Question?????

[Jim Beckley]

I was at a range a couple of weeks ago, the club hero was there with a Ruger Mark I in .257 Roberts, using some kind of factory ammo, I think that it was Hornady, but it was definetly +P ammo, I looked at the spent cases and everyone of them the primers was backed out of the case, with the firing pin hole tattoed in the primer, there was no other sign of pressure, no extractor marks the primer wasn't flattened or smeared! What do you think? One thing that I didn't do was look at the bolt face to see if it was beat up or not, this guy is the type if Tubb, Wigger and Sanchez was there he could have told them a thing or two about shooting.

Second question if the primer pocket it loose on your case on the average how much velocity do you think that it looses upon firing. It was got to let some of the gas escape to turn the case head black which you would think that some of the velocity would be lost?

[BCloninger]

It would be interesting to confirm that the primers were fully seated in the un-fired cartridges, but that's probably irrelevant anyway. One of the new custom recessed bolt faces?

[Jerry G]

Damn Jim........ You should have given me a call. I need some real good coaching from an expert. I need to be 're-trained'.

[Trent]

Isn't this a sign of under powered loads?

You aren't saying that the primers are pierced are you?

[lone ringer]

I was at a range a couple of weeks ago, the club hero was there with a Ruger Mark I in .257 Roberts, using some kind of factory ammo, I think that it was Hornady, but it was definetly +P ammo, I looked at the spent cases and everyone of them the primers was backed out of the case, with the firing pin hole tattoed in the primer, there was no other sign of pressure, no extractor marks the primer wasn't flattened or smeared! What do you think? One thing that I didn't do was look at the bolt face to see if it was beat up or not, this guy is the type if Tubb, Wigger and Sanchez was there he could have told them a thing or two about shooting.

Second question if the primer pocket it loose on your case on the average how much velocity do you think that it looses upon firing. It was got to let some of the gas escape to turn the case head black which you would think that some of the velocity would be lost?

Could it be a Ruger M99 Mark II Jim? My guess is that the rifle has excessive head space or the ammo is undersized. Some times when brass is smaller than the chamber we see weird things with the primers that appear to be signs of pressure.

[Jim Beckley]

I have a Ruger Mark II and it looked the same as mine, but his had a thumb slide safety just over the trigger, I asked him if it was a Mark I and he said yes. Could have been a head space issue.

[jjp]

I was at a range a couple of weeks ago, the club hero was there with a Ruger Mark I in .257 Roberts, using some kind of factory ammo, I think that it was Hornady, but it was definetly +P ammo, I looked at the spent cases and everyone of them the primers was backed out of the case, with the firing pin hole tattoed in the primer, there was no other sign of pressure, no extractor marks the primer wasn't flattened or smeared! What do you think? One thing that I didn't do was look at the bolt face to see if it was beat up or not, this guy is the type if Tubb, Wigger and Sanchez was there he could have told them a thing or two about shooting.

Second question if the primer pocket it loose on your case on the average how much velocity do you think that it looses upon firing. It was got to let some of the gas escape to turn the case head black which you would think that some of the velocity would be lost?

Could it be a Ruger M99 Mark II Jim? My guess is that the rifle has excessive head space or the ammo is undersized. Some times when brass is smaller than the chamber we see weird things with the primers that appear to be signs of pressure.

Agree with lone ringer on this one. I have seen this happen a lot with new brass and ammo combined with excessive headspace even with a lot of new rifles. Then the once fired brass is fine. The brass is a lot of the time way undersized and before the brass expands the primer pushes back.

[tenx9]

Headspace can be easily checked with go-no go gauge. Pressure is another story. If the primers are cupped thats a sure sign of pressure. Even if the primer has a slight haze to it with a flat primer, thats a beginning sign of pressure. If indeed it was factory ammo, its a sign a that the rifle can't handle that cartridge loading. Stay away from him while he's shooting it. I've seen rifles blow up and it ain't pretty. Maybe the steel of the action is fatiqued for whatever reason.

[RBriscoe]

I have seen this sort of thing on a number of occasions. Frankly it is no longer surprising to me to see it.

It is almost certainly the result of the nature of SAAMI "standards". The rifle manufacturers are afraid that those nasty old ammo manufacturers may produce some ammo towards the large end of tolerance in headspace and other chamber dimensions. They don't want any customer complaints about not being able to chamber factory ammo they picked up at the general store somewhere. They want the customer to be able to close the bolt and the rifle go "bang" so they make sure that the chamber is generously large.

The ammo manufacturers are concerned that the nasty old rifle manufacturers might make their chambers on the tight side that might cause a problem closing the bolt and they want the rifle to go "bang!" too so the make the ammo on the small size as insurance that they can close the bolt and so on.

By now you have guessed that for all the lofty purposes of SAAMI, the reality is that it assures mediocrity in far too many circumstances.

