Range Report: 120 TTSX AR-Comp

[Hoot]

As promised, here's a brief report for my first use of Barnes 120gr TTSX bullets, along with my favorite powder, Alliant AR-Comp. AR-Comp worked very well with the 123 Amax in terms of accuracy, but not necessarily top velocity from my 24" barrel. It also worked well with the 140gr Amax, though IMHO, that bullet is a tad heavy for this caliber. I have not tried it with bullets that fall in between those two, though there are a few good hunting candidates that do.

The 120 TTSX is a L-O-N-G bullet and getting it to fit within the constraint of 2.26 COL meant a lot of it winds up in the case. From my AA 1-fired, resized brass, I did not like how the bullet felt when seating. There was a good resistance to seating until the rearward 1/4 got through the neck and then it felt too light for my taste, the rest of the press stroke. The bullet moved the powder column up and out of the way as it seated, but none of the charges were compressed. I certainly got the impression that I could have used another half grain step or two to get the speed into the sweet zone in terms of group consistency. Oddly, despite the 123 Amax tracking closely to what QL predicted (2500-2600), these 120 TTSX went significantly slower, again casting some suspicion upon the degree of neck tension. That and the presence of some faint sooting the likes of which I have never seen with this caliber and also light ejector imprinting at the highest charge, like they were not gripping the chamber as tightly as I would have liked. Primers were rounded up until the highest charge and then ever so slightly starting to flatten. Certainly not as flattened as I have achieved with faster powders as they approached maximum charge though.

So, on to the data. Here's how the four steps performed:



Resultant groups point to the need for more speed:



I'm not sure how much more powder I can get into the case before experiencing compression, but it's certainly worth a try if I want to use these bullets with this powder. As I said in the Deer Hunting Load thread, I like AR-Comp for hunting in MN as the deer season temps can range from -15 to +50 Deg and AR-Comp is incredibly temperature stable within that range.

I have not kept current with the powders du jour like CFE 223. Perhaps it would be as good a choice in terms of temp stability and bring a little more and faster energy content to the show, when using these 120 TTSX. I confess, though I have my gut feeling about this bullet, I'm in uncharted waters with regard to what to expect from it compared to cup and core bullets.

Respectably Submitted,

Hoot

[Schwag173]

I doubt the TTSX will fail to live up to your requirements. What is the 6.5mm 120gr TTSX bullet length?

[Hoot]

I doubt the TTSX will fail to live up to your requirements. What is the 6.5mm 120gr TTSX bullet length?

According to QL, it is 1.304 inches long. Not hyper-long compared to some scenar types, but the longest bullet I've ever loaded to date in this caliber. It looks to go about a half inch down into the case. No surprise since copper weights less than lead. I tested the 100gr TTSX last spring and it performed quite well in my rig. I may have to abandon my old school mind set and consider the lighter TTSX for deer.

I had one fouling 120 TTSX round left when I was done and dumped it into a dried clay embankment. For being much harder on a bullet than stacked milk jugs of water or ballistic gel, when I dug it out, it was in amazingly good shape compared to what I've seen happen to cup and core bullets shot into that same dry, hard clay. FWIW, I don't normally use that as an expansion testing medium. Empty milk jugs are easy to come by the evening before recycling day in my neighborhood. I'm just out of them right now.

Hoot

[Drifter]

I tested the 100gr TTSX and 127gr LRX through water-filled gallon jugs at 50 yds. IIRC, the 100gr was captured in the the 5th jug, and the 127gr stopped in the 8th. Compared to TTSX bullets that I've tested in another caliber, the 6.5 mushroom didn't seem very large considering the length of the projectile. It didn't seem like the 6.5 petals peeled as far back on the bullet. In other words, the hole cut by the bullet seems relatively small, but this doesn't necessarily mean that the terminal effect is insufficient.

FWIW, the 129gr InterBond is the most impressive recovered 6.5 bullet that I've seen. It was recovered in the 5th jug. The 129gr SST was captured in the 4th, and 123gr A-max in the 3rd. Nosler 120gr BT was 5th jug.

[JASmith]

QL and Long Bullets in the Grendel

I queried the Ramshot Ballistician about a year ago when I ran across the same phenomenon -- QL velocities and pressures higher than reasonable, raising safety concerns. The recipe I was stumbling on happened to use a Ramshot powder, so he was the right person to ask.

Evidently QL does not have an algorithm to model the early kick given by the primer when the base is close to it. In effect the case volume is larger than the nominal value because the bullet is further out and moving when the main charge ignites.

He suggested a couple of techniques for getting close to the right answer. I tried them and got better results, but did not feel comfortable with the "knob twisting" needed if I were to go into unknown load territory. The bullet already moving further complicates things because the rate of expansion is different than the QL math thinks it is.

