Rounds Won't Chamber

[directdrive8]

Hi, All:

I am new to the Cast Boolit web-site. I have been reloading for a long time. I have been casting bullets a long time as well. That being said, I have not been reloading cast bullets for rifles, just for handguns. Therefore, I am a newbie in that regard. Any help is very much appreciated.

Got a problem with some 7mm-08 rounds I've started reloading. Luckily, I checked to make sure they would chamber before loading a bunch of them.

I took a empty brass case, lubed it, ran it through a resizing/decapping die. I then skipped priming and powder and ran the case through a Lyman "M" die to expand the case mouth. After that, I took a Lyman #287405 RNGC bullet and ran it into the seating die. The bullet itself is 1.075" in length. I seated it 0.435" into the case. That gave me an O.A.L. for the cartridge of 2.665". (for the mathematicians out there, please be advised that these numbers are just "close", not super precise.) I did not crimp the bullet.

I tried to chamber the cartridge and there was no way it would chamber in my rifle. Since I didn't crimp the case, I was able to gently tap the rear of the bolt until it was fully closed. Once that was done, I was able to chamber the round. After ejecting the cartridge, I measured it and the O.A.L. was 2.425". Just to make sure this was not an anomaly, I repeated the same sequences listed above with four more cases. All came out exactly the same. When I use jacketed bullets, I am able to load them to max O.A.L. (2.800") and they chamber at that length with no difficulty. What is going on here? What can I do about it and is it OK to shoot these with so much of the bullet in the case compressing the powder?

Thanks!

[Jaak]

The cast bullet you are using has a much rounder head than the jacketed round you seated before, therefore the pointier jacketed bullet can reach further into your barrel before it hits the rifling and stops, giving you a longer Overall Length. Because of the round almost hemispherical head of your cast bullet it makes contact with the rifling much sooner and then being pushed into the casing, giving you a much shorter Overall Length.

As long as you are not compressing powder at close to maximum charges you are fine. Remember to build the load up from minimum and not for best velocity.

[directdrive8]

Jaak:

Thanks for the info. I had a nagging suspicion that might be the problem. Is this a typical situation for cast rifle bullets? Can the throat of the chamber be reamed to accept a bullet with a rounder tip or do we just have to seat super deep with certain bullets?

[Ed_Shot]

I use once fired brass. My 308 is picky. I clean, resize/deprime, then check the empty brass in the chamber. If the bolt closes easy I check case length, expand with an M-die and check to see that the bolt closes easy on the empty case again. Haven't had a loaded round that wouldn't chamber following this procedure. I have a Lyman 308 chamber gauge but it does not guarantee "for me" that a loaded round will fit my chamber.

My recommendation: first check that your resized brass will chamber.

[directdrive8]

Ed Shot:

All my resized cases run through the action...no problemo. I think Jaak has it right and the big, fat, rounded point on these particular bullets is to blame. Thing is, I like the big, fat rounded point and I like big, fat, flat nose bullets too. That's why I am wondering if the throat in the rifle can be altered to accept that type of bullet?

[uscra112]

Yep, that boolit is full diameter almost all the way to the tip.

One constant headache in trying to shoot cast in modern cartridges designed with short necks for spitzer j-warts is that by the time you have them seated to fit the throat, the base of the boolit is below the neck, which does no good at all for the shooting.

[Jaak]

Jaak:

Thanks for the info. I had a nagging suspicion that might be the problem. Is this a typical situation for cast rifle bullets? Can the throat of the chamber be reamed to accept a bullet with a rounder tip or do we just have to seat super deep with certain bullets?

You can either get a different mold or go to your gunsmith and tell him what is going on and he can give you a quote on the cost of the job.

[Blackknight]

Before changing your chamber send Buckshot a message and check on his nose sizer dies. He can tell you what you will need, and it will take less time than a gunsmith. You might take a cast boolit and roll the nose on a hard smooth surface with another plate or such to reduce the nose diameter to get an idea on what diameter nose will fit your rifle. You can get a good fit which will go a long way to improving accuracy. The condition you have is better than having a loose nose fit.

[williamwaco]

You expanded with the M die and did not crimp.

The M die is the best available but it expands in two steps. The mouth of the case is expanded more than the neck.

There is a good chance that you are getting contact between the outside of the mouth of the case and the inside of the neck of the chamber.
Be sure to crimp at least enough to remove the expanded part of the mouth.

This is not the entire problem but may be a contributing factor.


.

[Tom Myers]

Jaak:

Thanks for the info. I had a nagging suspicion that might be the problem. Is this a typical situation for cast rifle bullets? Can the throat of the chamber be reamed to accept a bullet with a rounder tip or do we just have to seat super deep with certain bullets?

It appears that mold choice will probably go a long way toward solving your problem.

Attached are some sketches of various bullet configurations in a standardized 7mm-08 chamber.

Your chamber may not be the same but the sketches will help you visualize what is needed to make cast bullets work in standard rifle chambers.

The sketches should also emphasize the need to obtain a chamber cast or impact impression so that you know exactly what your chamber throat dimensions are then you can make an intelligent choice of a proper bullet design.

Depending upon your particular throat dimensions, the bullet dimater would probably need to be sized to fit out into the free bore portion of your throat configuration.

It appears that perhaps the old Lyman 287641 bullet may have been designed expressly for this throat design.

Hope this helps.

Click on the small images to enlarge them.

Attachment 73785

Attachment 73786

Attachment 73787

Attachment 73789

[cheetah]

Your situation might be where the 'bore rider' concept can come to play. Leaving out the accuracy arguments, a bore rider bullet has a nose diameter cast to ride on the minor diameter of the bore, is unaffected by sizing, and should slide right in to the front (full diameter) band - and the others which seal on the major diameter.. It's one way to stick heavy bullets in short cases.

[williamwaco]

It appears that mold choice will probably go a long way toward solving your problem.

Attached are some sketches of various bullet configurations in a standardized 7mm-08 chamber.

Spectacular ! ! !

What did you use to create those graphics?

[Tom Myers]

Spectacular ! ! !

What did you use to create those graphics?

The bullet graphic is constructed from bullet data stored in a database by my Precision Cast Bullet Design and Evaluation software that I design and market .

The chamber and cartridge graphics are constructed from companion software modules that are currently under construction.

The completed graphic is assembled with an Overlay module that allows positioning and measurement notation functions.

When all is finished, the setup will be marketed as an Ultimate Bullet Design Package for those that are serious about getting it right the first time.

Hopefully all will be ready before the Holidays at the end of the year.

You can check out my current Shooting and Reloading Software offerings at the Precision Software Store

[williamwaco]

The bullet graphic is constructed from bullet data stored in a database by my Precision Cast Bullet Design and Evaluation software that I design and market .

The chamber and cartridge graphics are constructed from companion software modules that are currently under construction.

The completed graphic is assembled with an Overlay module that allows positioning and measurement notation functions.

When all is finished, the setup will be marketed as an Ultimate Bullet Design Package for those that are serious about getting it right the first time.

Hopefully all will be ready before the Holidays at the end of the year.

You can check out my current Shooting and Reloading Software offerings at the Precision Software Store

I am a software developer for many years.
All database stuff, no graphics.

I am really impressed with your results.
I hope I can afford it when it is ready.

Mine is here: http://loansoftware.com