Hornady 123 gr.BTHP

[gwtx]

Anyone used any of the "Black" BTHP's or loaded any of the BTHP bullets ? My first loads grouped pretty good, but the weather has gotten a lot hotter since then, and my loads are getting hotter as well..even though I'm using arcomp which is not supposed to be too temp sensitive. My MV's are averaging around 30 fps faster than the first loads which were pretty warm already. 2550 out of an 18" bbl., now avg around 2580. I reduced powder from 28.0 to 27.7, and on to 27.4 and the avg MV is now 2540, but still throwing 2 rounds 1/2" apart, then one
1 1/2 " to spoil the group. Still good enough for hogs, but I'd like to see'em do better. I need all the help I can get in the accuracy department. Any loads, comments, advice, or thoughts much appreciated. Gary

[sundowner]

I can't really help I use H335 and get great groups using 28.7 and get the same mz as yours but it's alot cooler up here , but 2 weeks ago it was in the 90s and 70 dew point and they still grouped good out of my 18" Sanders barrel .

[tdbru]

gwtx,
for those 123gr. Hornady bullets, and considering your heat there in TX, you might consider re-working your load for H4895. i realize you may loose a few fps as that powder is really a tad slow for 123gr. bullets, but H4895 has a very low temp coefficient. just a thought.
-tdbru.

[gwtx]

Thanks sundowner, I have done a little development with 335 and the 120g GoldDots but not much. I got up to 27.5 and the groups were decent. A tad more powder might make them great. I kinda hate to use up my supplies right now during the "shortage'. I'll try some with the bthp's as time permits. Thanks for the reply/info.

[gwtx]

Thanks tdbru. I have had such good results with the ARCOMP, I hadn't thought about a different powder,,,,yet. I have H335, and sundowner's reply may be a good alternative. I also have 4895 that I have not done much loading with. I'm not a "MV chaser"
, but most of my work with the Grendel has shown the best results at higher densities. I appreciate the info/reply.

[Bobke]

GW-
Am also in TX, NW of San Antonio. Temps near 95-100 when I shoot late afternoons. Also shoot 27.4 ARC behind 123 Sierra, 123 Nosler CC or Lapua Scenars. Have found a lot of benefit to working with overall length, or more accurately, base to ogive length, for determining optimal load development. Recent work with a 20” Bartlein had best result at 2.24” OAL, where everything above 2.25 spread out rapidly. Think a lot of folks here don’t find value in working with last piece of the puzzle-‘it’s an AR, just load it to mag length’-but I’ll bet they’d be surprised of the value of a complete process.
Check some of Padom’s results over in Snipers Hide loading forums and you might change your mind. It does work.

[gwtx]

Thanks Bobke. I absolutely agree with you. I have found that Hornady factory loads are not "mag length", and that is a good length for a starting point. The factory SST and ELD's shoot so good I got lulled into what you're talking about,,seat it mag length and go. I started the 123 BTHP's at 2.25. Then I went longer,,2.257, no help. It has worked well for the SST and ELD,,but they are a wee bit shorter, like 2.245 or so. You make a good point, I'll give it a try. I was trying to find out what the factory oal is for the 123 BTHP. . I'm thinking it is close to what you are using,,2.24X. I would buy a box to measure, but they are hard to find. This is the first time I have seen the temp sensitivity with the arcomp, but I am seeing it with the SST loads that I have been using for a long time?? Have you seen this?

Thank you for the info, Gary

[Bobke]

That specific factory loads work well in your rifle may be more coincidence than design. They’re made to satisfy SAAMI spec and the rifles of the general public, and not for the chamber of your rifle. Thus we handload to build load specs that work best in our specific rifles. And no two are identical, and so the process begins.
You might try measuring the base to ogive of the factory SST and ELD’s that shoot well in your gun, and duplicate the BTO measurement with the 123 BTHP and see if that provides any guidance. The ogival shape and measurements of SST, ELD and BTHP may not be identical and may need to be worked up independently. You probably want to know what jump to lands is with any bullet you choose, if for no other reason to have established a baseline for same. And lot to lot BTO’s can vary quite a bit based on manufacturer. Capturing the variables is what keeps us on our toes, eh?

[gwtx]

[Quote] "You might try measuring the base to ogive of the factory SST and ELD’s that shoot well in your gun, and duplicate the BTO measurement with the 123 BTHP and see if that provides any guidance. The ogival shape and measurements of SST, ELD and BTHP may not be identical and may need to be worked up independently. You probably want to know what jump to lands is with any bullet you choose, if for no other reason to have established a baseline for same. And lot to lot BTO’s can vary quite a bit based on manufacturer."