For me, then, I use QL when I can get a reasonable verification of pressure and velocity predicitions, but don't count on it when I see differences of more than 50 -75 ft/sec from the calibration loads.

[Hoot]

I queried the Ramshot Ballistician about a year ago when I ran across the same phenomenon -- QL velocities and pressures higher than reasonable, raising safety concerns. The recipe I was stumbling on happened to use a Ramshot powder, so he was the right person to ask.

Evidently QL does not have an algorithm to model the early kick given by the primer when the base is close to it. In effect the case volume is larger than the nominal value because the bullet is further out and moving when the main charge ignites.

He suggested a couple of techniques for getting close to the right answer. I tried them and got better results, but did not feel comfortable with the "knob twisting" needed if I were to go into unknown load territory. The bullet already moving further complicates things because the rate of expansion is different than the QL math thinks it is.

For me, then, I use QL when I can get a reasonable verification of pressure and velocity predicitions, but don't count on it when I see differences of more than 50 -75 ft/sec from the calibration loads.

I have yet to experience a reload based upon QL's prediction that came out hotter than predicted. It seems like Helmut does not trust people to err on the side of caution and start out low and work up. So in the interest of CYA, he builds it into his algorithms whether we want it or not. I too spoke with a gentleman in the industry, more knowledgeable than me and he also passed along a few QL tweaks, which when applied, bring the actual results closer. By and large, I'm content to use the defaults, do my first field test and then massage the parameters to get it to scale properly for my setup. IIRC, Chris Long said that as long as you stay within 5% of of those defaults, you would not in effect be recreating the particular caliber outside of what it should be. Stacking tolerances being what they are, common sense dictates that if you tweak too many parameters even <5%, you can probably still steer the caliber out of what it characteristically should be, so I try to keep my fingers off the knobs as much as possible.

Given the variation in lots of cartridge brass, runs of powder, even die dimensions, I somehow doubt that there is any other way to sell folks a piece of software that could get them in so much trouble if it were wrong, and still be able to sleep at night.

Drifter, I have heard other folks speak highly of the 129 Interbond's effectiveness on deer and it is on my to-do list of bullets to test in the 6.5G. I must say that I'm surprised that the 120gr NBT, which shoots very well in my rig, penetrated as many jugs as you saw. I was under the impression that they were more explosive than that. You didn't say how long your test barrel is, or the velocity that you used for the penetration tests. I'm fairly certain that velocity would be an important factor from the experiments I've done with jugs of water. The Barnes XPB in my 450 Bushmaster goes from total expansion and stpping in 4-5 jugs to zero expansion and passing through all 8 of them, over a speed change from a 25 yard distance velocity of 2350fps to a 200 yard velocity that is down 700 fps. A testimony to the "sea anchor" effect of expansion.

It's early and the range down the road does not open until noon on Sundays, so I'm headed down to the lab to see if I can get the neck tension up a little. I'm hoping it may allow the charges to get cooking a little more before they start down the barrel, but not be so great as to cause case buckling. Looking back over my range notes from yesterday as I am typing this, I realized I did not mention an important fact that three of the five 26.5gr loads I shot, short stroked and I shot all four load ranges round robin, so I can't blame the gun. Short stroking is always worthy of concern and unacceptable for a hunting gun to say the least. I'm still not comfortable at how easy the bullets slid into the cases once the heel area cleared the bottom of the neck. I mic'd a few bullets and they appear to be sized parallel their entire length, so the jury's still out on that one.

Hoot

[JASmith]

Hoot,

Excellent points -- they expanded my appreciation of QuickLoad.

Thanks!

[BjornF16]

It's early and the range down the road does not open until noon on Sundays, so I'm headed down to the lab to see if I can get the neck tension up a little. I'm hoping it may allow the charges to get cooking a little more before they start down the barrel, but not be so great as to cause case buckling. Looking back over my range notes from yesterday as I am typing this, I realized I did not mention an important fact that three of the five 26.5gr loads I shot, short stroked and I shot all four load ranges round robin, so I can't blame the gun. Short stroking is always worthy of concern and unacceptable for a hunting gun to say the least. I'm still not comfortable at how easy the bullets slid into the cases once the heel area cleared the bottom of the neck. I mic'd a few bullets and they appear to be sized parallel their entire length, so the jury's still out on that one.

Hoot, I've been waiting for a good 120 TTSX load to be published here for some time. I attempted a couple of years ago and was getting consistent short stroking. I had considered crimping but never got around to it; found good success with 129SST and just stuck with it. I had been using both AA2230 and AA2520 with CCI 450 primers.

I wonder if using the 120 GMX with its two grooves would have better results than the TTSX with its four grooves?

