heads to remove sharp edges. I wish I had a picture of the bolt face, but here is a picture of 3 brass that was shot at 61.5gr before I made any changes. You can see a well cratered primer and also some shine from the boltface on the picture below.</p><p><img src="http://i168.photobucket.com/albums/u193/AJPeacock_photos/61-5orig.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p></p><p>So I decided to make a few changes and see what kind of changes I could get in the primer/extraction (typical pressure signs that everyone talks about).</p><p></p><p>I took the bolt head over to a friends lathe and faced off .003", which removed the slight dish in the boltface and also squared off the firing pin hole.I re-headspaced the barrel and reran the tests. The cratering looked much better (hole is still oversized, but visually it looks better). The hard extraction was still occurring, so I took the rifle apart and lightly lapped the lugs. I then reinstalled the barrel, headspaced it and put everything back together.</p><p></p><p>Back to the range I went. In the original test, I started getting a sticky bolt lift at 61.5gr of powder. In this final test, I went all the way up to 63gr with absolutely no bolt lift pressure and a much better looking primer, as can be seen in this picture at 63gr's. No marks were picked up from the boltface at this loading with the 'cleaned up' boltface. The few marks that can be seen are from previous loadings of this same brass.</p><p></p><p><img src="http://i168.photobucket.com/albums/u193/AJPeacock_photos/63faced-lapped.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>So, be careful when looking at these 'pressure' signs, as they are relative to everything that is happening on your rifle and shouldn't be taken as absolutes. In neither of the pictures above do you see a flattened primer that no longer has the rounded edges, but that sign can also be misleading, as different primers and even different lots of the same primer can be made from metal that is harder or softer.</p><p></p><p>AJ</p></blockquote><p></p>
[QUOTE="AJ Peacock, post: 183135, member: 4885"] I did a little experiment over the weekend. I ran a little ladder test with my Savage 300WSM, 200gr Accubond and H4350. I started getting a sticky bolt at 61.5gr and 2820fps. I went on up to 62gr and called it good. I was also getting a pretty good cratering around the firing pin that I felt was due to the poor firing pin fit and the firing pin hole being a little funnelled due to Savage tumbling the bolt heads to remove sharp edges. I wish I had a picture of the bolt face, but here is a picture of 3 brass that was shot at 61.5gr before I made any changes. You can see a well cratered primer and also some shine from the boltface on the picture below. [IMG]http://i168.photobucket.com/albums/u193/AJPeacock_photos/61-5orig.jpg[/IMG] So I decided to make a few changes and see what kind of changes I could get in the primer/extraction (typical pressure signs that everyone talks about). I took the bolt head over to a friends lathe and faced off .003", which removed the slight dish in the boltface and also squared off the firing pin hole.I re-headspaced the barrel and reran the tests. The cratering looked much better (hole is still oversized, but visually it looks better). The hard extraction was still occurring, so I took the rifle apart and lightly lapped the lugs. I then reinstalled the barrel, headspaced it and put everything back together. Back to the range I went. In the original test, I started getting a sticky bolt lift at 61.5gr of powder. In this final test, I went all the way up to 63gr with absolutely no bolt lift pressure and a much better looking primer, as can be seen in this picture at 63gr's. No marks were picked up from the boltface at this loading with the 'cleaned up' boltface. The few marks that can be seen are from previous loadings of this same brass. [IMG]http://i168.photobucket.com/albums/u193/AJPeacock_photos/63faced-lapped.jpg[/IMG] So, be careful when looking at these 'pressure' signs, as they are relative to everything that is happening on your rifle and shouldn't be taken as absolutes. In neither of the pictures above do you see a flattened primer that no longer has the rounded edges, but that sign can also be misleading, as different primers and even different lots of the same primer can be made from metal that is harder or softer. AJ [/QUOTE]
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Be careful, myths about pressure signs.
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