First wildcat. Case forming and bullet seating questions?

[PNW_Steve]

Hey Everyone,

Sometimes I am not very bright.... Ok.... Most of the time.....

I decided to take on my first "from parts" rifle build. A small adventure for me. Then I decided to make this my first venture into wildcat cartridges. It probably would have smarter to start with a cartridge that I can get factory ammo for.

But, here I am.

I am attempting to form brass for and load ".224 Grendel". As the name implies it is a 6.5 Grendel necked down to .224

I have worked through some challenges necking down to the correct size. My final bushing is .251 and my finished neck O.D. is .252. I tried seating a bulk 55gr FMJ and it fell right into the case. I tried a Hornady 75gr FMJ BT and it appeared to seat properly. By my measurements, the Hornady is .0015 larger in diameter than the bulk bullet.

I seated a Hornady 75gr in an empty case to a COAL of 2.26" and checked magazine function. Looked close. With the mags I have I will probably wand to stay below 2.25".

But...... When I tested it in the chamber of my rifle it appeared to chamber properly then eject properly but something looked off.... I measured the COAL and it was 2.145..... So I tried a second one and got the same result.

I can't imagine that I am hitting the lands that near in. I see folks running 90gr+ bullets in this cartridge. Again, I have trouble imagining an 88gr ELD being seated to a COAL of 2.145"

What am I missing here?

Thanks.

Stephen

[Kylongrifle32]

Did you try dropping the round into the chamber or did you rack it from the magazine?
Also did you crimp the bullet in place?
Bullet may be pushed back by hitting the top of the chamber during loading.

[skeettx]

Stephen
Well done on the trying

AR or Bolt?
Did you preseat in the chamber like KY asked?
What final chamber reamer was used? By you, or gunsmith, or factory?

A NEW unfired barrel may need a bit of use before the final dimensions settle in
Use some lighter loads and start shooting with the shorter length and then after
20 or 30 shots and three cleanings see what the new story it

Please let us know if the first firings open up the throat dimensions a bit.

Thanks and good luck
Mike

[Winger Ed.]

Paint the case & bullet with a sharpie, then chamber it.
It'll tell you where its hitting---or not.

[PNW_Steve]

Thanks Everyone.

To answer some questions:

I racked the action to load it.

I did mark the bullet and it came out with an number of small marks.

There is no crimp. With an neck OD of .252, a .224 bullet and .015 neck wall thickness I should have adequate neck tension to keep the bullet in place. Should......

I don't remember the chamber details. The barrel was supposed to have a detail sheet with it and it did not. I am going to call the vendor on Monday and get the details.

It is an AR.

[PNW_Steve]

My latest post disappeared....

I seated a second bullet and tried dropping it down the chamber. It did not go in all of the way. I pushed gently on the head of the case and it moved the rest of the way into the chamber. When I removed it COAL was 2.145 again.

Apparently the distance to the lands is a bit short...

[Wayne Smith]

Go to Rotometals.com or Brownells.com and buy some Cerrosafe. Do a cast of your chamber. You will answer your own questions.

[Kylongrifle32]

I would consider putting a crimp on the bullet with the round being used in an auto loader. It might not be the cause of your problem now but may be an issue later.
Just my 2 cents worth of advise.

If nothing else take one round and crimp the bullet then try hand feeding it into the chamber and extracting. Then Check the A.O.L.

[Moleman-]

Can you get a smaller bushing? Sizing the neck a few thousands smaller would get you the neck tension you need.

[BK7saum]

I agree with Moleman in that you need a 0.001" or 0.002" smaller bushing. I'm not saying you don't have short throat issues, but...I think your neck tension is too light based upon your opening post. In an autoloader, I like to have 0.002" to maybe 0.003" of neck tension and I have never needed to crimp any of my cartridges.

[PNW_Steve]

I would consider putting a crimp on the bullet with the round being used in an auto loader. It might not be the cause of your problem now but may be an issue later.
Just my 2 cents worth of advise.

