6.5CM short OAL

[021411]

I finally got my comparator and OAL length gauge in and did some measuring on my rifle using 140gr ELD Match.

Base to Ogive (touching lands) = 1.9835" (COAL = 2.5985")

Backing off 0.020"..

Base to Ogive = 1.9635" (COAL = 2.5785")

Do the measurements seem a little short to y'all? The factory stuff I've been shooting is 2.81" COAL. Wouldn't that mean the factory loads are jamming into the lands? I'm shooting about 0.18" groups with the factory ammo.

 

[bschneiderheinze]

What bullet

 

[021411]

What bullet

Hornady 140gr ELD Match

Edited to clarify.. the factory loads I was shooting were the older 140gr A-MAX Match ammo. The bullet I am using to measure is the 140gr ELD Match. Still a huge difference in overall length.

I made some dummy rounds and there are occasional hangups chambering them in by hand and by mag. I'm getting about 0.011" of set back it seems. The bushing is 0.288" using once fired Hornady brass.

 

[bschneiderheinze]

You were getting .18 consistent groups from factory loads. What the hell are you shooting I want one. I load my 6.5 at 2.775 you must me measuring wrong have a carbon ring or something wrong with your caliber

 

[021411]

You were getting .18 consistent groups from factory loads. What the hell are you shooting I want one. I load my 6.5 at 2.775 you must me measuring wrong have a carbon ring or something wrong with your caliber

I said the hell with it and cleaned the chamber just to be sure. I'm still getting the same measurement. Hmmmm
Just to be clear I stop pushing the OAL gauge AS SOON AS I feel resistance. Any harder and the bullet gets stuck.

I'm shooting a Curtis Axiom with a 24" Bartlein 1:8 spun up by Alamo Precision Rifles. I can stack rounds on top of each other with this build.

 

[bschneiderheinze]

So you haven't tried to chamber a longer round like 2.7 to start with. My experience is sometimes hornady gauges don't work for shit.

 

[021411]

So you haven't tried to chamber a longer round like 2.7 to start with. My experience is sometimes hornady gauges don't work for shit.

Negative. Haven't tried 2.7" but I have a feeling it'll be jammed as well. Be right back..

 

[021411]

Ok I'm back. Loaded up a dummy round at 2.7" OAL (Base to Ogive 2.0845") and it chambered easily without issues. Looking at the bullet it is definitely hitting the lands. Measured before and after and it's about 0.0015" after slow chambering it twice. Nothing to write home about.

 

[bschneiderheinze]

I had to load the elds shorter than others bullets but I didn’t load many the 142 smk work way better for me. When measuring COAL I think you have to take into consideration they have a longer tip might start with 2.65 or 2.67. That’s not horribly short

 

[021411]

Thanks for the help so far. I also shot APR an email asking for suggestions. Maybe I should replicate the factory load and test it out. I mean it's shooting very well jammed into the lands.
I brought my LabRadar with me but only triggered it once. The bench setup at my local range is crap. I can't get good placement of the device in relation to the muzzle. I need to pick up a tripod. Anyway that one round clocked at 2750.

 

[LG65CM]

Hornady's Factory 140 ELD-M is 2.80" COAL, out of the box. 6.5CM. My rifle is an RPR. Loading to 2.80" puts my CBTO around .04X"s , depending on measurement using Hornady's tool.

If I read you right you are touching the lands with a COAL in the 2.7X's?? 'Sumthin' don't add up.....as your ogive should be way off the lands.

 

[021411]

Hornady's Factory 140 ELD-M is 2.80" COAL, out of the box. 6.5CM. My rifle is an RPR. Loading to 2.80" puts my CBTO around .04X"s , depending on measurement using Hornady's tool.

If I read you right you are touching the lands with a COAL in the 2.7X's?? 'Sumthin' don't add up.....as your ogive should be way off the lands.

Correct. I’m already touching at 2.6”. I used the gauge again and tapped a little firmer causing the bullet to stick which I had to push out with a cleaning rod. The land marks are there. COAL this time was 2.68”.

