Okay, thanks for the clarification. I had assumed that there was maybe powder thay is more efficient in shorter platforms. I think i will start with H4895 though and go from there.
- Thread starter alamo5000
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What Yondering said. Just start lower than 28 gr. Your personal barrel and chamber with specific brass brand will affect pressure more than length. There’s lots of powders for .223. H4895 s a good one and worked well in my gun. It’s also temp stable which is important.
There’s also NATO chamber, .223, .223 Wylde etc chambers, all capable shooting.223 Rem with 77 gr bullets.
There’s also NATO chamber, .223, .223 Wylde etc chambers, all capable shooting.223 Rem with 77 gr bullets.
Maybe it should be reiterated again: rifle barrel length doesn't affect pressure, other than extremely short barrels that nobody actually uses. It's not a matter of length having less effect than other things, it doesn't affect it at all (other than the rare instance of a secondary pressure peak seen in long barrels with certain loads, but that's an uncommon exception).
Peak pressure in most rifle loads happens when the bullet is still very close to the chamber and throat, then that pressure peak drops off as the bullet travels down the barrel. So any length of the barrel beyond the point where that peak happens can't have an effect on pressure.
I agree with that 100%. Barrel length within reason as you said, has nothing to do with peak pressure.
That said I think there is more to be gained than just flash suppression via matching powder - bullet weight - barrel length.
Optimizing the area of the curve under peak pressure. Some combinations just get more done in the available time/distance pressure curve.
I don't have time to sort through it all now but I've been playing with this for a while now in a 10.5" 223W 8T.
Kind of stumbled onto the same thing @alamo5000 found with TAC.
Lever is hands down the fastest powder for 73gr + in my std 16-18" AR's. That has not been the case with this 10.5"
These were all using full 5.56 load pressures.
Just as an example 73gr eldm with 27.1 Lever is 2490 from the 10.5" whereas 25.4gr Tac is 2594. Same everything shot back to back. No swipes or ejector stamps on either. I know the Tac is only .2gr from stamps & honestly I haven't pushed the Lever hard to try getting another 100fps That Lever load in my 18" is 2885 with the 73. Only in this 10.5", Lever is under performing GRT predictions & Tac is over performing (by a lot). In the 18" Lever over performs.
Another example in the 10.5" is with 60gr Vmax. This one was the biggest eye opener.
Lever
28.6 GRT estimate 2660 & actual 2663
28.9 GRT predicts 2697 & actual 2665
It flattened out.
Tac
27.3 GRT 2587 & actual 2855
27.6 GRT 2621 & actual 2881 Per GRT I'd need 108% case full of Tac and be at 80K psi to hit 2880
I'm not 80K with that load primer pockets are GTG slight ejector stamp, but I expect that with full 5.56 loads. The brass looks comparable to factory XM193.
52gr eldm Tac is no longer the optimal choice, still good, but I can see the shift.
Tac
28.2gr i.e. 100% fill = 2956 group size 1.7" and brass is looking as bad or a little worse than XM193
Accurate 2200
24.4 = 2949 without any swipes or ejector stamps. group size .740"
Subject to change of coarse but here is were I'm currently for these SBR loads. I do still need to do a head to head TAC vs Lever for the 77-85
77-85gr Lever
55-73 Tac
55 and under Accurate 2200
Also as a bonus FYI I did try the new Hornady 62 eldm-vt's in this 10.5"
Shot like ass just as I expected. The ogive is to long for 223 so bearing surface was stuffed all the way in the neck even at 2.294. The holes were round, but about 4-5 moa. It's a shame cause .394BC at 2750 from a 10.5" would be a hell of a lot of fun if they were accurate.
I'm plenty happy with the TAC 73 eldm load shooting at or just under moa @2575. Also happy with the 52eldm load shooting under moa at 2940
Surprisingly the 53Vmax has a much better BC than the 52eldm. They kind of look like they were switched at berth. 53's and heavies are next outing for this.
So you agreed with what I said, and then disagreed with it and yourself? I think you’re confusing yourself with the GRT foolishness; frankly that system is nearly useless as your post shows.
Speaking to my original comment - the fastest load in a 16” will also be the fastest load in a 10.5”. Chopping off some of the barrel doesn’t change that. You seem to have disagreed with this but didn’t show any real numbers that prove otherwise; GRT estimates don’t hold any value IMO.
TAC and Lever are closer to each other than most people think, but if you have comparable loads with each using a certain bullet and the Lever load is faster in your 16” or 18” barrel, it’ll also be faster in the 10.5”. Moving beyond that the only thing to “optimize” for the short barrel is reducing flash and blast with different powder choices.
Having gone through this exact process a couple years ago I found EXACTLY what Yondering is saying to be true. The results of 6 months of "research" was
1. A 10.5" 556 barrel is useless. The sound, concussion, blast, and poor velocity made it useless. ESPECIALLY in the hypothetical "home defense" situation. Don't believe me? Try using one in a shoot house. I did when I thought of pitching it to my team. It required the use of a full size 7.8" can WITH ear pro to be in any way feasible. By contrast a 12.5" with 5.5" K can had better velocity, lower sound, concussion, and flash. I eventually settled on 14.5" with K can as optimal for REAL WORLD use. I value my sight and hearing ESPECIALLY in a life or death scenario when tunnel vision and a loss of situational awareness are greatly increased.
As such I load 77 grain SMK factory seconds on my Dillon by the thousand with 24.1 grains of TAC and several mags of Black Hills 50 grain TSX. Problem solved. I regularly do "run and gun" courses with a group of other guys. Some use 10.5" rifles. Their times and target scores compared to mine using my 14.5" with K can support my conclusions. I now use a 13" SCAR 17 with 7.8" can.
Edit to add: my buddy that I go with uses an 11.5" and is much faster than I am. He also wears bilateral hearing aids that he takes out and replaces with ear plugs UNDER his ear pro.
1. A 10.5" 556 barrel is useless. The sound, concussion, blast, and poor velocity made it useless. ESPECIALLY in the hypothetical "home defense" situation. Don't believe me? Try using one in a shoot house. I did when I thought of pitching it to my team. It required the use of a full size 7.8" can WITH ear pro to be in any way feasible. By contrast a 12.5" with 5.5" K can had better velocity, lower sound, concussion, and flash. I eventually settled on 14.5" with K can as optimal for REAL WORLD use. I value my sight and hearing ESPECIALLY in a life or death scenario when tunnel vision and a loss of situational awareness are greatly increased.
As such I load 77 grain SMK factory seconds on my Dillon by the thousand with 24.1 grains of TAC and several mags of Black Hills 50 grain TSX. Problem solved. I regularly do "run and gun" courses with a group of other guys. Some use 10.5" rifles. Their times and target scores compared to mine using my 14.5" with K can support my conclusions. I now use a 13" SCAR 17 with 7.8" can.
Edit to add: my buddy that I go with uses an 11.5" and is much faster than I am. He also wears bilateral hearing aids that he takes out and replaces with ear plugs UNDER his ear pro.
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