New AR 6.5 Grendel Problems

[gungate]

I just tested about 50 rounds. I put each one in the chamber and closed the bolt to see if it chambered correctly. Results were interesting! I have 2 cases that I reloaded in that batch. Cases that were used once and cases that were brand new. All of the new cases (double star) chamber fine but most (all?) of the used cases don't. The couple I ran through my resizer then chamber properly. I think when I resized the resizing die was not doing anything.

See the pics for the Lyman cartridge checked. They both show cartridges are good but the one is not.

 

[Rocinante]

Are there still Type 1's being sold?

Yes, shockingly. It's a common problem with under-advertising/marking and builders not knowing what they're getting into. Same goes with 6.8SCP builds. Sometimes the manufacturers don't even know there IS a difference.

This came as a set from BCA. I assume they sent the right parts. How do I check?

For the barrel, look to see if the barrel says "Type II" on it. BCA advertises they use Type II. There is no other way to tell without specialized tools.
For the bolt, remove the extractor, grab a set of precision calipers, and measure the distance from the top of the lug to the bolt face itself.
A Type I will measure 0.125"/ 3.175mm
A Type II will measure 0.136"/3.454mm

For the extractor... it's best to describe with pictures:

 

[Growler215]

Glad you fixed it. Gotta move that shoulder back at least a little for semi- autos. Then the rest of the case will *usually* be sized enough.

 

[gungate]

Glad you fixed it. Gotta move that shoulder back at least a little for semi- autos. Then the rest of the case will *usually* be sized enough.

To be clear, I didn't move anything or adjust the die, I just set it properly.

 

[Growler215]

To be clear, I didn't move anything or adjust the die, I just set it properly.

When you set your FL sizing die in accordance with the manufacturer's specification, you are moving the shoulder back to below the SAAMI minimum. This ensures that your sized brass will fit in any SAAMI spec chamber. However, depending on how your chamber is cut, this may be sizing the brass more than necessary, thereby potentially shortening the brass life.
If you get a headspace comparator and measure the headspace on fired, deprimed brass (i.e. deprimed with a universal depriming die), you can then set your FL sizing die to only move the shoulder back a few thousandths, which works the brass less while still allowing it to chamber.

Lock-N-Load Cartridge Headspace Gauge 5 Bushing Kit With Body

Lock-N-Load Cartridge Headspace Gauge 5 Bushing Kit With Body by HORNADY RELOADING TOOLSThe five bushings that come with the Lock-N-Load® Headspace Comparator provide the ability to check most bottleneck cases, from 17 Rem through the belted magnums. Ackley Improved chambers use the same...

www.midsouthshooterssupply.com

 

[gungate]

When you set your FL sizing die in accordance with the manufacturer's specification, you are moving the shoulder back to below the SAAMI minimum. This ensures that your sized brass will fit in any SAAMI spec chamber. However, depending on how your chamber is cut, this may be sizing the brass more than necessary, thereby potentially shortening the brass life.
If you get a headspace comparator and measure the headspace on fired, deprimed brass (i.e. deprimed with a universal depriming die), you can then set your FL sizing die to only move the shoulder back a few thousandths, which works the brass less while still allowing it to chamber.

Lock-N-Load Cartridge Headspace Gauge 5 Bushing Kit With Body

Lock-N-Load Cartridge Headspace Gauge 5 Bushing Kit With Body by HORNADY RELOADING TOOLSThe five bushings that come with the Lock-N-Load® Headspace Comparator provide the ability to check most bottleneck cases, from 17 Rem through the belted magnums. Ackley Improved chambers use the same...

www.midsouthshooterssupply.com

I am actually a little surprised at just how precision the chamber is. Putting a sized and "fired, not sized" case next to each other, I cannot tell a difference. But it made a HUGE difference in my AR.

 

[erwos]

Either the barrel has too short of a throat (common for BCAs), your reloads are too long for the bullet profile, or you need to use a small base sizer. Choose one to three.

 

[wilcam47]

Id think if its binding up youd be able to see marks on casing or bullet if it was hitting.

 

[John from MD]

Buy come Cerrosafe and make a chamber cast. You can then measure it and see what you actually have.

CERROSAFE® CHAMBER CASTING ALLOY | Brownells

There are various products on the market which can be used to make a cast of a gun chamber. To be certain that the product we are offering you is the best and most practical, we contacted the basic manufacturer. They recommended Cerrosafe because ...

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[brianns]

When you set your FL sizing die in accordance with the manufacturer's specification, you are moving the shoulder back to below the SAAMI minimum. This ensures that your sized brass will fit in any SAAMI spec chamber. However, depending on how your chamber is cut, this may be sizing the brass more than necessary, thereby potentially shortening the brass life.
If you get a headspace comparator and measure the headspace on fired, deprimed brass (i.e. deprimed with a universal depriming die), you can then set your FL sizing die to only move the shoulder back a few thousandths, which works the brass less while still allowing it to chamber.

