Bolt face to cartridge base clearance

[Atarget1]

Hello and thank you in advance for the replies.
I am looking for a standard dimension between a cartridge base measurement and the bolt face measurement. Would say .016 be ok for clearance or should it be closer, like .005?
Is there a acceptable standard gap range?
Again, thank you

 

[fguffey]

Would say .016 be ok for clearance

I have one rifle that has .016" clearance. OK? For me, not a problem, I form cases with .014" added to the length of the case between the shoulder to the case head to get the magic .002" clearance.

I do not make it a habit but I was told I could not fire a case in a chamber with .127" clearance so I did, I was told I would get case head separation because; "THAT IS TO MUCH HEAD SPACE!

I have chambers that are go-gage length, I have cases that are minimum length, If I was talking about a 30/06 chamber the clearance would be .005". and if a reloader understood the Wilson case gage they would understand the difference between the two height from the datum is .005".

F. Guffey

 

[fguffey]

should it be closer, like .005?

Yes, the clearance for the 30/06 chamber is .005". When checking the chamber with gages I expect the clearance to be .0075" +/- a very few.

F. Guffey

 

[Atarget1]

Thank you all for the replies, but allow me to be more clear on my question.
I am looking for the acceptable clearance between the bolt face diameter and the cartridge base diameter.
The cartridge base measures .534 and a magnum bolt face is .550 a difference of .016 and the standard bolt face measures .484.
Sooo. would a magnum bolt be ok to use for the .534 based cartridge or should the standard bolt with a .484 measurement be opened up to the .534 cartridge?
If opened up what should the clearance be....540-.542??

 

[Dusty Stevens]

Gotta think about what extractor youll use cause once you open it up youll need to install one. Clearance doesnt matter as long as you have it and the extractor can grab it

 

[Atarget1]

Thank you Dusty and the rest that have answered.
As I continued looking and comparing different cartridges and bolts I found a gap from .004 to .016.
I am looking at another build, this time a 33 Nosler using the Remington 700 LA with a PTG bolt and Sako extractor. I found that the 33 had a cartridge base size of .534 and trying to match it to a bolt face size left a small gap or was too small to fit unless opened up.

 

[Roeder]

Thank you Dusty and the rest that have answered.
As I continued looking and comparing different cartridges and bolts I found a gap from .004 to .016.
I am looking at another build, this time a 33 Nosler using the Remington 700 LA with a PTG bolt and Sako extractor. I found that the 33 had a cartridge base size of .534 and trying to match it to a bolt face size left a small gap or was too small to fit unless opened up.

Actually measuring a variety of magnum cartridge cases I have on hand, 7MM STW, 338 Win Mag, Remington Ultra Mag; reveals base diameters from .522 to .540. I would say your clearance is right within the normal range using the standard .550 magnum bolt face.

 

[Atarget1]

Roeder,
Thank you taking the time and effort to measure those. Are they all shot from rifles with the magnum bolt face of .550?
I am looking and can't find a definitive answer on acceptable gap between a cartridge base and the bolt face.
An extreme to this question is, would it be safe to fire a .223 cartridge from a magnum bolt face? Given that everything else is good, chamber, headspace and barrel diameter?
Yes I know it is crazy, and I for one would NOT do this! Just trying to find an answer.....

 

[Hal]

atarg

It might work but why ?
You always have remember where your brain and eyes are when you fire the rifle.

Hal

 

[Atarget1]

atarg

It might work but why ?
You always have remember where your brain and eyes are when you fire the rifle.

Hal

Hal,
Sorry, I missed typing the word NOT now in bold in my statement above.

 

[Hal]

Hal,
Sorry, I missed typing the word NOT now in bold in my statement above.

Not a problem. Just want everyone to be safe.

Hal

 

[Kurz]

An extreme to this question is, would it be safe to fire a .223 cartridge from a magnum bolt face? Given that everything else is good, chamber, headspace and barrel diameter?
Yes I know it is crazy, and I for one would NOT do this! Just trying to find an answer.....

Given that everything was set up perfectly for the cartridge and rifle except the bolt face diameter, yes it will work. What does not function is the extraction of the cartridge case.

There are basically 4 separate brass cartridge rim diameters used in the U.S. The bolt face diameter will vary according the manufacturer of the rifle or action. Basically it needs some extra space to allow for variations in brass manufacturing and the style of extractor.:

0.378" for the .223 based cartridges
0.473" for the .308 based cartridges
0.532" for the standard belted magnum cartridges (7mm Rem. Mag., 300 Win. Mag.)
0.590" for the Lapua based cartridges including the 300 and 338 Norma Mags.

