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Magnum primers or standard

I have a problem which I think is related to the primer used. 7SAUM using VV N165, 61.2gns with 190gn A- tips CCIBR2 primer, speed is only 2840fps, after firing 3-4 rounds in testing I cannot chamber another round. This has happened twice now as the first time I thought it was a brass sizing issue. Looking down the barrel I see what appears to be a lot of either unburnt powder or residue. I'm assuming this is why I can't chamber a round after 4 shots. I tested with jump and couldn't find anything that looked good on paper so went to jam. So now I have this problem. Is it because I should be using CCI 250's.
 
And tell us the exact load. When you jam, the pressure can be higher by several KPSI so if you were loading toward the top and jamming, you may have tipped over.

Take a hard look at the brass.
Does the case head show the extractor imprint?
Is the primer radius round or showing signs of flattening out?
Will that fired brass re-chamber and allow you to close the bolt with ease?

If there are no signs of pressure, then try dry swabbing the chamber on the next test runs and see if it is in fact just a polluted chamber.

ETA and yes, I would try a magnum primer with a SAUM.
 
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I have a problem which I think is related to the primer used. 7SAUM using VV N165, 61.2gns with 190gn A- tips CCIBR2 primer, speed is only 2840fps, after firing 3-4 rounds in testing I cannot chamber another round. This has happened twice now as the first time I thought it was a brass sizing issue. Looking down the barrel I see what appears to be a lot of either unburnt powder or residue. I'm assuming this is why I can't chamber a round after 4 shots. I tested with jump and couldn't find anything that looked good on paper so went to jam. So now I have this problem. Is it because I should be using CCI 250's.
Using that much of VV-N165 with a heavy bullet for caliber I would use a magnum primer. Good idea to back off the load at least 1 grain and could back down even more and start over with your development. With magnum cases I would start off the lands somewhat and work back into them as well. I would also check the throat/neck area of the chamber for carbon build-up.
 
And tell us the exact load. When you jam, the pressure can be higher by several KPSI so if you were loading toward the top and jamming, you may have tipped over.

Take a hard look at the brass.
Does the case head show the extractor imprint?
Is the primer radius round or showing signs of flattening out?
Will that fired brass re-chamber and allow you to close the bolt with ease?

If there are no signs of pressure, then try dry swabbing the chamber on the next test runs and see if it is in fact just a polluted chamber.

ETA and yes, I would try a magnum primer with a SAUM.
Exact load, as above, 61.4gns no signs of pressure, no extractor marks. A fired case fits without issue.
No unburnt powder just what I would call lots of burnt powder residue.
But looking with the borescope before cleaning, the lead has a lot of copper for 4 shots fired, lots of copper on one lan. Cleaned then tried a dummy round to the same OAL and it fitted without issue. This is a newish barrel with less than 100 rounds on it. The copper appears to have been stopping the round to chamber.??
 
I have a problem which I think is related to the primer used. 7SAUM using VV N165, 61.2gns with 190gn A- tips CCIBR2 primer, speed is only 2840fps, after firing 3-4 rounds in testing I cannot chamber another round. This has happened twice now as the first time I thought it was a brass sizing issue. Looking down the barrel I see what appears to be a lot of either unburnt powder or residue. I'm assuming this is why I can't chamber a round after 4 shots. I tested with jump and couldn't find anything that looked good on paper so went to jam. So now I have this problem. Is it because I should be using CCI 250's.
I run N165 in 7 saum with standard large rifle.
I prefer N165 for 180 and lighter.


That charge seems awfully spicy especially with 190’s.
 
The copper appears to have been stopping the round to chamber.??
Not impossible, but do double check your seating depths and double inspect everything else.
If you load close to the lands, it is rare but it can happen, especially with a freshly cut barrel.

Say for example, the lands have some sharp smeared edges and the new owner is trying to find the distance to the lands with a few of their favorite bullets, but without lapping and before break in. It may be possible if they were not watching close, to get an above average amount of copper scraped off those test pieces which might raise pressure just like a jam load or cause difficult loading.

It takes a good bit of interference between either the case or the bullet to give you the perception of not being able to chamber a round, but let's face it, we are talking paper thin dimensions that tip things over. It is just that as loaders, we are supposed to keep things clear unless we are intentionally jamming. If it doesn't feel right closing the bolt, I would stop and figure it out.

If the brass goes in and out easily as sized and ready for loading, and also after firing, then see if your seating depth is under control. Nothing wrong with a good scrub of that barrel and an abundance of caution when you proceed. Don't pull the trigger if the little voice in your head says otherwise, get some experienced help in that case.
 

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