Chamber length question

[Lennyjoe]

Using the old method of checking chamber length (majic marker and fired brass) I came up with 2.500 for my 22-250. The bullets Im using (50gr V-Max) shows an O.A.L. of 2.350 in the reloading manuals. Thats .150 off the lands. To me that sounds pretty extreme.

So what is the usual clearance between lands and bullets? I know the type of bullets plays a major part but .150 just sounds extreme to me.

If I wanted the bullet .010 off the lands I would have to seat the bullets on the 50gr bullets to 2.490 which seems odd.

Is it me or do I suck at math?

BTW, I just ordered a Stoney Point set up for proper measurments today.

 

[dakotasin]

i let the bullet tell me what the col is s'posed to be.

i seat the bullet very long on an inert case, force it into the gun, slam the bolt closed, and what you eject is a start point. keep going progressively deeper until you are happy.

all of my handloads are far longer than both factory loads and book-listed max col's... interestingly, my handloads are far and away more accurate, too.

 

[Lennyjoe]

I've done that too. Thats how I got the 2.500 for the 50 gr V-Max.

I also did that with 55gr V-Max and started at 2.490 and blew primers out the back end of the brass. Killed the ejector spring and kicked the extractor out of position. No bulging of the brass at all either. I dont know if it was the brass, primer pocket or too much pressure due to the bullet being so close to the lands. It was .010 off of the lands.

 

[Bullet]

Lennyjoe
When measuring the distance from the bolt face to the lands using an empty cartridge you’re really measuring to the ogive on the bullet. This is the measurement you want to go by to seat your bullets. To measure this you need a caliper and a comparator. You do not want to measure the cartridge over all length because the COL doesn’t tell you the distance to the ogive of your bullets. When loading different weight or different brands of bullets the COL measurement will be different. Sounds like you seated your bullets (55gr) into the lands.

 

[Lennyjoe]

I did a little more reading on C.O.L. and chamber length and am waiting on the Stoney Point stuff to come in.