Cratering on .223 Rem primers question.

[wang243]

Looking for better accuracy out of my Savage LRPV I recently change powders from VVN140 to the Sierra's recommended accuracy load powder VVN540 and noted cratering on the most of the primers. The extent of the cratering was the same on all the primers regardless of the charge all the way to near max load with no other pressure signs noted on the brass.

Everything about the load was the same (Sierra bullet, CCI450 primer, Lapaua brass, jump)except the powder charges.

My question is: Is the cratering caused by the faster burning N540 powder causing a pressure spike even at a 1 grain charge below Sierra's max load numbers or do I have another problem I should be looking for.


Thanks for any and all thoughts!

W

 

[Wirelessguy2005]

If all you switched was the powder and now you are experiencing primer catering I think you have your answer.

Don't ever trust what they write in the loading manuals, those are for general guidance only. Most likely many of the parts they were using on their test gun and ammo were very different than what you are working with. If the brass alone has a little different internal volume using the book loads could be problematic.

 

[ASbobcat]

Looking for better accuracy out of my Savage LRPV I recently change powders from VVN140 to the Sierra's recommended accuracy load powder VVN540 and noted cratering on the most of the primers. The extent of the cratering was the same on all the primers regardless of the charge all the way to near max load with no other pressure signs noted on the brass.

Everything about the load was the same (Sierra bullet, CCI450 primer, Lapaua brass, jump)except the powder charges.

My question is: Is the cratering caused by the faster burning N540 powder causing a pressure spike even at a 1 grain charge below Sierra's max load numbers or do I have another problem I should be looking for.


Thanks for any and all thoughts!

W

N540 is a higher energy propellant due to it's higher NG content, and as such it is more sensitive to pressure spikes when approaching max loads. Having said that, most of the 500 series burn most efficiently near max pressure.
Primer cratering by itself is not necessarily an indication of excess pressure, especially in Savages which tend to have oversize firing pin holes (I own several and have replaced most of the bolt heads with PT&G).
More reliable indicators are stiff bolt lift, primer pocket spreading and/or sudden jumps in MV.

 

[wang243]

N540 is a higher energy propellant due to it's higher NG content, and as such it is more sensitive to pressure spikes when approaching max loads. Having said that, most of the 500 series burn most efficiently near max pressure.
Primer cratering by itself is not necessarily an indication of excess pressure, especially in Savages which tend to have oversize firing pin holes (I own several and have replaced most of the bolt heads with PT&G).
More reliable indicators are stiff bolt lift, primer pocket spreading and/or sudden jumps in MV.

I would love to think it was the firing pin but I have used max loads of RL15, LT32, H322 and N140 and this is the first time I have noted cratering.

 

[ASbobcat]

I would love to think it was the firing pin but I have used max loads of RL15, LT32, H322 and N140 and this is the first time I have noted cratering.

How about any of the other signs I mentioned for confirmation? Of the four, I have always found primer cratering the least reliable. Lapua brass is very tough, second only to LC. If your primer pockets are still tight (.1710), you may also find primer "flattening" a more reliable indicator than cratering.

 

[M-61]

I have never paid much attention to primer cratering. Occurs with many rifles that I shoot. I note it but beyond that I don't do anything. There is also many versions of cratering. I am referring to a slight ridge around the indentation. I'd be far more concerned with a bolt lift that was stiff.

 

[ASbobcat]

I have never paid much attention to primer cratering. Occurs with many rifles that I shoot. I note it but beyond that I don't do anything. There is also many versions of cratering. I am referring to a slight ridge around the indentation. I'd be far more concerned with a bolt lift that was stiff.

Exactly

 

[Greyfox]

Looking for better accuracy out of my Savage LRPV I recently change powders from VVN140 to the Sierra's recommended accuracy load powder VVN540 and noted cratering on the most of the primers. The extent of the cratering was the same on all the primers regardless of the charge all the way to near max load with no other pressure signs noted on the brass.

Everything about the load was the same (Sierra bullet, CCI450 primer, Lapaua brass, jump)except the powder charges.

My question is: Is the cratering caused by the faster burning N540 powder causing a pressure spike even at a 1 grain charge below Sierra's max load numbers or do I have another problem I should be looking for.


Thanks for any and all thoughts!

W

The cratering can be dealt with. More important for now, did the accuracy improve? If it did, then your question might be, how do I correct it. If the accuracy was not better, then forget it and move on.

