Need help with 300 Win Mag COL

[crazyj789]

Hello Ingo

I have a Savage action with a criterion 24" 300 Win Mag barrel on a XLR chassis. The loads I'm putting together are 225gr Hornady BTHP Match. I'm very new to reloading and was doing a little research on how to measure my rifles COL to the lands and start at .010" to .015" off the lands. I took a once fired piece of brass with no case prep what so ever and put a fresh bullet in the neck. I pinched it a little to hold the bullet in place. I then took a marker and colored the bullet. I put it in my rifle and closed/opened the bolt slowly to get my measurement for COL to the lands which was an average of 3.492". Upon reading the Hornady 9th edition reloading manual it states that a MAXIMUM COL of 3.340" for the 225gr loads. IF I take my COL to the lands minus the .015 I want to start with I get 3.477" which is 0.137 bigger than the MAXIMUM COL listed in the manual. My questions are...

Is my rifle screwed up?

Head spacing wrong?

Is the difference because of no case prep?

Is it normal to have that much of a difference in rifles actual COL to lands minus .015" to MAX COL listed in the book?

Thanks in advance....Jason

 

[SSGSAD]

The only thing I can think of, is fire factory ammo, and resize the case, and repeat what you just did....

 

[crazyj789]

The factory ammo that I was using is Black Hills 190gr match and I was printing 1.5" groups. I want to work up my own loads to see if I can tighten things up a bit.

 

[crazyj789]

My current unprepared case length from one firing is 2.615" and the Hornady book states MAX case length of 2.620" and trim length of 2.610"

 

[sht4brnz]

I used your method of measuring the chamber, but found it wasn't accurate or consistent enough. The Hornady oal gauge is very useful. My chamber is also about 3.500" oal. Your rifle is not screwed up.

Hornady Lock-N-Load Overall Length Gage Bolt Action

You will need the modified 300WM shell in conjunction with the tool

 

[crazyj789]

I used your method of measuring the chamber, but found it wasn't accurate or consistent enough. The Hornady oal gauge is very useful. My chamber is also about 3.500" oal. Your rifle is not screwed up.

Hornady Lock-N-Load Overall Length Gage Bolt Action

You will need the modified 300WM shell in conjunction with the tool

If your chamber is 3.500 OAL then what are you loading for OAL? From what I gather my bullet jump using 190gr Black Hills match is like 0.151 which seems really, really, really out of spec

 

[sht4brnz]

The cartridges I make for my rifle chamber are
With 220smk the oal is 3.490.
With 230 Berger's the oal is 3.750.
The ogive of the bullet is what touches the rifling of the bore. The profile of each bullet is different hence the variance in oal.
Factory ammo and loading manuals will adhere to SAAMI specs, to be safe in all rifles. All rifles will have a bit of variance of free bore but none will be under SAAMI spec. A bullet jammed in the rifling is an overpressure concern.
A lot of newer 300WM chambers have more free bore to allow for heavier projectiles and keeping the room in the case for powder.
Use the manual for starting reference for powder. Start your loads just touching the lands. Monitor your brass for pressure as you work up your powder. Find your node, then begin fine tuning your powder charge, then start tuning your bullet jump by moving the projectile back in small increments.

 

[crazyj789]

The cartridges I make for my rifle chamber are
With 220smk the oal is 3.490.
With 230 Berger's the oal is 3.750.
The ogive of the bullet is what touches the rifling of the bore. The profile of each bullet is different hence the variance in oal.
Factory ammo and loading manuals will adhere to SAAMI specs, to be safe in all rifles. All rifles will have a bit of variance of free bore but none will be under SAAMI spec. A bullet jammed in the rifling is an overpressure concern.
A lot of newer 300WM chambers have more free bore to allow for heavier projectiles and keeping the room in the case for powder.
Use the manual for starting reference for powder. Start your loads just touching the lands. Monitor your brass for pressure as you work up your powder. Find your node, then begin fine tuning your powder charge, then start tuning your bullet jump by moving the projectile back in small increments.

Here is some data that I have gathered so far with a pic....The case in pic to the left is covered with black marker and is a once fired case with a 220gr smk in it. When I close/open my bolt on the bullet it gives me a consistent 3.501" OAL to the lands of my rifle (you can see the ring in the pic on the bullet from the rifling). The casing on the right is a factory loaded 190gr Black Hills match that has a OAL of 3.318" which is I assume SAMMI spec. So going off your info I have a decent amount of free bore to play with and this is NOT an issue? I can safely load this 220gr SMK to say 0.015" off the lands and start at the bottom of the powder chart and work my way up looking for pressure signs? It seems that the 30gr difference in bullets and the extreme VISUAL OAL differences just have me worried because the Hornady book lists a 3.340" OAL for even their 225gr projectile. Sorry for being such a noob guys but all the info is really helping.

It also seems to me that the O-give on the round to the right would have a HUGE bullet jump judging by the differences in the OAL between the two rounds

 

[sht4brnz]

you're on the right track

 

[sht4brnz]

consider getting the oal tool. I was getting repetitive measurements only to find that they were far from accurate. the bullet would get stuck in the lands and pull out of the case just a bit every time I would remove it from the chamber

 

[crazyj789]

consider getting the oal tool. I was getting repetitive measurements only to find that they were far from accurate. the bullet would get stuck in the lands and pull out of the case just a bit every time I would remove it from the chamber

I got one on order...thanks for all your help!

 

[spaniel]

I use a method similar to yours. I make a dummy round and just seat the bullet a tiny bit deeper until the bolt closes and back off my desired distance from there. Never had an issue. The tool is nice but I also have rounds that they don't make modified cases for so I'm already using my own methods.

The book is giving you values that are just that -- book. Throats are not cut to a standard length. My 300WM rounds likely could not be chambered in some guns but they are perfect for mine, which has a long throat that Remington factory guns are known for. There is nothing to be concerned with your gun having a long throat. Just don't handload ammo for it then use it in a different gun -- where you may jam a round up into the lands.

The only down side of seating your bullets out to sit correctly off the lands is that you may run out of magazine length.

 

[RMC]

The COL really doesn't matter much. The only bearing it has is determining if the cartridge will fit in the magazine. The cartridge itself seats on the band at the base of the brass. If you can seat the bullet a few thousandths off the lands consistently and the cartridge still fits in the magazine then you should be golden.