77 TMK 8208 XBR load dev

[Dmr400]

So weighing in a little late here, regarding max charges for bolt guns. Until not too long ago sierras published load data was different for bolt guns and semis, showing significantly higher charges for bolt guns. I compared a pdf I have from a few years ago vs the current data they have on the website. It appears to me that they have neutered it back to the sammi 55k psi to match the semi data. Can't blame them these days, but the difference in charge weight for H4895 and varget for the 80 grain matchking (which the 77TMK is now listed with) are both over 3 grains less than they were just a few years ago. I'm guessing the old data probably went up to 62k psi, maybe more. I'll try to attach that pdf here. Personally my experience with bolt guns has been fine with loads from 5.56 data(62k psi) in this specific instance only (223 rem in a bolt gun). Im also using new starline 5.56 brass in my bolt 223 since lapua cases have been MIA, something i heard the FT/R 223 shooters have been doing successfully. Insert obligatory "every gun is different, work up slowly, don't try this at home" type statements.

 

[wind gypsy]

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I bought a couple of these to try on my Dillons for loading 223. Been using the OEM Dillon powder funnel.

I use this as well but never tried the standard dillon 223 powder funnel. In doing research before buying the dillon and accessories I saw that funnel come up a lot as a recommended upgrade to prevent powder bridging. Seems to work as the throws on the dillon seem to hang with those from my harrells benchrest powder measure when checked on the fx120.

 

[philcox]

Has anyone noticed a significant benefit of say CCI 450 over 400's?

 

[Castle Rock]

Yep, no pierced primers

 

[swavescatter]

Has anyone noticed a significant benefit of say CCI 450 over 400's?

My Tikka 223 - got best velocity with BR4's. I also had a slightly oversized neck bushing and wasn't getting the full 2 thou neck tension. A Lee factory crimp die with light crimp added almost 50fps to these...

 

[RockAndSage]

Has anyone noticed a significant benefit of say CCI 450 over 400's?

The 450s have a slightly thicker cup, as do all magnum primers, as I understand it. As @Castle Rock noted, it helps in preventing pierced primers. Other than that, the only differences I've heard of may be subject to more Fudd-lore than fact, so I'm not really sure if they're hotter, etc.

 

[Jimbee]

Has anyone noticed a significant benefit of say CCI 450 over 400's?

I just did an unscientific experiment with 400s vs 450s. I loaded 10 with each primer, 77gr midway factory second bullets with 23.5gr 8208 xbr, LC brass. The 450s had +10fps and SD of 10. 400s had a SD of 15. (Garmin chrono) I mainly tried this because the 400 primers frequently flatten. I know it's a small sample size and might not indicate much. I don't see any reason to buy 400s in the future if 450s are available.

 

[wind gypsy]

450s is just a good all around choice for SRP. Less likely to pierce primer and they are a little hotter so work well for the BR, GT, x47, creedmoors, 08s, etc.

 

[Schmo]

So weighing in a little late here, regarding max charges for bolt guns. Until not too long ago sierras published load data was different for bolt guns and semis, showing significantly higher charges for bolt guns. I compared a pdf I have from a few years ago vs the current data they have on the website. It appears to me that they have neutered it back to the sammi 55k psi to match the semi data. Can't blame them these days, but the difference in charge weight for H4895 and varget for the 80 grain matchking (which the 77TMK is now listed with) are both over 3 grains less than they were just a few years ago. I'm guessing the old data probably went up to 62k psi, maybe more. I'll try to attach that pdf here. Personally my experience with bolt guns has been fine with loads from 5.56 data(62k psi) in this specific instance only (223 rem in a bolt gun). Im also using new starline 5.56 brass in my bolt 223 since lapua cases have been MIA, something i heard the FT/R 223 shooters have been doing successfully. Insert obligatory "every gun is different, work up slowly, don't try this at home" type statements.