Rick

 

[wang243]

How about any of the other signs I mentioned for confirmation? Of the four, I have always found primer cratering the least reliable. Lapua brass is very tough, second only to LC. If your primer pockets are still tight (.1710), you may also find primer "flattening" a more reliable indicator than cratering.

None of the other four present. The primer pockets are still tight and I didn't have any flat primers.
Took a look at the PT&G bolt head and if it is a plug & play (no change in headspace) I may purchase one.

 

[wang243]

The cratering can be dealt with. More important for now, did the accuracy improve? If it did, then your question might be, how do I correct it. If the accuracy was not better, then forget it and move on.

Rick

Marginal improvement in accuracy in just this first load.

 

[Greyfox]

Maybe a stupid question, but are you using wind flags?

Rick

 

[Deleted old_dood]

Looking for better accuracy out of my Savage LRPV I recently change powders from VVN140 to the Sierra's recommended accuracy load powder VVN540 and noted cratering on the most of the primers. The extent of the cratering was the same on all the primers regardless of the charge all the way to near max load with no other pressure signs noted on the brass.

Everything about the load was the same (Sierra bullet, CCI450 primer, Lapaua brass, jump)except the powder charges.

My question is: Is the cratering caused by the faster burning N540 powder causing a pressure spike even at a 1 grain charge below Sierra's max load numbers or do I have another problem I should be looking for.


Thanks for any and all thoughts!

W

I have an LRPV and a Sav 12BR. From the factory they both came with oversized firing pin holes and both cratered the primers with any load. I put a PTG bolt face on one and sent the other to Gre'-tan for bushing. Cratering was cured on both.

 

[ASbobcat]

None of the other four present. The primer pockets are still tight and I didn't have any flat primers.
Took a look at the PT&G bolt head and if it is a plug & play (no change in headspace) I may purchase one.

I have found differences in PT&G bolt head depth vs Savage. It's not a problem for me since I set my own headspace. It's usually a small difference, a few thousandths one way or the other.

 

[Deleted old_dood]

the lugs on the PTG bolthead are a little longer so when I put one on my LRPV I had to adjust headspace. I later had a machinist friend of mine take a little off the back of the lugs to match the thickness of the Savage part and readjusted the headspace afterwards.

 

[Ned Ludd]

It's a Savage, which means the firing pin is almost as big around as a telephone pole. Use a magnum cup primer, get the pin bushed by Greg Tannel, or replace the bolt head. I would test out the results in that order, as simply using a primer with a harder cup may solve your problem, and bushing the firing pin hole isn't going to affect your headspace. Swapping out the bolt head is the most involved of the three procedures, and has the potential to cause the most change, so save that as the last approach.

 

[GrocMax]

It's a Savage, which means the firing pin is almost as big around as a telephone pole.

So .065"-.068" is considered telephone pole size?

 

[Ned Ludd]

. Relative to other brands of actions that never seem to have this problem.

 

[wang243]

. Relative to other brands of actions that never seem to have this problem.

Thanks guys for all the great info!!!!
I measured the pin (.067) and the hole thru the head is .073+(used a drill bit) so I called Greg and he is not bushing the Savage heads at this time(3 mos. out). I called PT&G and if I don't want to go thru redoing the head spacing it is a custom head at 125 and 6 to 8 weeks. I am waiting for Chris to call me back with the hole size on their head and then I will decide. I may wait for Greg and get one of his new firing pins and have it bushed in a few months.
As long as the createring is not a pressure indicator I will live with for now.
W

 

[GrocMax]

. Relative to other brands of actions that never seem to have this problem.

So tell us, which factory actions don't ever show any signs of cratering on SR primers?

 

[Ned Ludd]

It's well-established that Savage actions have large firing pin holes (relative). It's also well-established that this can cause cratering and/or pierced primers, even at relatively modest pressures. I personally know several individuals that have had to have their Savage rifle firing pin holes bushed by Greg Tannel, because they had issues with pierced or cratered primers. I don't know a single individual that has had this issue with a Remy 700 or other type of action. I never stated that you can't get cratered or pierced primers with other types of actions. What I stated was that it can be an issue with Savage rifles even at moderate pressures. It CAN happen with Savage rifles, it DOES happen with Savage rifles, and one of the reasons is the size of the firing pin hole. If you wish to debate this fact or start an argument, look elsewhere, I'm not interested in debating it with you.