6.5 Grendel Reloading question

[svxwilson]

I have a Precision Firearms 6.5 Grendel that I have had for a few months now and have finally got through the recommended break in period specified by Mark H the owner of Precision. I have around 100 rounds through it now. On average It shot .5-.75 moa every group through break in. I think the worst group was around 1 moa and that was me causing that. So it is basically my most accurate rifle I own.

I reload and have recently began to use a few of Hornadys reloading lock and load tools. I have been measuring the bullet jump using the bent col tool and the bullet comparator for accurate readings involving distance the bullet travels before it reaches the lands of the rifling.

I had not had a chance to measure the distance in the Grendel because I didn't have the threaded 6.5grendel dummy case to fit the COL tool. I sent hornady a fired case and $15 and they made me a custom one fired from the gun it will be measuring later. I received this case today and measured my Grendel.

It has a HUGE bullet jump of almost .2" So my measurement for where the lands are was 1.845 when the bullets are loaded to 1.688 they barely fit in the mag. I have a pic of the dummy round, a hand loaded round, and a factory Hornady round all with the 123gr Amax.

This is basically a brand new rifle, it has a Bartlein barrel. I have been very happy with it. No FTF, amazing accuracy, smooth easy to shoot rifle. Should I be concerned with the amount of jump this has already without any real barrel wear? I have always cleaned it with a bore guide. I have taken excellent care of it. This and my SCAR are my most prized items.

Is this common with a 6.5 Grendel? I only have reloading experience with the 3 other gas guns I own, but none of them have any thing near the amount of jump the Grendel does???

 

[WildBill3/75]

6.5 Grendel Forum : : For the 6.5 Grendel Aficionado

That sounds way way off...I measured my distance to lands using 123amax's in a case I loosened the neck on chambered in the rifle with the ejector removed over 12 measurements ....I was getting a COAL of 2.271 to touch lands. I found my rifle likes a COAL of 2.251. Also using a PF barrel(20" Lilja)

 

[svxwilson]

I zero my calipers on the hornady tool and I use a bullet comparator kit. It uses the ogive as the reference point on the bullet. Not the tip. as you can see its not that outa whack. So by the given measurements 2.414 is where my lands start.

 

[country888]

I'll be honest, I love the hornady bullet comparator and head space guages, but I dislike the dummy case for measuring OAL. I tried one with my 25-06 and keep getting false reading so I dumped it. Use the old stand by, get yourself a wooden dowel rod and 2 rod stops. Measure from your muzzle to bolt face, set rod stop, then measure to the bullet nose where it just touches the lands and set the other stop and measure the distace between the stops minus the thickness of one of the stops. This is the best most accurate way I have found that works every time. This is a cheap and accurate way of measuring the OAL for any cartridge without any special tools for different calibers. It also takes the the dummy case variable out, is the case seating right and all the way. Would the case head be touching the bolt face? With the dowl rod method there is no wondering. Just my 2cents

Awesome looking grendel by the way! They are a great shooter for sure! I have hundreds of rounds through mine now and still love dinging steel with it. Its a super round.

 

[svxwilson]

I'll be honest, I love the hornady bullet comparator and head space guages, but I dislike the dummy case for measuring OAL. I tried one with my 25-06 and keep getting false reading so I dumped it. Use the old stand by, get yourself a wooden dowel rod and 2 rod stops. Measure from your muzzle to bolt face, set rod stop, then measure to the bullet nose where it just touches the lands and set the other stop and measure the distace between the stops minus the thickness of one of the stops. This is the best most accurate way I have found that works every time. This is a cheap and accurate way of measuring the OAL for any cartridge without any special tools for different calibers. It also takes the the dummy case variable out, is the case seating right and all the way. Would the case head be touching the bolt face? With the dowl rod method there is no wondering. Just my 2cents

Awesome looking grendel by the way! They are a great shooter for sure! I have hundreds of rounds through mine now and still love dinging steel with it. Its a super round.

I agree the tools are difficult to get accurate readings, however I found a way that deliver accurate readings every time with the dummy case on 2 different AR's and my SCAR 17. It took a few weeks of frustration before I thought up my method after reading and watching others use the same tools. So I am confident about the numbers delivered. I think I will try your method as well to have a second reference.

Thanks for the compliment. I will let her know you enjoyed the pic

 

[country888]

View attachment 20568View attachment 20569View attachment 20570
I zero my calipers on the hornady tool and I use a bullet comparator kit. It uses the ogive as the reference point on the bullet. Not the tip.View attachment 20571 as you can see its not that outa whack. So by the given measurements 2.414 is where my lands start.

Looking at your pics im not sure what your doing. After you run the bullet up to the lands where are you measuring to. Tip or ogive? It doent really matter as long as you stay consistent and not measuring apples and comparing them to oranges. If your measuring to the ogive your OAL will be shorter than someone's that is measuring to the tip. To see for sure, load a blank round (no primer or powder) set the OAL to 2.415 and color the bullet with a black sharpe and chamber it, extract it and look for rifle marks, hard extraction.

