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Old June 3, 2019, 06:15 AM   #1
ReloadKy
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question about marks on fired brass?

My 6 year old nephew got his first rifle a Remington 700 compact in 243. I loaded up some ammo for him to sight in and practice with this summer before deer season. I started off with light bullets to reduce felt recoil. I had some new hornady brass that I ran through a full length sizer before deburring / chamfer. I loaded them with 40 grains of IMR 4320 and topped it with a 55 gr ballistic silvertip. The sight in procedure went fine other than some marks on the brass. When a round was ejected from we noticed an almost elongated S shape indentation that almost went the length the of the brass. This marking was not on all pieces of brass but probably 12 out of 20 rounds. Is this a pressure sign, even though I did not have a max load?

Also, when my nephew and brother would shoot the rifle there would be visible flame / muzzle blast out of the end of the barrel. Is this due to the short barrel (20 inch) or another pressure sign?

Thanks for the help.
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Old June 3, 2019, 06:28 AM   #2
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Muzzle blast is nothing to really concerned about. Hodgdons has 40 gr as a minimum listed for a 55gr Nosler BT so the load you have is probably safe. The mark on the brass could be a scratch that occurs during ejection, or it could be something in the chamber causing it.

As far as pressure goes does the bolt have "sticky" bolt lift and is it hard to pull the fired case out? If not you're probably ok, take a loaded round and chamber it, then eject the loaded round. If the mark is there it's from ejecting or chambering and it's scratching on something, if it's only there after the case is fired its a chamber defect. Can you post a pic of the brass?
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Old June 3, 2019, 07:40 AM   #3
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Sounds like something in the chamber , I would give the rifle a good cleaning and try some clean fired cases if they can chamber . Sized cases with a smaller OD my look fine . You can try some JB Compound with a tight fitting patch to clean up the chamber . I haven't looked up the powder your using , muzzle blase seems to be burn rate maybe a faster burning rate would eliminate flash .

Chris
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Old June 3, 2019, 08:20 AM   #4
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CW380 has it... the muzzle flash is the slow powder you are using. With that 20" barrel and that light bullet, I would probably try something more along the line of IMR3031.

I would cycle some of the fired brass through the action to see if they get scratched up... it's either something in the chamber, or something scratching them during the cycle process... check the feed lips and feed ramp for buggers.
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Old June 3, 2019, 08:37 AM   #5
Jim Watson
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I never thought of 4320 as a "slow" powder. A faster powder - 3031 isn't much faster - would reduce muzzle blast but it would also reduce velocity. Maybe not enough to notice, either way. I once had a 20" 6mm, similar deal, blast and flash were substantial with any load.

S shaped indention? Got pictures?
See if an unfired round is marred.
Clean the chamber thoroughly.
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Old June 3, 2019, 10:14 AM   #6
ReloadKy
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I do not have pics of the fired cases as my nephew wanted to take his "bullets" home. The unfired brass looks fine. I am guessing you all are correct and it is something in the chamber.
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Old June 3, 2019, 11:15 AM   #7
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PROBABLY something in the chamber. Usually something like a tool mark or other cut in the chamber will show on all the fired brass.

As far as muzzle blast and flash, when your burn 40gr of powder (ANY powder) in a 20" barrel, its going to have noticeable blast and flash. IMR 4320 is not a "slow" rifle powder. It's considered medium burn rate.

Going to a faster powder, such as IMR 3031 won't significantly change the muzzle blast, though it might change the flash a bit. Don't worry about "velocity loss", its a carbine (20") you're going to get what you get.

I have Remington 600 series carbines in .222. .243, 6mm, .308 and .350 Rem Mag. They ALL bark a bit more than longer barreled guns.
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Old June 3, 2019, 12:12 PM   #8
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You may have a thread of cotton in the chamber from an unraveled cleaning patch. .

