Please forgive me, I'm a bolt gunner. But, what's wrong with those primers? Apparently they made the load go "boom"?
Flatten Primers and Excessive Pressure out of Factory Hornady Amax?
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If that were my gun, I would be measuring that chamber! You could be loading too long. 30g of CFE is a light load under a 123g pill. Are all the primers from your 30g CFE loads that flat, or is it more hit and miss and you picked all the flat ones for the pic? Those primers in the 30.6g loads look really rough. I don't usually get concerned about flat primers but those are really flat for the load.Last edited by Bwild97; 11-20-2015, 09:00 PM.
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Originally posted by FW Conch View PostPlease forgive me, I'm a bolt gunner. But, what's wrong with those primers? Apparently they made the load go "boom"?
Using more precise language we are concerned because the op is concerned. Once we get more information like the velocity readings we can then have more of an idea what the peak pressure is. If above SAAMI then sooner or later one or more of the teeth of his bolt will shear. Having spent some years shooting F Class it was standard practise to load more than SAAMI to get .223 bullets to reach 1,000 and still be supersonic (and competitive). Comparing the robust, solid actions, barrels, and bolts of an F Class gun against the relatively fragile light-weight frame of an AR, including the relatively small bolts lugs which are prone to shearing is why we are concerned. Unlikely it is going to blow up in his face but flattened primers could be a sign of over-pressure. PF has mentioned in the same thread he is concerned about the sheared bolt lugs of clients recently. We've all taken note and are wondering what the pressure is inside the op's cases.
Once the velocity readings are posted we will be in a better position to compare against SAAMI. Like you imply, it may be nothing. Or, it may be over-pressure hammering his gun.
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Flat primers can also be a symptom of excessive headspace. Sequence: 1) Firing pin drives cartridge to front of chamber till shoulder makes contact 2) powder ignites and pressurizes the inside of the cartridge case 3) the primer has much less resistance than the bullet, so it is pushed reward partially out of the case until it contacts the bolt face 4) the bullet begins to move 5) the brass case stretches to fill the chamber, reseating the primer giving it a very flat appearance. Check the headspace of fired vs unfired rounds.
- PA
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30.6gr under 123gr is a very mild load, and should not be producing brass with cratered primers.
What COL are you loading to? I'm starting to suspect that you're jammed into the lands.Last edited by LRRPF52; 11-21-2015, 09:25 PM.NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
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You could still end up with bullets jammed in the lands because they can jump forward on being loaded in an auto-loading gun. If the neck tension is not enough to hold the bullet in place after coming to a violent stop it will jump forward. Sometimes this jump is enough to touch the lands and that will produce a pressure spike. Auto shooters mitigate this by paying attention to neck tension when sizing and/or using crimping.
Another possible reason for your pressure spike is that your chamber has been reamed by a worn reamer. If the diameter of the chamber at the neck is too tight to allow the brass to expand properly and release the bullet then you get a dangerous pressure spike. Whoever headspaced the chamber should have checked with gauges but, on a Friday afternoon at beer-O-clock...
There are a number of reasons why your primers are flat and more information than speculation will solve the riddle. Using the same ammo in another Grendel (if the owner is comfortable with you using it!). You can fashion a replacement skyscreen out of plastic or cardboard if you don't want to wait for a new chrono.
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Originally posted by tasty_chicken View PostI trimmed the case to 1.150" and the COAL is 2.251". If the COAL is a issue why am I seeing flattened primers with factory wolf ammo?
As for velocity I will need to buy a new chronograph. Hopefully there will be a magnetospeed on sale soon.
It's looking to me like your throat is short, since all the ammo is behaving the same. I think you're jamming the lands. This is easy to determine with a dummy cartridge or one of your factory loads. Color the ogive with a marker, place it in the chamber fully with a finger or dowel, then turn the upper barrel up to see if the cartridge will fall free on its own.
If it doesn't, carefully remove it with a coated rod or the BCG, making sure to control the ejection so it doesn't hit the barrel extension teeth.
Observe the ogive for any signs of land engagement. Report back.NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
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Originally posted by LRRPF52 View PostI think you meant 1.510" trim length?
It's looking to me like your throat is short, since all the ammo is behaving the same. I think you're jamming the lands. This is easy to determine with a dummy cartridge or one of your factory loads. Color the ogive with a marker, place it in the chamber fully with a finger or dowel, then turn the upper barrel up to see if the cartridge will fall free on its own.
If it doesn't, carefully remove it with a coated rod or the BCG, making sure to control the ejection so it doesn't hit the barrel extension teeth.
Observe the ogive for any signs of land engagement. Report back.
Just tried this with a factory 123 sst. The round falls out of the chamber with ease and the ogive of the bullet shows no signs of land engagement. I will be ordering the magnetospeed soon so when I get it I will have better results.
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So here is a update on where I am at on this. I finally got another chronograph but not the magnetospeed and here iss the velocity data. I ran 2 factory loads first just to get some baseline data. Factory Wolf Steel 100gr and Hornady 123gr SSTs. Now I tested 3 loads and these were loads that were the most accurate for my rifle. It is still not as tight as the factory Hornady 123gr SST or AMAX.
So my conclusion from the velocity data is that my rifle will just flatten primers but it isn't a indication of overpressure as show by the velocity. The velocity i'm getting is actually in line with the Hornady load manual. Below are all the pictures.
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