UPDATED (see 1st post) - "To the lands" measurement question

[PigPknHeat]

I wanted to see how long I could seat some 175gr SMK 308s so I used my Hornady Comparator and found that 2.230" to the ogive is when it touches the lands. My question or concern is that the factory loaded Federal Gold Medal Match 175 SMKs are seated at 2.228" to the ogive. This was not what I was expecting, I thought I would have some more room in there.

Thoughts?

Rifle is a new Savage 10t.

UPDATES BELOW

Pulled SMK vs New SMK (using Hornady Bullet Comparator OAL Tool)
Bullet Base to tip: 1.234" vs 1.234"
Bullet Base to Ogive: .667" vs 0.644"
Seat Ogive to Lands: 2.208" vs 2.231" Makes for OAL 2.778" vs 2.819"

Factory Fed. GMM is seated to 2.228" (Ogive) which puts it into the lands at about .020". Chambered rounds do show rifling marks once chambered.

 

[mac1911]

I wanted to see how long I could seat some 175gr SMK 308s so I used my Hornady Comparator and found that 2.230" to the ogive is when it touches the lands. My question or concern is that the factory loaded Federal Gold Medal Match 175 SMKs are seated at 2.228" to the ogive. This was not what I was expecting, I thought I would have some more room in there.

Thoughts?

Rifle is a new Savage 10t.

i would think you have a nice tight chamber ?
Will you be single loading or loading from a magazine. I shoot cast bullets in my 1903a3 it will shoot a bit more consistent groups if i seat just off the lands, yet i need to shoot from the magazine for rapids so i end up about .030" +/- .005" off the lands.

 

[PigPknHeat]

Ill be rechecking tonight to be sure...

But the goal is to use this rifle to introduce me to long range shooting. I figure a 175gr smk or 178gr ELDX would benefit from a custom steated load maybe have a little extra room for some more powder. I plan to take an upcoming class with EC but works been busy, going to try and catch the one in march.

 

[mac1911]

I don't really load for to many rifles other than my military surplus stuff and most bullets can't even reach the worn throats on these old guns.
I load 80 grain Noselers in my AR and found my gun and and load like a little jump

 

[PigPknHeat]

Checked it again (exact same bullet) this time giving good firm pressure to the case with the Hornady OAL gauge and slight pressure to the bullet. Got 2.233" to to the ogive. Remeasured some Fed GMM 175s and got the same measurement as before (2.228" to ogive) i did find one in the box out to 2.230"

Still unsure if this is a safe distance from the lands to use the factory GMM ammo. With unknown charge from factory if it gets into the lands will it be over pressured?

 

[mac1911]

Checked it again (exact same bullet) this time giving good firm pressure to the case with the Hornady OAL gauge and slight pressure to the bullet. Got 2.233" to to the ogive. Remeasured some Fed GMM 175s and got the same measurement as before (2.228" to ogive) i did find one in the box out to 2.230"

Still unsure if this is a safe distance from the lands to use the factory GMM ammo. With unknown charge from factory if it gets into the lands will it be over pressured?

are you sure your bullets and the GMM are the same? pull a GMM round and try seating that bullet in one of your cases.

 

[PigPknHeat]

I will be doing that next maybe tonigjt if i get home in time

 

[mac1911]

I will be doing that next maybe tonigjt if i get home in time

i would pull a bullet and measure the ogive from base of the GMM bullet to ogive and compare it to your bullets. theres no certainty that just because they are both 175smk the ogive will be the same.
heck the GMM might be a specific production run from sierra with a different jacket or other spec vs the out the door production

 

[noylj]

Pull the factory ammo bullet out a bit and determine what the max COL is for the factory ammo and that is a quick way to see if the ogive/meplat is the same.
I, personally, have not seen any pressure signs when loading near or against the lede. If you have fired the factory ammo and not seen any pressure signs, then you are OK.
Then again, the "expert" say that rifle cases are so large that there is negligible difference in case capacity loading to a shorter COL and pressure goes down because there is more free bore and pressure goes up by loading long. Be nice if SOMEONE actually published some test results.
Years ago, standard practice with a bolt action was to load until you had difficulty lifting the bolt (definite high pressure sign) and then decreasing the charge by 0.5-1.0gn. These were loads that when pressure tested came up to about 75000 psi, and yet, that was standard for almost 90 years or more.

 

[wahsben]

www.youtube.com/watch?v=TWmIwPwLyyg

 

[5 DOLLAR FOOT LONG]

I would not worry about it. I have loaded 5.56 so the ogive gets forced 5 thousandths into the rifling when chambered...

 

[DukeInFlorida]

Get yourself some CERROSAFE metal, and do a chamber casting. That will give you easy to measure dimensions:

http://www.brownells.com/gunsmith-t.../cerrosafe-chamber-casting-alloy-prod384.aspx

or

https://www.midwayusa.com/product/462291/midwayusa-chamber-casting-alloy-1-2-lb

Either one melts about 160 degrees, F, and is re-usuable. I do lots of chamber casts.

I also has a dentist buddy tell me that he uses the same two part pink stuff (Algenate) that they use when making the form for a crown.
https://www.net32.com/ec/masterdent...Nu-PsvrgRJc7ig8LhE5hB_XyUIuxE6ey3GRoCHxPw_wcB

 

[mac1911]

Get yourself some CERROSAFE metal, and do a chamber casting. That will give you easy to measure dimensions:

http://www.brownells.com/gunsmith-t.../cerrosafe-chamber-casting-alloy-prod384.aspx

or

https://www.midwayusa.com/product/462291/midwayusa-chamber-casting-alloy-1-2-lb

Either one melts about 160 degrees, F, and is re-usuable. I do lots of chamber casts.

I also has a dentist buddy tell me that he uses the same two part pink stuff (Algenate) that they use when making the form for a crown.
https://www.net32.com/ec/masterdent...Nu-PsvrgRJc7ig8LhE5hB_XyUIuxE6ey3GRoCHxPw_wcB

you can also suck the flavor out of the masterdent when done, nice minty chamber cast....