I have had that happen a few times.

other marks don't usually do S shape - treads will
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Old June 3, 2019, 12:54 PM   #9
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Can you post a picture of the dented case? One assumes you know where the kid lives. snicker
"...Is this a pressure sign..." No. Especially when you consider that 40 grains of IMR4320 is the Start load for a 55 grain bullet. You really need to work up the load though.
You fit the stock to the kid? Even a Compact may be too long for a 6 yr old. LOP is 12 3/8" with the plastic stock.
"...due to the short barrel..." Probably more to do with the lighting conditions, but you will have more muzzle flash with a short barrel using any centre fire.
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Old June 3, 2019, 07:00 PM   #10
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Pictures please -

Go into the advanced reply screen and use the paperclip.

To trim down the image, crop it using PAINT.exe to just your subject item, then resize it. 256 color BMP format will usually drop the size down a bunch.

Seeing the marks will go a long way to diagnosis.
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Old June 3, 2019, 08:07 PM   #11
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He already said that he does not have the rifle or brass.
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Old June 3, 2019, 08:25 PM   #12
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Quote:
As far as muzzle blast and flash, when your burn 40gr of powder (ANY powder) in a 20" barrel, its going to have noticeable blast and flash. IMR 4320 is not a "slow" rifle powder. It's considered medium burn rate.

Going to a faster powder, such as IMR 3031 won't significantly change the muzzle blast, though it might change the flash a bit. Don't worry about "velocity loss", its a carbine (20") you're going to get what you get.
IMR3031 is almost the fastest 'rifle' powder in mainstream use... just below IMR4198/RL7... and then you are into 'slow' pistol powders. IMR4320 isn't a 'slow' powder, my miswording, but I feel it's marginally too slow for something like a 55grn .22 in a 20" barrel... but that's just me.
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Old June 3, 2019, 09:32 PM   #13
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IMR 4895 is one of the best choices for low pressure reduced loads in large cases.
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Old June 4, 2019, 06:33 AM   #14
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Give a good cleaning. If that dont clear it use a mop and a cordless drill and some flitz to polish the chamber a bit to take off any mild scratches or rough spots in the chamber
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Old June 4, 2019, 11:32 AM   #15
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I shoot a Remington 700 308 caliber with a 20" barrel shooting a Sierra 168gr MK over 40.8 grains of IMR 4064 with no muzzle flach .
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Old June 4, 2019, 12:14 PM   #16
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Hi ReloadKy,

a quick check with a ballistic simulation shows, the powder you're using is the reason for your surprising experiences.

{Edit: Image removed. See board rules on posting copyrighted materials.}


It is a moderate load with respect to the maximum pressures, but the muzzle pressure and the amount of unburned powder is far too high. You should try to switch to a more offensive powder and use less (e.g. Norma R123 with 25-28 gr). With 833 bar muzzle pressure, you are generating an extreme shockwave, which turns into underpressure and sucks, your possible relatively soft brass in a bit, after the bullet has left the muzzle (just guessing on this one, have it never seen happen). Also it defenitely affects accuracy in a negative fashion. The total actual efficiency energy-wise is absolutely beyond worse for that relatively powerful caliber, fast, small and light round and moderate/slow burning powder.

In other words: the powder, you're using is out-of-reach to produce an accurate (reduced) "bang" for that specific load.

Hope this helps...
Barney

Edit: in the simulation, i compare IMR4320 to Norma N201 according to http://www.adi-powders.com.au/powder-equivalents/

Last edited by BEG; June 4, 2019 at 12:52 PM.
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Old June 4, 2019, 01:08 PM   #17
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Sounds like a hair or thread, or possibly oil residue, in the chamber.

The notable flash, if not just more apparent due to the lighting conditions at the time, is likely a byproduct of the powder being out of its ideal conditions and not burning completely in the bore. A heavier bullet (and corresponding data) would reduce that. Or, if safe to increase, a heavier powder charge. (I didn't check published data - just threw the numbers into QuickLoad.)
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Old June 4, 2019, 05:19 PM   #18
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BEG,

I pulled your screenshot for two reasons. One is you did not follow the board rules on posting copyrighted material by stating you had permission to post it from the copyright holder and the other is that the image was too large for most people's screens. Please hold images down to a maximum width of 1024 pixels.