[Hoot]

Though I'm loath to do it, I just could not resist that driving band groove halfway buried into the mouth. I gave a short 3-shot run of 25-26gr loads (9 total) a light touch of the Lee Factory Crimp Die, setting the mouths into that groove. That is a technique we have used with light XPB bullets on the 450 Bushmaster. It buys back some neck tension, which is a challenge with straight walled cases and gets the powder cooking a little more before the .451 bullets head down the bore. It's not hard to control the degree with good precision. If that helps get the velocity up with these, it may be a plan. BTW, if you don't want to mod a 260 Rem Lee FCD to work with the 6.5G, you can approximate the effect by removing the decapping stem from the sizing die and carefully use it to drive the mouth into the groove.

I'll be back in a little while with some results.

Hoot

[kbarnes12]

BTW, if you don't want to mod a 260 Rem Lee FCD to work with the 6.5G, you can approximate the effect by removing the decapping stem from the sizing die and carefully use it to drive the mouth into the groove.

Lee makes a Factory Crimp Die specifically for the 6.5 Grendel that works great.

Lee 6.5 Grendel Factory Crimp Die

[BjornF16]

Lee makes a Factory Crimp Die specifically for the 6.5 Grendel that works great.

Lee 6.5 Grendel Factory Crimp Die

Yup, that's the one I have, but I haven't made use of it. I was really nervous about crimping into the band, not being sure how the pressure might spike. Looking forward to Hoot's report!

[Hoot]

Ok, back home and some improvement, but not as much as I hoped for in terms of overall velocity, but boy did it tighten up the SDs and the 26gr group is as good as it gets for my shooting capability off of front and rear bags at 100 yards. I'm no professional on the bench. I'll let the images speak for themselves.

To save you having to scroll back to the first page, I relinked yesterday's images for your perusal.

Yesterday


Today


Despite the small sample base, velocities appear to have increased 1.5%. Still far short of QL's predictions, but I'll take that as a good sign.

Yesterday


Today


While the lower two charges were still ho-hum, the 26gr load was a marked improvement, no doubt from being closer in velocity to yesterday's 26.5gr group. After the first two shots went practically inside one another, I choked when the third shot came around in the round robin.

The maddening part of the endeavor was despite no short stroking, the three load steps again had a few light ejector imprints mixed in among them. I still suspect it is from the case not rising up to pressure quick enough.

WRT the homebrew FCD die, back when I got my Grendel it was only available from Lee as a custom order. Glad they saw the light, though after I made mine and started loading this caliber, I wound up not using it until now.

So, this bullet and powder combination, while workable, appears to not be a marriage made in heaven. It can work and work well with a little fiddling, but I feel in my gut that better velocity would be achievable with a slightly faster powder. My final effort WRT this combination will be to do a water shot in the not too distant future running the 26gr load and front groove crimp.

Food for thought though. Over on the 450B forum, there is a well documented mod for taking the Lee FCD to another task. That being a stab crimp that can be applied anywhere up and down the neck, such as in the second driving band groove. In that scenario, you could drive it squarely into the entire mid groove and in theory (see my signature) increase the retentivity and possibly drive this well behaving combination to a respectable velocity level as well. That constitutes band-aiding a less than optimum pairing, but if you like experimenting, it could be rewarding. Then again, I'm betting others have already developed that exact scenario with a different powder. If you have and bookmarked your range report, please link it so that I can save on search time.

Respectably submitted,

Hoot

[BjornF16]

Hoot...any chance you could post pics of the crimp you made?

AR Comp is supposedly just a little faster than RL 15...close to AA2520. I wonder if XBR8208 would work better for 120 TTSX?

Anyone have load data for 8208 and 120 TTSX or GMX?

[LRRPF52]

Sneakyone has been doing a lot of experimenting with the 120gr GMX cut down to varying weights, with the boat tail design still retained. I would agree that with the solids and their length, they are not ideal for the Grendel unless you can run the COAL way out. The 120 TTSX at 2440fps will still get the job done out to 350yds if looking at an 1800fps impact/900 ft-lb energy threshold. I think it's better suited for .260 Rem, 6.5 CM, and cases like that where it can be run easily at 2850fps or more.

The 100gr TTSX will extend your 1800/900 threshold to about 380yds if you run it at 2700fps, so it makes sense to go with the 100gr Barnes in the Grendel.

[BjornF16]

One of the reasons I'm looking at the 120 TTSX/GMX again is for a bolt gun, where I can run the length a little longer and pressure a little higher...just need a starting point with the powders I have (CFE223, 8208XBR, AA2520, AA2230, Varget, BL-(C)2)

It would be nice to have a 110 GMX...

I am contemplating the 100 TTSX for my 14.5 Ultralight...