I was doing a ladder test on my 6.5-284 using Reloader 22 with 130 gr Swift Scirocco loaded to an COAL of 2.88" Starting charge was 51g working up to max charge of 53.5g. I was seeing a thin shiny line on the base of the cartridge case on most if not all powder charges. I never experienced any stiff bolt lift on any of the charges. I am attaching a photo of my Max load cases and if you look at the bottom case in the photo you can see the mark starting at the "E" in SUPER and extending over to the "N" in WINCHESTER. What is this mark and what is it telling me ? The action on the rifle is a SAKO L579
Reloading Pressure question
- Thread starter gdc2
- Start date
jepp2
Gold $$ Contributor
Kind of tough to tell from your picture. Can you get a better close up in higher resolution? Were there any brass particles on the bolt face? Were you using a chronograph? What was the measure velocity vs the predicted?
jepp2 Thanks for the response, I didnt notice any brass particles but figure it may be from the extractor passing over the case head when the bolt is rotated ? My chronograph (Pro-Chrono) has been super reliable over the years but was not working properly on this day only giving a few readings. One reading I got was 2890fps at 53g which is .5 grains lower charge that the case in the photo, that's why I was feeling a little uneasy not having accurate reads from the crono to further reassure me I was still in a good zone. Attached is a better photo
AINyhus, I just noticed your post, and thats what Im thinking as well.
Thank you
AINyhus, I just noticed your post, and thats what Im thinking as well.
Thank you
Attachments
Just to reinforce what others have said, the best indicators I've found of high pressure is hard bolt lift and an extractor depression / mark on the case head.
While flattened primers can also be an indication of high pressure, normally if you have a high-pressure situation, you will also have the aforementioned indications so flattened primers alone is not normally a conclusive indicator of high pressure.
The only time I experienced a significant high-pressure situation was with H380 (ball powder) in a 22 250 and this occurred in the field during a 90 degree+ day hunting ground hogs. In that case, I had all three of the above indicators. Interesting, the load was a well-established load in the manuals and performed without incident at the range under cover.
While flattened primers can also be an indication of high pressure, normally if you have a high-pressure situation, you will also have the aforementioned indications so flattened primers alone is not normally a conclusive indicator of high pressure.
The only time I experienced a significant high-pressure situation was with H380 (ball powder) in a 22 250 and this occurred in the field during a 90 degree+ day hunting ground hogs. In that case, I had all three of the above indicators. Interesting, the load was a well-established load in the manuals and performed without incident at the range under cover.
That looks juicy to me. Primer is flat in the image but not cratered. If it was a nice hot day when shot and the round was exposed to the heat it should be OK.
If it was a cold day I'd test as warmer weather approaches.
Im in New England and it was about a 65-70 degree day, the loads will be used deer hunting in Maine where the average temp will be about 30-40 degrees. No hot weather use planned. As far as a max charge 53.5 is as far as Im going and now will work on seating depth. Nosler reloading data shows 54g Max, this is however with a longer COAL of 2.98" I am ranging between 2.89"-2.865" while testing seating depth
The Nosler data and your primer indicate that you're certainly getting there in terms pressure. CIP lists a tad over 59,000 PSI as max for the 6.5 x 284 Norma. My non-varmint hunting loads are crimped into the cannlure if the bullets have it. If not maybe you can experiment with the seating to improve accuracy. That may change pressure for you.
Yes, even though I have not experienced stiff bolt lift I do believe I'm approaching or at Max. My COAL is reduced from the Nosler data however I believe my Winchester cases have greater capacity than the Nosler brass which should possibly offset the COAL difference a small amount
Back in the day I made a serious reloading mistake that ended up with the primer falling out of the case when the bolt was opened, due to the heavy FP spring, heavy FP and excellent tip shape and hole fit, there was absolutely no crater. On the other hand Remingtons that I have owned cratered primers regularly with loads that showed no other signs of extreme pressure. Looking at the edges of your primers I would stop right where you are. If you happen to shoot that load in warmer weather you may see more pressure than you like. On the bright mark, I would chalk that up to a small burr.
Perhaps a poor choice of words, an impression of the extractor on the case head from being forced under excessive pressure against the bolt.
You said it yourself - max loads. The streak can only be caused by a high point on the bolt face being dragged across the case head when rotating the bolt. My guess is that you are just a little below pressures that would give hard bolt lift ejector swipe marks.
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