 

[XLR308]

Haven't seen any mention of reamer spec in regards to freebore.
Obviously not the .199" SAAMI spec, a call to APR should get you the info on what it was cut to.
Is the barrel marked with any additional info regarding chamber ?

 

[supercorndogs]

Is the barrel clean? That can affect your measurements.

 

[Seandradamus]

2 possibilities I can think of if you are measuring correctly.
1. You are not touching the lands even though it looks like it.You would know without a shadow of a doubt if factory ammo was jamming 200 thou
It would be difficult to even get the bolt all the way forward then hard to close.
I suspect a smallish diameter or carboned up freebore leaving scuffs.
Seat a bullet with lots of neck tension at 2.9
Try to close the bolt on it carefully if it doesn’t close or move forward with ease seat it 20 thou Deeper and try again, ignore slight scuffs and tiny movements until it chambers smoothly.
2. It was chambered with a zero freebore reamer and they forgot to throat it.

 

[nexusfire]

Is it a 5R barrel?

 

[021411]

Is it a 5R barrel?

Yes it is. The barrel was thoroughly cleaned as well. I’ll load a super long round after lunch and will try again.

 

[nexusfire]

I had this happen. Because of the 5R rifling, reamer chatter can happen when it is chambered and not all of the rifling gets cut evenly. This can be corrected by the gun smith by feathering the reamer back in there. I had a gun that was cut by the same reamer as my last one and the lands seemed about 0.070 shorter. That was the issue.

 

[021411]

I had this happen. Because of the 5R rifling, reamer chatter can happen when it is chambered and not all of the rifling gets cut evenly. This can be corrected by the gun smith by feathering the reamer back in there. I had a gun that was cut by the same reamer as my last one and the lands seemed about 0.070 shorter. That was the issue.

Interesting.. I did shoot APR an email to see what they say. Luckily they are a few hours drive away if I need them to check it out to be sure.

 

[nexusfire]

Also 143 eldx was crunching power with 42gr of h4350 in my normal 6.5 creedmoor

 

[021411]

2 possibilities I can think of if you are measuring correctly.
1. You are not touching the lands even though it looks like it.You would know without a shadow of a doubt if factory ammo was jamming 200 thou
It would be difficult to even get the bolt all the way forward then hard to close.
I suspect a smallish diameter or carboned up freebore leaving scuffs.
Seat a bullet with lots of neck tension at 2.9
Try to close the bolt on it carefully if it doesn’t close or move forward with ease seat it 20 thou Deeper and try again, ignore slight scuffs and tiny movements until it chambers smoothly.
2. It was chambered with a zero freebore reamer and they forgot to throat it.

Seated a dummy to 2.9" and it would not chamber at all.
2.88" NOPE
2.86" Can slightly begin to chamber. Can't close the bolt.
2.85" Can chamber and ease the bolt closed but not smoothly going slow but feels fine running bolt at normal speed. I am also seeing dark marks on the bullet. Guessing carbon from the lands.
2.84" Can chamber and close. Carbon marks noted.
2.83" Same.. Slightly less marks noted.
2.82" All seems normal but carbon still noted but less.
2.81" Factory length. It's fine. No carbon markings.

So what's next?

 

[Seandradamus]

Seated a dummy to 2.9" and it would not chamber at all.
2.88" NOPE
2.86" Can slightly begin to chamber. Can't close the bolt.
2.85" Can chamber and ease the bolt closed but not smoothly
2.84" Can chamber and close
2.83"-2.82" All seems normal
2.81" Factory length. It's fine.

So what's next?

Your lands are likely somewhere around 2.84
I would start at 2.85 again and take fine steel wool insert the bullet into it and spin, this will put fine scratches around the circumference and make it easier to see land marks. Insert close bolt and examine,...do you see 5 square rubs evenly distributed around the bullet , if so ,steel wool to remove , push back 5 thou and repeat, you will get a very accurate reading that way.
Or just load at 2.8 because ....a. It is shooting in the ones at that length. B. The bolt closes without issue therefore you are not in the lands.

