.300 BLK 163-gr problem & Sheridan slotted gauge

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Morne
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.300 BLK 163-gr problem & Sheridan slotted gauge

Post by Morne »

So I was having some problems with a new loading for my 300 blackout. I tried a 163 grain bullet and had all kinds of problems chambering them even though they were well under the maximum cartridge overall length. I bought a Sheridan slotted gauge and found the problem very easily. See pictures below:


Image here it is not fitting in the gauge

Image bullet seems to hit lands too early

Image bullet sits fine this way and measure .307" diameter

Image my normal copper plated flat point load fits fine

Image flat point fits fine here

Image flat point bullet fits similarly this way

Image my resized brass fits great

Image sized brass fine this way, too

Image bullet on far right

I think I made a mistake seating to the cannelure, here, even though it met max COAL. I think I'll disassemble these and try seating them deeper. Or should I just push them in as is until it fits?

Thoughts?
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by JustaShooter »

Since it looks like you've crimped the case mouth into the cannelure, if you try to seat the bullet deeper you'll possibly damage the brass. I might try one and see how it goes, knowing I might sacrifice that piece of brass in the process. If it goes well, once you've found the right seating depth you could try the other rounds... Sure would be easier than disassembling them if it works.
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Morne
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by Morne »

JustaShooter wrote:Since it looks like you've crimped the case mouth into the cannelure, if you try to seat the bullet deeper you'll possibly damage the brass. I might try one and see how it goes, knowing I might sacrifice that piece of brass in the process. If it goes well, once you've found the right seating depth you could try the other rounds... Sure would be easier than disassembling them if it works.
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by calvin56 »

If the bullet on the left is your old load and the one on the right is the new one and your seating both to the cannelure the right hand load has a very reduced case volume. I hope you are reducing your charge until you look for signs of overpressure.
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by JustaShooter »

Considering the bullet weights are undoubtedly very different, I'm sure Morne is doing the right ting as to powder charge.
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by Morne »

calvin56 wrote:If the bullet on the left is your old load and the one on the right is the new one and your seating both to the cannelure the right hand load has a very reduced case volume. I hope you are reducing your charge until you look for signs of overpressure.
Of the three bullets in the last picture the middle one is my normal 150-gr copper-plated flat point slug. It has no cannelure and I load it to about 2.005" COAL. The 163-gr slug on the far right was loaded to the cannelure and about 2.210" COAL (.050" shorter than max for .300 AAC BLK). I started over with my powder charge using the low end of published data for 160-165gr slugs. I just didn't get very far into shooting them when they didn't want to chamber.

The 163-gr slug is 0.535" longer than the 150-gr slug. Thus, by loading it to about 0.200" longer COAL that leaves about another 0.335" of the slug intruding into the case volume right now. Still, if it won't chamber then it won't chamber.

I'm not worried about ruining the brass, I have a pile of it now. :mrgreen: Thus, I will try shoving these deeper until they pass the Sheridan slotted gauge. Then, I will shoot the lowest powder charge weight load and post pics of the primer for the hive mind's analysis.

The one on the left is a 130-gr OTM barrier slug that I have yet to actually shoot. I did run my loads of these through the Sheridan slotted gauge and they fit just fine.
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by MyWifeSaidYes »

Umm...are those armor piercing bullets (black tip 163 grain)?

And, did you build your .300 BLK as a pistol?
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Morne
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by Morne »

I have a carbine in .300 AAC BLK.
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by Ring »

dont crip so heavy
are the bullets .308 or less ?
the neck with the bullet loaded needs to be less then .334
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by Morne »

Ring wrote:dont crip so heavy
are the bullets .308 or less ?
the neck with the bullet loaded needs to be less then .334
Yes, as I said in the OP they measure .307" diameter.

I have checked the neck dimension before and it is fine. Further, the resized brass drops into the guage easily and other rounds loaded do the same.

I do so enjoy crimping...
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by Morne »

Pushed them in, only ruined a handful of pieces of brass doing it.

Had to get them shorter than 2.086" or so to fit the gauge.

Will shoot and report velocities.
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Re: .300 BLK 163-gr problem & Sheridan slotted gauge

Post by JustaShooter »

Morne wrote:Pushed them in, only ruined a handful of pieces of brass doing it.

Had to get them shorter than 2.086" or so to fit the gauge.

Will shoot and report velocities.
Glad that worked out for you, and look forward to your range report.
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