Lock-N-Load Cartridge Headspace Gauge 5 Bushing Kit With Body

Lock-N-Load Cartridge Headspace Gauge 5 Bushing Kit With Body by HORNADY RELOADING TOOLSThe five bushings that come with the Lock-N-Load® Headspace Comparator provide the ability to check most bottleneck cases, from 17 Rem through the belted magnums. Ackley Improved chambers use the same...

www.midsouthshooterssupply.com

This is the way.

 

[Growler215]

I am actually a little surprised at just how precision the chamber is. Putting a sized and "fired, not sized" case next to each other, I cannot tell a difference. But it made a HUGE difference in my AR.

Hard to spot a difference of a few thousandths of an inch by eye. The actual difference between the SAAMI minimum and maximum headspace for a 6.5G chamber is only .010".
It has to be a fairly narrow window to ensure rounds will chamber and the firing pin will set the primer off. If you screw your die in more than recommended, in addition to "work hardening" the brass more, the loaded cartridge will sit too far forward in the chamber, and you could get light primer strikes.

 

[gungate]

FYI: I opened a trouble ticket with BCA on this. Even though I now know what the problem is, I am leaving the ticket open to gauge response time and effort by BCA. I am disappointed so far I have received nothing from them.

 

[gungate]

I got in that comparator already. But I got some interesting results. The ones that cycle show as bad and the ones that don't cycle show as good.

This one chambers properly. It is the double star new cases I bought. It doesn't fit in the comparator the end sticks out.

This one doesn't chamber. It is the factory cases that I reloaded but didn't size correctly. It looks perfect in the comparator.

This one does chamber. It is the factory case that I tried and would not cycle then I re-sized and it did. It looks perfect in the comparator.

 

[whistlersmother]

In the first pic, looks like the bullet is not seated as deeply as second pic.

Could the bullet be catching in the comparator before the case is fully seated?

 

[gungate]

In the first pic, looks like the bullet is not seated as deeply as second pic.

Could the bullet be catching in the comparator before the case is fully seated?

Yes! The only one that fits correctly is the empty shell that I ran through the sizing die. Neither of the other 2 is correct. The instructions say that if it is level with the top of the comparator that it is a "no go".

This is the first

2nd

3rd

 

[John from MD]

My first question is, on the star cases, did you size them before loading them?

 

[gungate]

My first question is, on the star cases, did you size them before loading them?

I "think" what happened is none of the cases got sized properly. But, the double star cases were new, unfired brass. So probably sized "somewhat" properly from the factory. It is odd that they do chamber properly and allow cycling even though the comparator hates them the most.

I think my best course of action is to take ALL of my rounds apart and redo them all using my new knowledge and extra-sweet comparator.

This was my first real batch of bullets in my new reloading hobby. I will chalk it up to a good learning lesson.

I HIGHLY recommend this comparator to anyone reloading! That Lyman one is CRAP!

 

[outrider58]

Sheridan case gauges are the shit, especially for bottle-neck cartridges. They let you see where the fail occurs.

 

[gungate]

Sheridan case gauges are the shit, especially for bottle-neck cartridges. They let you see where the fail occurs.

I just bought a 6.5 creedmoor for my bil. Every reloader should have this!

 

[Growler215]

I got in that comparator already. But I got some interesting results. The ones that cycle show as bad and the ones that don't cycle show as good.

This one chambers properly. It is the double star new cases I bought. It doesn't fit in the comparator the end sticks out.

This one doesn't chamber. It is the factory cases that I reloaded but didn't size correctly. It looks perfect in the comparator.

This one does chamber. It is the factory case that I tried and would not cycle then I re-sized and it did. It looks perfect in the comparator.

That's a case gauge, not a headspace comparator.

New Starline Grendel brass is sized at the factory but it can have dings/etc, especially in the neck, from shipping/handling since it left the factory. I usual run it through my full length sizing die which is set to move the shoulder of fired cases back a few thousandths (.003"). It doesn't do any shoulder bumping on new brass, but it does straighten out the necks.

When you chambered rounds made with new brass, it is likely that the force of chambering was enough to overcome whatever was causing it to hang up in the case gauge.

The unsized/not adequately sized previously fired reload looks looks like it is near the SAAMI max chamber headspace dimension. So that's roughly what your chamber dimension is, except your chamber is slightly less because when the bolt on a semiauto unlocks there is still some pressure in the chamber, so the brass is expanded slightly longer than the chamber. Thus the need to "bump the shoulder back" at least a few thousandths for a semiauto to cycle reliably.

When you resized in accordance with the die setup instructions, you ended up near the SAAMI minimum.

So if you don't use a headspace comparator to set up your sizing die, your brass will get stretched from about SAAMI min to about SAAMI max (i.e. about 10 thousandths) every cycle. With a headspace comparator you can set it up so you are only moving the shoulder back a few thousandths from it's fired dimension every cycle. This can help extend brass life. However, these rounds may not chamber in someone else's rifle that has a shorter chamber.

Below is a picture of a headspace comparator. It is used with your calipers to make comparison measurements between fired and unfired brass headspace. Because the point where the comparator inset touches the shoulder is likely NOT exactly where official headspace is measured for a given cartridge, the actual numbers are meaningless except as a comparison. Popular headspace comparator kits are made by Hornady and Sinclair. Each kit has inserts that cover most bottleneck cartridges that are typically reloaded.