 

[LG65CM]

Real curious to see how this turns out. Please let us know. My guess (knowing nothing) from another particpant here: "2. It was chambered with a zero freebore reamer and they forgot to throat it. " Good luck, lg

 

[021411]

Didn't have fine steel wool so I used 1000 grit sandpaper.
Started at 2.81" COAL.. I can clearly see the land marks. They are very visible and square.
2.794" Still see square land marks
2.789" a little less
2.784" a little less
2.779" almost gone
2.774" very light
2.769" very very light
2.764" BARELY any what I would consider land marks at this point. The marks are angled and not square.
2.759" - 2.719" light scratches. I think the bullet is off the lands at this point, maybe not, other than the light angled scratches.

 

[021411]

I was given the suggestion of carefully chambering a bullet in a case with loose neck tension. Doing it that way I'm getting 2.6580" COAL. With the Hornady tool I was getting 2.5985"-2.6180" so it's not far off I suppose.

Maybe I should start at 2.75" and add 10 thou to get into the lands and go from there.

 

[Deleted member 10043]

My .244 Remington does this with the Hornady tool. Once I have the case in and the bullet pushed forward with the gray rod until it stops keep it there with my left hand and use my right fingers on the brass bolt to push the case in further then tighten up to get consistent measurements. Just a reminder the Hornady case needs to be on there hand tight. Sometimes I catch it come loose.

 

[Kadams1563]

First off stop using COAL and use CBTO.

What brass have you been shooting?

I have about 1k of lapua brass down the chamber and have discovered I have a very bad carbon ring. This is even after detailed cleaning regularly. What I realized is that my Lapua brass was short from the factory and will not grow to even minimum length. This is causing a carbon ring and I am getting extremely short measurements.

I usually load to 2.200 CBTO.

 

[021411]

First off stop using COAL and use CBTO.

What brass have you been shooting?

I have about 1k of lapua brass down the chamber and have discovered I have a very bad carbon ring. This is even after detailed cleaning regularly. What I realized is that my Lapua brass was short from the factory and will not grow to even minimum length. This is causing a carbon ring and I am getting extremely short measurements.

I usually load to 2.200 CBTO.

I have. I listed the CBTO on the first post which is 1.9835". It still equates to a short OAL is which I'm trying to figure out. I've been using Hornady brass as I just went through a few boxes of factory ammo. I have no issues with getting Lapua brass but I need to figure this out first.

 

[021411]

2.76" OAL on top, 2.75" on the bottom.

 

[Seandradamus]

That does not look like a mark from engaging the lands .
I believe your initial measurements from closing the bolt on rounds measuring 2.85 and those just slightly causing resistance are more accurate in finding your lands

 

[Brux]

I'm thinking freebore also.

 

[Deleted member 10043]

Kadams, , Why do you continue to use brass that won't grow beyond minimum length? How long was it before you realized this?. Why does this create a carbon ring even with regular cleaning?

Anyway, all the OP is doing is trying is to learn how to use the tool properly. There, is nothing nefarious going on inside that rifle because of how accurate it is. Don't be afraid to jam the bullet and/or case up there with this tool.

 

[021411]

I'm going to start with 2.85" COAL/2.2320" CBTO since it can chamber and fit my mag. I'll load up a 10 shot ladder with that and work my down if need be. For sure I can't go 2.86"+ COAL because the bolt won't close.

I know for a fact that my rifle is a shooter with 41.5gr of H4350 at 2.81" COAL with 140gr A-MAX. Worse case I can work up an ELD-M load around that to see what it can do.

I'm still learning precision rifle reloading so this has been all educational. This is night and day compared to pistol reloading. I still believe I'm using the tool appropriately. If I tap the pusher any harder the bullet sticks and I have to push it out with a cleaning rod.