That's what I've done. I started "Grendeling" with the 123 SST. It shot well so I found a load that shot the same poi. Did the same with the ELD-M. This Sanders barrel seems to shoot whatever I fed it very well , including the first BTHP's(3/4"grp) which I loaded the same as the SST and ELD except for the seating depth. They all three shot within 1" of each other. The SST and ELD were nearly identical. Might have been in the same hole with better shooter. What's odd is that the MV for both the SST and the BTHP have increased with the warmer weather. That's ok, but the groups have spread for the BTHP, and the SST's still group the same as they always have. It's really just for curiosity that I posted. I only shoot hogs and varmints, and tiny groups are not absolutely necessary, but I like to get all my rifles/loads to sub moa. I don't have a lot of time to experiment with different components, so if I find one that works for what I do,,,I stick with it. My primary load still uses the SST. Shoots good, kills good.
I started using base to ogive measurements a long time ago due to the variances in components, but most folks "talk" about OAL, so I usually include that when talking. My mags allow more length than I ever need so I don't worry about oal if it shoots good, and is safe. The BTHP's I have measured have been very consistent so far. The "tipped" bullets, not so good. Didn't mean to be long winded, I really don't like to type.
Thank you for your input to the forum, and this thread. Gary

[VASCAR2]

I think your AR Comp load is on the edge if not over 52,000 PSI. Speer has load data for AR Comp with 120 grain Gold Dot with a maximum charge 25.3 grains at 2418 FPS out of a 24” test barrel and universal receiver. I think Speer’s data is very conservative and they don’t list the pressure of their loads. Speer is using Federal 205 MAR primers. One other thing to consider is the 120 grain Gold Dot is a bonded core bullet and tends to show more pressure for the same powder charge than typical 120 grain cup and core bullets. The momolithic bullets tend to produce more pressure compared to cup and core bullets with the same powder charge.

The data I have list AR Comp at .77 FPS per degree of higher temperature. For example 30 degrees higher temperature equals roughly 23.1 FPS higher velocity. When I’ve chronographed Hornady 123 grain A-Max and SST out of an 18” barrel on a 75 degree day I got 2464 FPS for the A-Max and 2493 FPS for the 123 grain SST. From other info posted online 18” 6.5 Grendel Hornady Factory ammo usually average 2450-2500 FPS with 120-123 grain bullets.

From my experience Hornady factory ammo using the 123 grain A-Max and 123 grain SST tended to produce a little more velocity prior to the introduction of the 123 grain ELD-M Black ammo. Many forum members are loading around 27 grains of AR Comp with 120-125 grain bullets in the 6.5 Grendel. Each barrel is unique but I’d be hesitant shoot reloads that produced over 2500 FPS with 123 grain BTHP out of 18” barrel 6.5 Grendel AR-15.

Velocity equals pressure and the higher temperature has probably increased your velocity by the 30 FPS and AR Comp appears to gain approximately .77 FPS per degree of higher temperature. With 27.4 grain load producing 2540 FPS might be safe as it would be around 2500 FPS on a 20-30 degree cooler day and probably around 2500 FPS at 70-75/degrees.

[gwtx]

Thanks vascar. Your knowledge and experience is much appreciated. I'm going to start from scratch on the bthp's, and the gold dots when I get time. I was only looking at them to begin with as an alternative to the sst and eld-m. Those are what I use.

Thanks again, and thank you for your service as a LEO. Glad you're not active duty with all the
"mess" that's going on now. Gary

[gwtx]

Thanks to all for the comments and advice. I finally stumbled(I seem to do a lot of that these days) on a good hog load with the
123gr BTHP's . Turns out the seating depth is the same base to ogive as the ELD's I load, and very close to the SST load. So I have 3 bullets that shoot very close to the same POI with the same powder load. I started with the BTHP for a backup in case things got where I could not find the SST or ELD-M. That's really all the loads I need, or can afford to "develop".
I may try to work up a load for the 120 GoldDot when time and money allows. By the way, the BTHP load was 27.0 ARC, CCI 450 primers, starline brass(cycled 4 or 5 times) and the bullets were seated 1.660" base/ogive(according to my equipment), or approximately 2.241 oal. MV averaged 2507 on a 95 degree day with light breeze. I'm using a magnetospeed, so my MV might indicate a bit higher than a "chrony" at 10 or 15 feet from the muzzle, but not much I would think.
First 3 rds of a 4 shot group were touching, but I pulled the fourth round down 1/2 to 3/4". My eyes are not real good, and I'm using a thermal scope trying to focus on a 2" square piece of aluminum tape in bright sunlight. Not exactly a clear, sharp target....I have some more excuses if that's not enough Thanks for the help guys. Gary

[Bobke]

Nice result, and more so to find three bullets that hit near same POI. ARC has been very consistent for me in the heat, and conversely is a powder whose flame temp is a bit cooler than most other powder options for Grendel, theoretically mitigating throat erosion and promoting longer barrel life. Well done.

[gwtx]

Bobke,, thanks. It was your mention of ( "Recent work with a 20” Bartlein had best result at 2.24” OAL, where everything above 2.25 spread out rapidly.") that got me going in the right direction. I measured an OEM ELD-M with my "base to ogive" guage
, and it read 1.662. I seated a BTHP to that depth, (actually 1.660) and guess what the OAL was....2.241". This is the same thing I had done with the SST and ELD loads to start with. For some reason, this time, I just seated to 2.250 OAL or so called Mag length to start with. :confused: Thanks again for the help. Gary

[Bobke]

Thx, and that’s really the beauty of this particular forum. Everyone contributing, willing to provide an assist, with little propriety or posturing involved. Don’t do well with drama or politics, and fortunately see little of it here.

[gwtx]

Yes, great site. Glad I got into Grendel and found this forum. Good shootin/huntin to ya. Gary