Projectile Ogive Measurements

N

ninosdemente

New member
So I am using Hornady OAL gauge/comparator and the 6.5 creedmoor modified case by Hornady. Before I was loading by book. Now have I just started loading to ogive.

Using Hornady Match 140gr and Nosler RDF 140 gr. On average I am getting 1.985" from base of brass to ogive for Hornady and 1.980" from base of brass to ogive for Nosler. Now I have Hornady American Gunner factory ammo 140 gr and when chambering 3 rounds do see the projectile have marks. http://www.mentegraphics.com/pictures/116.jpg

For curiousity, I measured the base of brass to ogive for those 3 rounds and come up with 2.200" average if applicable. I have not made any sample rounds yet, but just comparing factory and what I have measured, the projectile is more seated inside the brass. The final look of the roud seems odd to me. If measured correctly, that should be ok? Also, when adding powder, would this be of concern given the projectile is seated deeper than factory? Since previously I was shooting 80% factory ammo, that my ogive measuring results looks like an odd round, almost a mini round if that expression can be used.

Rifle: Savage 12FV 6.5 Creedmoor

Am I doing something wrong or does this happen sometimes? Sure does feel like I am doing something wrong. Thanks in advanced.
 
Is the bolt hard closing on those 3 factory rounds? those marks look like they are from the feed ramp. The marks don't look to be all the way around the bullet.
 
26 caliber (6.5mm) bullets normally don't touch the rifling at any diameter less than .256 inch. Mic your bullets scratches diameter, any scratch points less than .256" were not made by rifling.

Rifling typically leaves scratch points evenly spaced around bullets. One for each land. 6 groove barrels make six scratch points.

Rimless bottleneck ammo is against the chamber shoulder when fired. Its head is X thousandths off the bolt face when fired. If your ammo of all exact head to bullet length of some sort has. 004" spread in head to shoulder dimension, that spread transfers to where the bullet rifling touch point is.

A few thousandths spread in bullet to rifling jump when fired is insignificant unless your biggest groups are under 1/4 MOA at 100 yards.
 
1- take a sharpie, color the bullet with it
2- chamber the bullet in a sized case without primer or powder, eject it, look for marks on the bullet missing the coloring. If there are marks like on the pics you posted you are hitting the lands.
3- Pull the bullet with a hammer puller and reseat the bullet .005 deeper go to step 1
4- repeat until marks disappear.

You can fine tune using the same method. Easiest and most foolproof way I have found to find lands. If during the initial process you get resistance closing the bolt you don't need to force it, just eject and go to step 3. Sounds like you are just kissing the lands already

I am a huge fan of the KISS principle
 
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One thing I found helpful was switching to the Sinclair stainless bullet comparator inserts. They fit the Hornady base and are cut to more closely match a typical throat. For that reason, they contact the bullet ogive further down than the aluminum inserts from Hornady, but comparative measurements give me slightly better consistency from them and measuring the bullet where it actually will touch the lands gives me more confidence I am comparing apples to apples.

The edge of the entry to the freebore of the throat can sometimes scuff a bullet on one side. Rifling marks show clearly as mirroring the individual lands if you are actually in the throat.
 
When chambering the factory rounds do it by just feeding them directly into the chamber by hand. This will eliminate any scratches from the magazine/feed ramp. I have the same rifle and have used both of those bullets and my original base to datum measurement on a new barrel was 2.223". Right now after many rounds it's at 2.295".
 
Those marks on the bullet' are not land marks! I think sako2 hit it right right off. Something I would question. You said those rounds you showed were factory rounds yet they are longer measurement than what your already loading? In my Hornady book it say's the Max COL is 2.80". I would think the round's you loaded and the factory rounds would be jammed into the lands at what you measured to the ogive? You measuring them right? I think you'll find every COL in every book is the same which make's everything you shoot fit and magazine of any rifle and keep's the bullet's off the lands.
 
UN said:
One thing I found helpful was switching to the Sinclair stainless bullet comparator inserts. They fit the Hornady base and are cut to more closely match a typical throat. For that reason, they contact the bullet ogive further down than the aluminum inserts from Hornady, but comparative measurements give me slightly better consistency
Click to expand...

+1 on that , I however found there case headspace inserts ( head to datum measurement ) harder to deal with then the Hornady inserts . They "seemed" less consistent and were giving me numbers that did not give with my headspace gauges so I stopped using them but I love there ogive inserts .
 
I've never cared how far off the land's I am just that I am off the lands. But even though I measure COL, I can still tell about how far off the lands I am. I seat the bullet in short segment's till there are no more land marks on the bullet. If you measure the COL every time you seat the bullet a bit deeper, sub tract the shorter number from the larger number and that's how far you are off the lands. Myself I don't worry about it, I simply want the bullet off the lands a bit. Keep in mind to do it you have to use the same bullet over each time. 0000 steel wool removes land marks nicely!
 
How much does a 6.5 Creedmore's accuracy degrade as a given load's jump to the lands increases .060" after a couple thousand rounds?
 
I did hand feed them, then when closing with bolt, the marks still appear. The one variable I am trying to determine is my bolt as I have been having stiff problems.
 
Here is testing with marker... using same brass and same projectile. All these were hand fed. On one that I hand fed, I was able to remove it again before closing with bolt just to see if my hand cause any markings at all and none showed up. I am using Lymans which mentions the COAL at 2.825".

This is measuring from the base of brass to projectile ogive and took picture of opposite sides.

2.2005"
http://www.mentegraphics.com/pictures/117.jpg
http://www.mentegraphics.com/pictures/118.jpg

2.1505"
http://www.mentegraphics.com/pictures/119.jpg
http://www.mentegraphics.com/pictures/120.jpg

2.100"
http://www.mentegraphics.com/pictures/121.jpg
http://www.mentegraphics.com/pictures/122.jpg

2.0495"
http://www.mentegraphics.com/pictures/121.jpg
http://www.mentegraphics.com/pictures/121.jpg

2.0005"
http://www.mentegraphics.com/pictures/126.jpg
http://www.mentegraphics.com/pictures/125.jpg

1.980"
http://www.mentegraphics.com/pictures/127.jpg
http://www.mentegraphics.com/pictures/128.jpg

1.955"
http://www.mentegraphics.com/pictures/129.jpg
http://www.mentegraphics.com/pictures/130.jpg

1.935"
http://www.mentegraphics.com/pictures/132.jpg
http://www.mentegraphics.com/pictures/133.jpg

1.920" (only picture from one side at different angles)
http://www.mentegraphics.com/pictures/134.jpg
http://www.mentegraphics.com/pictures/135.jpg
 
Thanks hounddawg. From Barts explanation of rifling that I should have seen even marks that are not shown on pictures, then there is no indication of rifling. What can be concluded then? What else can I possibly do to find out what is causing those scratches?
 
probably just from feeding nino, I don't sweat the small stuff. You know where the rifling starts, just use that as a reference and play with depth to get the groups where you want them
 
"...Those marks on the bullets are not land marks!..." Not even close to being land marks. Look more like scratches from the gauge.
Fortunately, that measurement doesn't mean much of anything anyway. OAL is not measured to the ogive. The ogive will be different with every style of bullet. OAL is measured from the flat part of the case to the pointy end part of the bullet. Not the ogive.
 
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