A number of years ago I was visiiting with a 'smith as he finished assembling a very nice .280 Rem live game gun. We took it outside to the test range and fire a shot. The primer was very badly backed ou and so we went back I solider and checked the headspace. It was just a couple of thou over "zero" headspace. We measures the chamber reamer and it was just a few thou over minimum headspace. We measured the headspace gauge and it was spot on. We measured the factory ammo's headspace and it was way below minimum!

The primer had backed out of the case almost 0.060 inches. The 'smith called his customer, explained the situation and offered several alternatives to the customer.

I have since measured a good bit of .243 Win and 7-08 brass. None of it measured as much as the "go" gauge. I presently have barrels head spaced to "zero" headspace using the brass I intend to use, not the headspace gauge. It does not concern me that my headspace might be less than SAAMI minimum. It works just fine and the rifle shoots excellently even when firing brand new brass.

You should understand what you are doing before asking your 'smith to do this, but I would find somebody else to do the work if they did not want to do it my way.

Note that you may have to grind down your shell holder or sizing die to get the headspace properly set to match that of the headspace set to properly match your chamber.

[Edited to correct thumb typing typos...silly cell phones.]

[Trent]

Great post Mr. Briscoe!

[Jim Beckley]

Yeah Rick, My rifles are headspaced to the brass that I'm using also (this also seems to eliminate trimming since the brass doesn't grow). With the barrels that you have put on, it's your choice what you want to do as far as chamber size (all the more if you have a reamer made to your specs), but with a factory barrel, you are pretty much stuck with what you get. One thing that surprized me was a buddy of mine had a Rem 700 ADL chambered in 7mm Mag, had a hard time chambering factory ammo in it. Started playing with it and found the factory ammo was headspaced at exactly 0, with a RCBS Precision Mic, the fired cases measured minus two thousands. He got around to taking it to a Remington authorized gunsmith and had the chamber opened up.

[BCloninger]

While reading RBriscoe's post, I began to wonder if the same thing has happened with small bore rifles and ammunition. A Remington 504 head spaced on a spent cartridge shoots far better than one set using the correct gauge and the bolt still closes fine - I had written it off as just another idiosyncrasy of the 504, but maybe not.

[Jim Beckley]

Well Bob, Sounds like a cash register is going to be opening somewhere?

[lone ringer]

I have seen this sort of thing on a number of occasions. Frankly it is no longer surprising to me to see it.

It is almost certainly the result of the nature of SAAMI "standards". The rifle manufacturers are afraid that those nasty old ammo manufacturers may produce some ammo towards the large end of tolerance in headspace and other chamber dimensions. They don't want any customer complaints about not being able to chamber factory ammo they picked up at the general store somewhere. They want the customer to be able to close the bolt and the rifle go "bang" so they make sure that the chamber is generously large.

The ammo manufacturers are concerned that the nasty old rifle manufacturers might make their chambers on the tight side that might cause a problem closing the bolt and they want the rifle to go "bang!" too so the make the ammo on the small size as insurance that they can close the bolt and so on.

By now you have guessed that for all the lofty purposes of SAAMI, the reality is that it assures mediocrity in far too many circumstances.

A number of years ago I was visiiting with a 'smith as he finished assembling a very nice .280 Rem live game gun. We took it outside to the test range and fire a shot. The primer was very badly backed ou and so we went back I solider and checked the headspace. It was just a couple of thou over "zero" headspace. We measures the chamber reamer and it was just a few thou over minimum headspace. We measured the headspace gauge and it was spot on. We measured the factory ammo's headspace and it was way below minimum!

The primer had backed out of the case almost 0.060 inches. The 'smith called his customer, explained the situation and offered several alternatives to the customer.

I have since measured a good bit of .243 Win and 7-08 brass. None of it measured as much as the "go" gauge. I presently have barrels head spaced to "zero" headspace using the brass I intend to use, not the headspace gauge. It does not concern me that my headspace might be less than SAAMI minimum. It works just fine and the rifle shoots excellently even when firing brand new brass.

You should understand what you are doing before asking your 'smith to do this, but I would find somebody else to do the work if they did not want to do it my way.

Note that you may have to grind down your shell holder or sizing die to get the headspace properly set to match that of the headspace set to properly match your chamber.

[Edited to correct thumb typing typos...silly cell phones.]

Rick, you have a way with words that explain without a doubt experiences that some of use tried to convey earlier in this thread with no success.

I have a rifle chambered in 7mm TCU that has a huge chamber and will close the bolt on a no go gauge but once the brass is fired formed and only the neck sizing die used to reload the ammo you would not know that there is a problem with the rifle.

[RBriscoe]

Yes, Tony, TC/U chambers were all over the place, but were not a problem once you fit (fire formed) the brass to the chamber as you did. It does illustrate the beauty of having your own reamer, ground to fit the brass and dies in the first place.

Merry Christmas and a Happy New Year to you, my friend!

Rick