To the OP: In an exercise at dusk at Gunsite, we had a demonstration of the same cartridge fired in an 18" barrel and a 22" inch barrel. The muzzle flash difference was day and night, respectively. A huge white basketball-sized muzzle flash came from the 18" barrel and a much smaller yellow-orange fireball came from the 22" barrel. I'm sorry, but I don't recall what the load was, but probably something akin to M80 Ball. The same round was then fired in a 22" barrel with a Vortex flash hider on it and there was barely any visible flame except inside the slits of the flash hider itself.

A couple of things are at work determining the size of a fireball. One is that as pressure drops behind the bullet temperature drops proportionally and that mitigates the brightness and lowers the color temperature of the light coming off the gasses. The other is that a higher percentage of the powder has completed combustion by the time it reaches the muzzle.

To achieve that second effect in a shorter barrel, the faster burning powder will help. Indeed, the reason the new lead-free M855A1 round generates higher peak pressure than past M855 and SS109 ammunition is that a faster powder was employed to reduce muzzle flash in shorter barrel weapons like the M4, but the only way to then meet ballistic performance requirements was to put more of that faster powder into the case than may be done without exceeding the old M855 peak pressure limit. There are reports of significantly faster throat wear from using this ammo, as a result. Even flash reducing powder additions like nitrosoguanidine couldn't get the flash down far enough by itself.
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Old June 5, 2019, 02:20 AM   #19
BEG
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Unclenick,

thanks for the reaction. I've read the rules for this forum, before I posted. Unfortunately, I heavent realized, that any posted image requires a statment to be free of copyright/3rd party rights. Sorry for this again.

The tool I was using, is Gordons Reloading Tool (GRT, www.grtools.de), which is a free (non-commercial) tool. The license states: all results (images, reports, data, screenshots) generated by the tool and the tool itself (if distributed as a whole) can be used freely.

The assistance I tried to provide is based around the results of the numeric simulation which show a still very high muzzle pressure of 800+ bar and poor total actual efficiency (energy contained in the amount of powder in the used round vs. the energy actually used to accelerate the bullet until it leaves the barrel.)

With a more offensive (quicker) powder, the muzzle pressure could be dropped below a resonable 550 bar and the total actual efficiency should rise to 90% with a 100% of the powder burned in the barrel.

All of this could have been text-only in the first place, but I like the tools impressive "output" (And yes, the size was a bit big)
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Old June 5, 2019, 07:55 AM   #20
F. Guffey
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I have had some strange things happen between the chamber and case when firing. I have had cases split as thought they were hit with a shaped charge and I have had fired cases ejected with what appeared to be foreign objects that were trapped between the case and chamber.

On a few occasions I have found the powder did not seal the case neck when fired. When the case neck does not seal gas is allowed to flow between the chamber and case body. In every situation the trapped gas has caused strange artifacts on the case body. I do not want anything between the case body and chamber but air; I do not want a lot of air because I am the fan of cutting down on all that case travel. And there are factors.

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Old June 7, 2019, 01:54 AM   #21
BEG
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Sounds like a combination of brittle brass, fouling/cleaning issues and wrong powder to me. Like with everything else, you go to start from save ground here.

1. Give your rifle a thorough cleaning and do a visual inspection to the chamber and barrel especially
2. Test operation with some rounds of factory ammunition and inspect the spent cases

if everything looks alright so far then,

3. Reload the salvaged brass with your receipe of primer, powder, bullet and (possible) crimp. Return to 2.

if your experincing anything unusual like before, there is probably something wron with your primer, powder, bullet or a combination of then.

Last edited by BEG; June 7, 2019 at 02:14 AM.
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Old June 7, 2019, 04:38 PM   #22
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BEG,

If GRT has that statement, then it's OK to go ahead and post screenshots. We just have to know it's OK, so please add a sentence saying they allow the output to be posted online.

When I tried to look the software up, Google didn't find the company. Just a lot of YouTube videos. Thanks for posting the link. I'll look at a copy of it.
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