 

[Deleted member 10043]

It is okay that you have to push it back out with a cleaning rod. Not unusual at all. Get one of those cheap ass rods at Wal-Mart just for this purpose. Also, use CBTO when using that tool. COAL just confuses things more. Kadams is right about that.

 

[021411]

It is okay that you have to push it back out with a cleaning rod. Not unusual at all. Get one of those cheap ass rods at Wal-Mart just for this purpose. Also, use CBTO when using that tool. COAL just confuses things more. Kadams, is right about that.

Let me try tapping the "push rod" on the tool a bit harder before I retire for the evening.

 

[021411]

Alright.. I pushed on the rod until I felt the bipod load up a little. I had to knock the bullet out. This got me 2.1780" CBTO. Earlier today I got 1.9835" CBTO by lightly pushing the rod and immediately stopped when I felt resistance. It was repeatable.

 

[Deleted member 10043]

Repeatable is what we're looking for.

 

[Kadams1563]

Kadams, , Why do you continue to use brass that won't grow beyond minimum length? How long was it before you realized this?. Why does this create a carbon ring even with regular cleaning?

Anyway, all the OP is doing is trying is to learn how to use the tool properly. There, is nothing nefarious going on inside that rifle because of how accurate it is. Don't be afraid to jam the bullet and/or case up there with this tool.

Just about all of the new Lapua brass is short nowadays. They save money by making them a little short.

I do not know why they won’t grow lol. They just won’t get long enough to trim.

 

[Brux]

I had this same problem on a 6.5 I had built. The gun shot great but I could not get a consistent measurement with my Hornady gauges no matter what I did. Took it back to the smith who built it and he took his finish reamer and cleaned the freebore up and now it measures perfect every time. He looked at it with a borescope before doing so and said it was not a carbon ring. Bartlein barrel

 

[021411]

Theoretically speaking if I leave the things the way they are and load long into the lands, how much life will I take out of the barrel? I'm super impressed with it's accuracy.

 

[Deleted member 10043]

Nothing. Just chase the lands.

 

[LG65CM]

Just a thought- if possible, next time you go to the range, take your OAL guage, modified case and a new bullet, caliper, etc, with you . Ask a range officer if there is anyone there who has used the guage and have that person, ask that person, to take a measurement for you. See what they come up with.

 

[honuswagner]

I'm seating my ELD-M 140gr in Hornady brass to .11 jump and getting <.5 MOA groups at 100 yds. May seem like a bit of a jump but I'm on a AR-10 platform so limited by mag length.

 

[LG65CM]

I'm seating my ELD-M 140gr in Hornady brass to .11 jump and getting <.5 MOA groups at 100 yds. May seem like a bit of a jump but I'm on a AR-10 platform so limited by mag length.

Not to hijack thread,honuswagner, but I have been working on loads for and using my bolt gun. But, been limiting my COAL to 2.80-2.81 and hoping they would work out in my AR-10, also due to its mag length. My AR likes Hornady factory box 140 ELD-Ms and also Hornady's 140 HPBT American Gunner. Your post gives me some affirmation/ confirmation that my hope may come true. lg

 

[LG65CM]

Let us all know how it works out!

Will do. My shooting days are about over up here. But, am heading for AZ the end of the month. Once I get settled in there for the winter, I will get out to the ranges there and give these loads, I've got twelve worked up now, a go in my AR-10. I'm taking that rifle.

 

[021411]

Off topic from my own post but what velocity should I be looking at in general? More like ball park area. The factory A-Max was doing 1750 FPS. My barrel is 24” (Bartlein 1:8 5R).

 

[nexusfire]

Did you fat finger that or is it really 1750?

 

[021411]

Did you fat finger that or is it really 1750?

LabRadar said 1750. I have the lot number of the box at home. It’s older factory loaded 140gr A-Max.

 

[Kadams1563]

There is no way 1750 is accurate. Need another 1000 FPS.

 

[021411]

There is no way 1750 is accurate. Need another 1000 FPS.

Yeah you’re right.