 

[svxwilson]

Those pics are just showing how the factory rounds and some hand loads with lapua brass measure up with the bullet comparator. I didn't take any pics of the round measured with the col tool, it was difficult with the dummy case.

 

[country888]

Cool.. If you try the dummy round with a sharpe let us know how it did. I believe your getting your measurment off somewhere. I have a saturn barrel and most of bullets arn't off lands but .005" to .020" depending on bullet. Im sure you'll get it figured out. Good thing is you know it shoot great!!

 

[msalm]

When I build precision AR's, I take a cut-off section of the barrel blank used on the rifle and run the chamber reamer in up to the shoulder/body junction. It takes all of a few minutes and then you have a perfect chamber guage without trying to chamber rounds in the rifle itself.

 

[Fried Chicken Blowout]

Good input above... My input is similar... Stick to apples to apples. If you measure the COL with the Hornady tool like I do then you're measuring the TIP to BASE of the case. That's giving you your max COL. If that is longer than your mag so be it... What's how I'm sitting in my 6mm Fat Rat (Grendel Based Wildcat). So then you measure to what your max mag length is and set your COL there based on the TIP to BASE. Nowhere does the Ogive tool come into play. The difference is your jump. Now some bullets have variance in the meplat which the A-Max should not because of the plastic tip so you're okay measuring TIP to BASE. In my case I use Berger Hybrids which have some variance so once I get the seating depth setup to mag length for the longest meplat (I measure about 20 of the bullets alone and then use the longest bullet for setup to make sure all the rounds will fit into the mag) then I switch to the ogive tool to keep an eye on the consistency of seating and also so I can setup the die again exactly the same without the meplat variance coming into the place in my setup.

For more information you may be able to use see my thread on the Fat Rat.
http://www.snipershide.com/shooting...ild-6-5-grendel-wildcat-fans-6mm-fat-rat.html

And if the 1/2 MOA accuracy is there then your jump is not an issue. If the throat wears it may become an issue but a 6.5mm 123gr bullet in that case is not gonna wear a throat like it would in a .260 Rem so I'm sure you've got a long time before you have issues. If it does become an issue you then need to try other bullets that have a longer ogive to base length. This would be the Berger Hybrid or their BTHP bullets. Stay away from VDL bullets as it will normally require more jump. It doesn't look like they make a Hybrid in the 6.5 that's light, but they do make a 120gr BTHP. You can get a box and get a measurement and see what the jump is like. Sierra also makes a 120gr BTHP MatchKing that would be worth a look. You may find something that works better. Also look at the Brian Litz book for the real BC of all these bullets so you get an Apples to Apples comparison on BC and you're not sold false information from the manufacturer.

 

[WildBill3/75]

The A-max does....I get a variation of up to 3 thou between COAL in loaded rounds seating with my forster ultra seater. OGIVE is more accurate to measure off of if you can.

 

[Fried Chicken Blowout]

The A-max does....I get a variation of up to 3 thou between COAL in loaded rounds seating with my forster ultra seater. OGIVE is more accurate to measure off of if you can.

That's too bad, I stand corrected. Was hoping the A-Max was better than a raw meplat. Yes the ogive is more accurate, but when you have to make sure it fits in the mag the focus should be on the real COL of the round to ensure that they don't end up too long to fit. Once you establish that then the ogive measurement will be the most accurate to tell you the true jump but it's a moot point really if you're confined to mag length, your jump is what it is and as long as all your rounds are consistent that's as good as you'll get.

 

[svxwilson]

I can see some slight markings, although I don't know what I am looking for. I can see some circular paters in the bullet now what Would think the rifling would look like in the bullet? This is a pic of a bullet measured out to 2.413, after running I through the gun chamber the bullet has been set back to 2.4085. I will post more pics f the before and after of the bullet.

 

[svxwilson]

Under a flashlight you it makes it a lot easier to spot the lands and the rifling.grooves in the bullet. I believe that is what the rotational spiral grooves are...... What are your thoughts? It appears to me that the bullet is getting jammed into the rifling at this length which would prove my measurements being off???

 

[LRRPF52]

I would go to the most impartial person and ask them about this matter directly. Her name is Your Groups. If Your Groups say that jump is an issue, then listen to her...she won't pull any punches.

2.275" is where I am touching the lands with the 123gr A-MAX in my AA Grendel, and I have also seen some slight variation in the A-MAX ogive profile, but not enough to be an issue with the Grendel unless you push way out there.

Load a dummy round to 2.275" and see if it will chamber and extract without getting stuck. The mags won't let you load much longer than that anyway. If it jams into the lands hard, set it back until it doesn't, then back off a little more to compensate for ogive variation with the 123gr A-MAX, or whatever bullet you're using.