what should 300 blk brass measure with the hornady headspace comparator?

Moderators: gds, bakerjw, renegade, bamachem

Bgd
Senior Silent Operator
Posts: 149
Joined: Sun Jul 17, 2016 10:02 pm
Location: AR

what should 300 blk brass measure with the hornady headspace comparator?

Post by Bgd » Sat Apr 07, 2018 8:53 am

what should 300 blk brass measure with the hornady headspace comparator? I bought some LC converted brass and it is measuring 1.062 and this seems short to me?

Thanks
Last edited by Bgd on Sat Apr 07, 2018 9:22 am, edited 1 time in total.
NRA life member.

BulletFlight for Android
rlandry6
Silent But Deadly
Posts: 456
Joined: Sun Jan 14, 2018 7:39 pm

Re: what should 300 blk brass measure with the hornady case length gage?

Post by rlandry6 » Sat Apr 07, 2018 9:10 am

1.368 is the case length by Saami specs. My Hornady manual says 1.360 for the trim length, so you are a lot short. Are you measuring the case with calipers?
Bitter Gun Owner
Bitter Clinger
ArmedInfidel

Bgd
Senior Silent Operator
Posts: 149
Joined: Sun Jul 17, 2016 10:02 pm
Location: AR

Re: what should 300 blk brass measure with the hornady case length gage?

Post by Bgd » Sat Apr 07, 2018 9:22 am

rlandry6 wrote:1.368 is the case length by Saami specs. My Hornady manual says 1.360 for the trim length, so you are a lot short. Are you measuring the case with calipers?
I should have been more specific. it is the hornady headspace comparator that I am using. it measures to the shoulder.
NRA life member.

golfindia
Silent But Deadly
Posts: 1366
Joined: Thu Jun 20, 2013 1:16 pm

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by golfindia » Sat Apr 07, 2018 9:46 am

Measure a fired case and compare the two.

User avatar
dellet
Silent But Deadly
Posts: 6384
Joined: Fri Nov 30, 2012 1:25 pm

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by dellet » Sat Apr 07, 2018 9:59 am

In theory 1.070”-1.080”. That is SAAMI min/max.

Depending on what your shooting it out of that may be a problem. Ruger and Handi rifles have been the biggest problems with short shoulders. What primer used can also help or compound the problem, a military primer that has the anvil farther from the cup is an issue.

Generally speaking an AR is very forgiving down to about 1.055”. Bolts and single shots 1.060”. Depends on your chamber and firing pin length.

Then there’s is the accuracy issue with the case flopping around in the chamber and false pressure signs on the primer because it’s likely to back out and flatten more do to excessive headspace.

Should be safe in a good chamber, may not fire in a loose one.

Sadly plenty of factory brass is just as short, that’s where most of the failure to fire threads come from.
300 Blackout, not just for sub-sonics.

Bgd
Senior Silent Operator
Posts: 149
Joined: Sun Jul 17, 2016 10:02 pm
Location: AR

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by Bgd » Sat Apr 07, 2018 10:06 am

golfindia wrote:Measure a fired case and compare the two.
fired case range from 1.064 to 1.077 I think they don't always stretch to fill the chamber. I am firing these in an ar15.
NRA life member.

Bgd
Senior Silent Operator
Posts: 149
Joined: Sun Jul 17, 2016 10:02 pm
Location: AR

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by Bgd » Sat Apr 07, 2018 10:11 am

dellet wrote:In theory 1.070”-1.080”. That is SAAMI min/max.

Depending on what your shooting it out of that may be a problem. Ruger and Handi rifles have been the biggest problems with short shoulders. What primer used can also help or compound the problem, a military primer that has the anvil farther from the cup is an issue.

Generally speaking an AR is very forgiving down to about 1.055”. Bolts and single shots 1.060”. Depends on your chamber and firing pin length.

Then there’s is the accuracy issue with the case flopping around in the chamber and false pressure signs on the primer because it’s likely to back out and flatten more do to excessive headspace.

Should be safe in a good chamber, may not fire in a loose one.

Sadly plenty of factory brass is just as short, that’s where most of the failure to fire threads come from.
the idea of the case floping around in the chamber agravates me. i think i will convert my own brass next time. i dont understand why they sized them so short. i noticed my dies if i adjust them down all the way shove the shoulder back to far also. oh well live and learn.

Thanks!!
NRA life member.

User avatar
dellet
Silent But Deadly
Posts: 6384
Joined: Fri Nov 30, 2012 1:25 pm

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by dellet » Sat Apr 07, 2018 10:25 am

Bgd wrote:
dellet wrote:In theory 1.070”-1.080”. That is SAAMI min/max.