Thanks for that! I saved that file. I too am using Starline 5.56 brass. 5.56 specific data is non existent from several companies, as they default to standard 223. I had my 223 barrel throated to roughly .100 FB, so that allows me small gains. I wish more companies listed 5.56 specific data, but from what I’ve seen, in general, 5.56 data is 1-1.5 grs higher than 223 loads

 

[wind gypsy]

So weighing in a little late here, regarding max charges for bolt guns. Until not too long ago sierras published load data was different for bolt guns and semis, showing significantly higher charges for bolt guns. I compared a pdf I have from a few years ago vs the current data they have on the website. It appears to me that they have neutered it back to the sammi 55k psi to match the semi data. Can't blame them these days, but the difference in charge weight for H4895 and varget for the 80 grain matchking (which the 77TMK is now listed with) are both over 3 grains less than they were just a few years ago. I'm guessing the old data probably went up to 62k psi, maybe more. I'll try to attach that pdf here. Personally my experience with bolt guns has been fine with loads from 5.56 data(62k psi) in this specific instance only (223 rem in a bolt gun). Im also using new starline 5.56 brass in my bolt 223 since lapua cases have been MIA, something i heard the FT/R 223 shooters have been doing successfully. Insert obligatory "every gun is different, work up slowly, don't try this at home" type statements.

I can see why they'd want to move away from that 80 grain SMK data. There is no way it is for a SAAMI chamber if an 80 SMK is loaded to 2.550". That is over 0.100" past Jam in a Wylde chamber much less a SAAMI chamber!

 

[Schmo]

I can see why they'd want to move away from that 80 grain SMK data. There is no way it is for a SAAMI chamber if an 80 SMK is loaded to 2.550". That is over 0.100" past Jam in a Wylde chamber much less a SAAMI chamber!

You are probably correct, but I can measure later today. The 80 has a super long nose, putting the ogive a ways back on the bullet.

 

[wind gypsy]

You are probably correct, but I can measure later today. The 80 has a super long nose, putting the ogive a ways back on the bullet.

Possible i was reading data from older, non-pointed SMKs that would result in less COAL at the same jam? Still seems very long. 75 ELDs jam at less than 2.550 in a wylde chamber IIRC.

 

[Schmo]

Possible i was reading data from older, non-pointed SMKs that would result in less COAL at the same jam? Still seems very long. 75 ELDs jam at less than 2.550 in a wylde chamber IIRC.

Measured it with my Hornady OAL gauge in a standard 5.56 chamber. COAL at lands is 2.556” with the 80 SMK

 

[wind gypsy]

Measured it with my Hornady OAL gauge in a standard 5.56 chamber. COAL at lands is 2.556” with the 80 SMK

2.550" would be jammed in a SAAMI 223 chamber then since it has shorter freebore length (slightly smaller diameter too?) and steeper leade angle.

 

[Schmo]

That would be jammed in a SAAMI 223 chamber then.

You are correct. Jammed by 20 thou. But not near as much as one would think when you hear 2.550” COAL

 

[wind gypsy]

You are correct. Jammed by 20 thou. But not near as much as one would think when you hear 2.550” COAL

More than 20 thou.

 

[Schmo]

More than 20 thou.

223 Rem chamber is 25 thou FB
5.56 chamber is 50 thou FB
223 Wylde is 62 thou FB
223 Rem Match is 80 thou FB

 

[Schmo]

More than 20 thou.

30 thou

 

[wind gypsy]

223 Rem chamber is 25 thou FB
5.56 chamber is 50 thou FB
223 Wylde is 62 thou FB
223 Rem Match is 80 thou FB

Yeah, theres more to where a bullet jams than freebore length. Freebore Diameter and leade angle also make a difference.

Below is based upon reamers, not necessarily SAAMI/NATO spec. But ive seen 50-59 thou freebore spec'd for 556 NATO. More notably, look at freebore dimensions and leade angle. 556 has 2-2.5 thou wider freebore and and the leade angle is about half as steep, meaning it it'll take further past the end of the freebore until the lands are down to bullet diameter.

Maybe my math is off here - but i think at 1.5 degree angle, it'd take 15 thou in length to reduce diameter by 1 thou? So that is 30 thou added to COAL at jam for just freebore diameter with 2 thou larger freebore. Add a little more for differences in throat angle steepness.

 

[philcox]

I did a pressure test with XBR, CCI 400 and 450, Starline Rem 223 brass. 23, 23,5, 24, 24,5 ... no pressure signs, not hard bolt, no flat primers. I am gonna see what 24g w/ 450's do in a 10 round group.