If nothing else take one round and crimp the bullet then try hand feeding it into the chamber and extracting. Then Check the A.O.L.

This has turned into a substantial learning process. I had a similar thought and found that the Forester seating die does not apply any crimp like I remember my RCBS dies doing. For .223 I use a Lee FCD. Apparently the smart kids have already figured out how to do it with neck tension. I did order a .249 bushing on Saturday.

[PNW_Steve]

I would consider putting a crimp on the bullet with the round being used in an auto loader. It might not be the cause of your problem now but may be an issue later.
Just my 2 cents worth of advise.

If nothing else take one round and crimp the bullet then try hand feeding it into the chamber and extracting. Then Check the A.O.L.

This has turned into a substantial learning process. I had a similar thought and found that the Forester seating die does not apply any crimp like I remember my RCBS dies doing. For .223 I use a Lee FCD. Apparently the smart kids have already figured out how to do it with neck tension. I did order a .249 bushing on Saturday.


I just heard back from the barrel maker. Freebore= .080"

That seems a little close to me considering that many of the loads that I have seen published have included 88gr bullets loaded to 2.25" Coal.

[PNW_Steve]

Go to Rotometals.com or Brownells.com and buy some Cerrosafe. Do a cast of your chamber. You will answer your own questions.

I have some on the shelf. I have been reluctant to use it after receiving a warning to be VERY careful removing the cast as I could damage the rifling.

Thank you all for your replies. This is a new pursuit for me and has been quite a learning experience.

[Moleman-]

Since it's in an ar15 type action, if you do cerro cast the chamber, first take some plumbers putty and work it into the lugs with a wooden dowel to keep the cast from being too large a dia to remove. You can use aluminum foil or even cardboard to make a trough to pour the cerrosafe into the chamber. As far as damaging the rifling, the cerrosafe is much softer like lead. I use a tight fitting patch on a barbless jag to seal the bottom of the casting and an old one piece SS rod and a dummy round to set the depth. Follow the directions for the cerrosafe and don't be surprised if you have to tap the handle of the rod to break the casting free.

[country gent]

Measure the oal length for the bullet with a cleaning rod and tape.

Insert cleaning rod into the muzzle with to the bolt face and put s wrap of tape there. Then insert bullet into chamber and hold with a wood dowel. A dowel the length of a case will allow bolt to be closed lightly to hold insert cleaning rod to touch bullet and another wrap on tape. measure from lower edge to lower edge of tape wraps this will get you very close to what the chamber will accept. Sounds like you have a shorter throat or leade than others. This is a quick test to get started. A 8-32 set screw filled flat in the rod helps also.

[Wayne Smith]

I have some on the shelf. I have been reluctant to use it after receiving a warning to be VERY careful removing the cast as I could damage the rifling.

Thank you all for your replies. This is a new pursuit for me and has been quite a learning experience.

How are you going to damage the rifling with something that melts at boiling water temps and is vastly softer than brass? Only if you try to remove it with a steel rod, and I assume you know better than that!

[PNW_Steve]

How are you going to damage the rifling with something that melts at boiling water temps and is vastly softer than brass? Only if you try to remove it with a steel rod, and I assume you know better than that!

I don't know.

That is my concern. I cast the chamber on my 9mm PCC. I was concerned with the amount of effort it took to remove. I broke two oak dowels and finally bought a brass rod.

Being uncertain, I err on the side of caution.

I did hear from the barrel folks that the freebore is .080

[44magLeo]

If you have a gunsmith near by ask them about opening your throat to match your case with a bullet seated to the length you want.
Leo

[ulav8r]

The way for rifling to be damaged "by" a chamber cast is in the method used to push the cast out of the barrel. Using a solid rod with a chamfered end and tape or a plastic sleeve to prevent contact with the rifling will protect the rifling from damage.