Depending on what your shooting it out of that may be a problem. Ruger and Handi rifles have been the biggest problems with short shoulders. What primer used can also help or compound the problem, a military primer that has the anvil farther from the cup is an issue.

Generally speaking an AR is very forgiving down to about 1.055”. Bolts and single shots 1.060”. Depends on your chamber and firing pin length.

Then there’s is the accuracy issue with the case flopping around in the chamber and false pressure signs on the primer because it’s likely to back out and flatten more do to excessive headspace.

Should be safe in a good chamber, may not fire in a loose one.

Sadly plenty of factory brass is just as short, that’s where most of the failure to fire threads come from.
the idea of the case floping around in the chamber agravates me. i think i will convert my own brass next time. i dont understand why they sized them so short. i noticed my dies if i adjust them down all the way shove the shoulder back to far also. oh well live and learn.

Thanks!!
Well worth the money. They allow you to adjust shoulder length while still maintaining die to shell holder contact.

Won’t stretch the short ones, but the second load works nice,

Your two lengths sound like a super and a sub load. For comparing to your chamber a full power load is needed, maybe bumped minimum and fired again. I use 1.075” as a starting point. The shoulder is so small on the cartridge, you can chamber it close the bolt by hand and forward assist and remeasure for crush.

https://www.midwayusa.com/product/35954 ... -remington

Image
300 Blackout, not just for sub-sonics.

Bgd
Senior Silent Operator
Posts: 149
Joined: Sun Jul 17, 2016 10:02 pm
Location: AR

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by Bgd » Sat Apr 07, 2018 10:39 am

dellet wrote:
Bgd wrote:
dellet wrote:In theory 1.070”-1.080”. That is SAAMI min/max.

Depending on what your shooting it out of that may be a problem. Ruger and Handi rifles have been the biggest problems with short shoulders. What primer used can also help or compound the problem, a military primer that has the anvil farther from the cup is an issue.

Generally speaking an AR is very forgiving down to about 1.055”. Bolts and single shots 1.060”. Depends on your chamber and firing pin length.

Then there’s is the accuracy issue with the case flopping around in the chamber and false pressure signs on the primer because it’s likely to back out and flatten more do to excessive headspace.

Should be safe in a good chamber, may not fire in a loose one.

Sadly plenty of factory brass is just as short, that’s where most of the failure to fire threads come from.
the idea of the case floping around in the chamber agravates me. i think i will convert my own brass next time. i dont understand why they sized them so short. i noticed my dies if i adjust them down all the way shove the shoulder back to far also. oh well live and learn.

Thanks!!
Well worth the money. They allow you to adjust shoulder length while still maintaining die to shell holder contact.

Won’t stretch the short ones, but the second load works nice,

Your two lengths sound like a super and a sub load. For comparing to your chamber a full power load is needed, maybe bumped minimum and fired again. I use 1.075” as a starting point. The shoulder is so small on the cartridge, you can chamber it close the bolt by hand and forward assist and remeasure for crush.

https://www.midwayusa.com/product/35954 ... -remington

Image

just ordered the shell holders. I didn't know they made them. I think they will be just the ticket. Thanks!! I still don't understand why they shoulder is getting bumped back so far. they must be having difficulty in the die making process? these shell holders should do the trick, cant wait to try them. Thanks again!!!
NRA life member.

mr.revolverguy
Senior Silent Operator
Posts: 134
Joined: Sun Dec 08, 2013 4:24 am
Contact:

Re: what should 300 blk brass measure with the hornady headspace comparator?

Post by mr.revolverguy » Sat Apr 07, 2018 1:21 pm

Though you have already ordered the case holders I believe this is worth a read as the 300blkout headspace is very important and not as forgiving as other cartridges especially if you have a Ruger American in 300blkout.

http://www.dayattherange.com/?page_id=5992

I agree with dellet though SAAMI spec states the headspace according to SAAMI spec is listed as 1.0789Min-1.0889Max as seen by the diagram in the article above.

Die setup is ultra critical I just decided to back my die out a bit, it is still in contact with the shell holder as it required very little adjustment. Following some die holder directions about cam over is junk especially with 300blkout. After firing in my rifles I make sure my case shoulders no matter the cartridge get's bumped back .002-.003. This even works for AR's.
Self Proclaimed -- The largest independent 300 Blackout reloading database.
http://www.dayattherange.com

Post Reply