It is obvious that brass manufacturers use their own dimensions for manufacturing yielding variations but there are suggested standards established by SAAMI.

http://www.saami.org/specifications_and_information/index.cfm

Remember that your stated '0.016' is the total diameter which is actually only 0.008" per side. This is not very much when you consider that the firing of cartridges creates quite a bit of dirt and fouling. On average, a human hair* measures 0.004" in diameter approximately, so the space is about 2 human hairs per side. Yet we expect the action to feed and run every time. In essence, we create the extra space around the case rim in order to accommodate dirt and fouling yet allow the action to function correctly and the case to seat properly against the bolt face.

There are exceptions to all things and this topic is certainly no different. We have the PPC bolt face (0.445") and the 30 Remington bolt face (0.422" for the 6.8 SPC). And last but not least, a single strand of RED hair often is oval in shape so it doesn't have a diameter as such but 2 dimensions for measurement.

Enjoy the process!

 

[Atarget1]

Given that everything was set up perfectly for the cartridge and rifle except the bolt face diameter, yes it will work. What does not function is the extraction of the cartridge case.

There are basically 4 separate brass cartridge rim diameters used in the U.S. The bolt face diameter will vary according the manufacturer of the rifle or action. Basically it needs some extra space to allow for variations in brass manufacturing and the style of extractor.:

0.378" for the .223 based cartridges
0.473" for the .308 based cartridges
0.532" for the standard belted magnum cartridges (7mm Rem. Mag., 300 Win. Mag.)
0.590" for the Lapua based cartridges including the 300 and 338 Norma Mags.

It is obvious that brass manufacturers use their own dimensions for manufacturing yielding variations but there are suggested standards established by SAAMI.

http://www.saami.org/specifications_and_information/index.cfm

Remember that your stated '0.016' is the total diameter which is actually only 0.008" per side. This is not very much when you consider that the firing of cartridges creates quite a bit of dirt and fouling. On average, a human hair* measures 0.004" in diameter approximately, so the space is about 2 human hairs per side. Yet we expect the action to feed and run every time. In essence, we create the extra space around the case rim in order to accommodate dirt and fouling yet allow the action to function correctly and the case to seat properly against the bolt face.

There are exceptions to all things and this topic is certainly no different. We have the PPC bolt face (0.445") and the 30 Remington bolt face (0.422" for the 6.8 SPC). And last but not least, a single strand of RED hair often is oval in shape so it doesn't have a diameter as such but 2 dimensions for measurement.

Enjoy the process!

Kurz,
Thank you for taking the time for that information!
While working in the aerospace industry I am use to working with tolerances for a given measurement. The quest for an answer to my question has brought many answers on different forums but what has been constant is "as long as it fits you're good to go" has been the replies.
I was questioning if there was/is a standard dimension range for a given bolt face to cartridge base. This query is being driven for me to have the best of both worlds, accuracy and functionality. Removing as much "slop" but still having a rifle that will function properly and safely.

 

[Roeder]

Roeder,
Thank you taking the time and effort to measure those. Are they all shot from rifles with the magnum bolt face of .550?
I am looking and can't find a definitive answer on acceptable gap between a cartridge base and the bolt face.
An extreme to this question is, would it be safe to fire a .223 cartridge from a magnum bolt face? Given that everything else is good, chamber, headspace and barrel diameter?
Yes I know it is crazy, and I for one would NOT do this! Just trying to find an answer.....

Sorry I took so long to answer. As far as I know, Remington only makes one standard magnum boltface, so yes all these cartridges can work with the standard boltface. As to the .550 diameter; the way that the bolt is machined to accept the extractor makes it difficult to measure an exact diameter. There is a small section opposite the extractor that actually supports the rim against the extractor clip, so the .550 dimension may be a bit misleading. It is sometimes necessary to bend or tweak the extractor so that it snaps over the case rim easily but securely.
To answer your question about an extreme mismatch such as a .223 fired in a magnum boltface: Such a mismatch would normally result in nothing worse than no extraction, but in the event of a case failure from extreme pressure ( such as might be caused by using a pistol powder by mistake), the "3 rings of steel" design intent would be compromised and there might be considerably more gas blowback.
Several of the custom action makers (BAT for one) offer a "Universal bolt face" of .480 diameter which works with both the standard .308 case diameter of about .470 and the PPC case which usually runs about .440. So .040 seems to be safe. There certainly is not a reason to worry about the .016 total clearance that your original post asked about