223 seating stem for 77gr?

Jmccracken1214

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I’ve got a set of hornady custom dies and when I seat my 77gr tmk over 24gr of varget, it mangles the end of the bullet.

what do I need to avoid this?
 

rth1800

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Some simple but possibly unpalatable solutions would be reduced neck tension, inside neck lubrication both with possible crimp to hold bullet. Third one would be less powder.
 

260284

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H4895 got me to 3035 fps with the 75gr ELDM, NAMMO brass, and CCI450 primers. .020" off the lands is 2.49" COAL for me.
 

mcfred

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OP, for the 77TMKs at AR-15 mag-length, isn't that a heavily compressed column of powder? Are you deforming ogives because you're forcing things where there is no remaning space? Can you shake the case and hear kernals rattling around in there?

The TMK projectile is looong and I have to fuck around a LOT to get 26gr of Varget behind an un-tipped 77SMK at 2.300" OAL in fire-formed brass (bolt-gun), and that's still crunching kernals upon seating.

If there's still space, then less neck tension or annealed necks, lube or a seater with a larger bearing surface (something that touches lower on the ogive) would help.
 
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Jmccracken1214

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OP, for the 77TMKs at AR-15 mag-length, isn't that a heavily compressed column of powder? Are you deforming ogives because you're forcing things where there is no remaning space? Can you shake the case and hear kernals rattling around in there?

The TMK projectile is looong and I have to fuck around a LOT to get 26gr of Varget behind an un-tipped 77SMK at 2.300" OAL in fire-formed brass (bolt-gun), and that's still crunching kernals upon seating.

If there's still space, then less neck tension or annealed necks, lube or a seater with a larger bearing surface (something that touches lower on the ogive) would help.
It’s compressed as hell, prob part of the reason but where it’s damaging the bullet, isn’t that too high up for the stem to be?
I see lots of people running this load.
 

mcfred

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If you get consistent OALs/concentricity then it's good enough. Sure, the seater stem could be a larger diameter but a larger diameter seater won't fix the crushing of the projectile if it's compacting the powder.

Use a longer OAL, less powder or try a very tall funnel/powder drop tube to see if 24gr of powder will settle lower in the case.
 

padom

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If these 77 TMK are being seated to AR mag length then there is your cause. The bullet cant go any deeper because of the amount of powder in your case. Your running a 223 charge for a AICS bolt gun load where they are seated out way further creating more case capacity.


What you see others running means nothing. They may have a different chamber, single feeding, modded mags, etc... you need to load for your gun..
 

Jmccracken1214

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Would another powder give me similar velocity as varget without being compressed? Can’t shoot something that’s damaged when compressed. I guess I can back off a little to see where it isn’t so compressed.
 

padom

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Would another powder give me similar velocity as varget without being compressed? Can’t shoot something that’s damaged when compressed. I guess I can back off a little to see where it isn’t so compressed.
Accuracy over speed all day long. 23.2-23.6gr of 8208xbr is a well known AR precision load with 77smk. 2800 out of 20" 1:7 WOA

77 TMK are a lot longer than 77 SMK so your gonna eat up more case capacity to fit those TMK in a AR mag
 

padom

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I’ll grab a pound of 8208 then. I’m tempted to try the 70gr rdf nosler. $25 a box is nice
Shot like shit in 3 20" AR barrels I tested. Rainier UltraMatch Gen1 shilen, Kreiger and WOA. And I wasnt the only one that had these same results. There's a 70 RDF thread we all posted our results in around here somewhere.

They shot decent in a 26" bolt gun going much faster and closer to the lands. I have boxes collecting dust on the shelf.

77smk and 73 ELD are my go to bullets out of my precision AR's
 
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mcfred

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BLC-2 works well for me at AR-15 mag lengths with the 69gr and 77gr SMKs.

I had no luck with the 70gr RDFs in four separate rifles, especially at AR mag lengths. Jammed hard in the lands worked better than any jump, but still shot poorly on paper. Hell, I even tried them backwards out of desperation. Nope.
 
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308pirate

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Would another powder give me similar velocity as varget without being compressed? Can’t shoot something that’s damaged when compressed. I guess I can back off a little to see where it isn’t so compressed.
Ramshot TAC is an excellent ball powder that will definitely take up less volume in the case. Whether it will make enough room or not that's something I'm not sure of.

Are you an experienced reloader?

ETA: NRA service rifle shooters figured this out long ago. Hornady's 75 gr HPBT over 24.7 gr of Reloder 15 in Lake City cases using Rem 7 1/2 primers was my go to load for a Wylde-chambered AR.
 

padom

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I loaded from 22-23.8 in .2 increments. If I recall, 23.2 was compressed. And 23.8, I stated to get deformation of the bullet at the tip.
Well bud idk what your doing but I've loaded more than 10,000rd of 23.6gr over the years and never once was compressed. 24.0 starts to compress with AR mag length 77smk loads.

I have 2 buddies that have also been running this very load in their precision AR's, they aren't compressed. LC brass, 77smk.
 
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Jmccracken1214

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Well bud idk what your doing but I've loaded more than 10,000rd of 23.6gr over the years and never once was compressed. 24.0 starts to compress with AR mag length 77smk loads.

I have 2 buddies that have also been running this very load in their precision AR's, they aren't compressed. LC brass, 77smk.
Me either. I’m running Starline brass I’m not sure if it just has a locates capacity or not. But I have them seated to where they just barely fit in the mag. What seating die are you using?
 

padom

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Me either. I’m running Starline brass I’m not sure if it just has a locates capacity or not. But I have them seated to where they just barely fit in the mag. What seating die are you using?
So that starline may have less case capacity. I've never shot starline 223.

Forster ultra micrometer seater. All LC brass.
 

padom

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I’m also wondering if I should switch over to the non-tipped 77 grain
Ahhhhhh. There is your issue....TMK are WAY longer than SMK so you have to push them much farther down into the case to fit mag length therefore eating up more case capacity....


What mags are you using? I run ASC SS mags which allow COAL 2.31" so I can load 77 TMK out longer than a PMAG or similar.
 

Jmccracken1214

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Ahhhhhh. There is your issue....TMK are WAY longer than SMK so you have to push them much farther down into the case to fit mag length therefore eating up more case capacity....


What mags are you using? I run ASC SS mags which allow COAL 2.31" so I can load 77 TMK out longer than a PMAG or similar.
That’s what I figured. I’m using 20 round Magpul mags. Are the mags you’re using for an AR?
 

Bantam1

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I run LC brass with 23.5 of the 8208. I have loaded all the way to 24 grains with no issues. I tried the tipped SMK and never found them to do anything better than the regular SMK in my AR. You have to seat them too deeply into the case to make them mag length (regular GI aluminum 20 round mags). When I found a decent load they simply didn't do anything better for all the trouble. I don't think you can get them going fast enough to see the gain in the AR unless you have a longer barrel and single load them, or use that ASC mag Padom linked to. I may have to try some of those mags for myself...

I run both the 77 SMK and the Hornady 75 HPBT with the same 8208 charge. I get the same accuracy and virtually the same downrange results. I have used it in Lapua brass and LC. It shoots the same in both types of brass. I never tried Starline because I have thousands of LC cases to use. Some have been loaded 10+ times with no issues yet.