Help Me Interpret OCW results - Barnes 127 LRX and 100 TTSX

[jmjuhl]

I built my son a bolt action 6.5 Grendel for his first hunting rifle, and dad uses it too for pig population control. Impact Precision action in a Manners stock with an 18" Bartlein 8 twist barrel suppressed...I run the Hawkins flush bottom metal with their Grendel mags so I can load long. Very little recoil and great hunting cartridge for kids that punches way above its weight class.

I always ran 120gr TSXs in my AR Grendel with a 24" barrel and they level pigs but dropping back to an 18" barrel I knew I would be losing velocity. Many on here praise the 100gr TTSX's so I figured I would give them a try. I know the LRX is a long bullet for the Grendel so I measured my chamber and realized my OAL to the lands was 2.370" give or take a few thou. I ran Quickload for both bullets in an 18" barrel and it said roughly 2650 with the 100 and 2390 with the LRX so I figured I would give it a try. 90% of our shots are within 150 yards and I may take a few longer shots with it but nothing over 250-300yds. I compared ballistics between the bullets and while the 127 gives up a bit of trajectory it retains speed and energy well and assuming 1800 fps min expansion they are both good to 350-375yds which is plenty...but I would need to get 2400 or greater for the LRX to make sense.

My 338 Federal is stupid accurate with IMR 8208 so I started there with the 100gr TTSX so I hopefully wouldnt have to change powders often. Loaded from 27.7gr up to 29.5gr in 0.3gr increments. New Lapua brass, BR4 primers, OAL 2.270" which is about 50 thou jump. I kept going back and forth on if I wanted to load the LRX and waste components but I figured what the hell. I knew I needed velocity and many have had luck with CFE223 so started there with the 127's. Started with one round each at 28.5, 28.8, and 29.1 just to make sure everything was good. Quickload said max was somewhere in the 30-30.5 range so I loaded in 0.3 increments up to 30.6. Loaded in new Lapua brass, BR4 primers, OAL 2.330" which is 40 thou jump.

Velocity was as follows.

XBR/100TTSX:
27.7 2471 2477 2460 7.04
28.0 2519 2513 2496 9.74
28.3 2548 2547 2535 5.91
28.6 2565 2570 2568 2.05
28.9 2579 2600 2599 9.67
29.2 2621 2643 2629 9.09
29.5 2641 2664 2661 10.21

CFE223/127LRX:
29.1 2328
29.4 2356 2366 2357 4.50
29.7 2384 2387 2369 7.87
30.0 2410 2400 2406 4.11
30.3 2405 2418 2396 9.03
30.6 2421 2429 2424 3.30

No flattened primers or anything resembling stiff bolt lift on either load but the jump from 30 to 30.3 with CFE223 only went up 1fps on average so thinking Quickload was fairly accurate on where max was. Looks like the LRX has a decent node from 29.7-30.0gr and it was trying to form another one at 30.6gr but not really worth pursuing any further as I don't need to have primers popping on my 7yr old. Range temps were about 65 degrees when fired which is in the range of temps I would likely hunt in...may get a bit colder but not much so temp stability isn't a major concern. I know some have taken the XBR/TTSX combo up to 30gr and I might try to go a bit higher. Both targets have 1" squares for reference.

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[Koda]

I would go with 28.9 of XBR/100TTSX or 30 of CFE223/127LRX

Seems like you should be able to get more velocity out of the 100TTSX.

[grayfox]

Xbr book limit is 29.8 gr. H335 is another choice for the 100 ttsx, I show a book max of 30.4, so your 100 ttsx loads are in the right ballpark. For 18" I'd look for a node 2630-2675.
I load longer than book for the 100 ttsx (about 2.275) in order to do that (for 20-22" barrels) so I get a bit more MV but that's about where I'd expect you to be for 18". Node for 18" and Lrx 2340-2380.

Also note that your chrono tests are only for 3 rounds, so they are a beginning guide but the sd's won't mean much, the sample population is too small. I do that sometimes too but use the results only as a starting guide, to see how my can of powder, and my barrel, react to the loads, as each barrel is different.

I have not loaded nor shot the lrx, but again with an 18" barrel don't know I would even try it. Maybe as a cns load.
Another option is 90 gr TNT, which is a popular pig bullet, see all the videos on here by DNS and buddies. If it's hard to find then Nosler has a 90 gr Varmegeddon (even their "seconds" on shooters pro shop), the 90's at grendel velocities work even though they are considered "varmint" pills.

Saami max for the Grendel is 52 ksi, using QL you have some issues that can prevent accurate models, chiefly for the small-volume/fat body cartridges, QL has trouble without some significant tweaks. If you haven't done these/don't know about them you're probably not getting the accuracy you need. I had to adjust the sebert factor and use a larger than "saami" volume to make Grt workable, but only as a rough guide.
Using a bolt action rifle? then there is some room at the top of the pressure limits since Saami is based on not overstressing the lugs of an AR bolt/chamber. Not a big bunch however.

Finally, Barnes lists min expansion data but it is for tests in water, tests or actuals in flesh will need more MV; so for the 100 ttsx I use ~2150 as my practical limit, with 2000 as an absolute bottom floor.

Anyway, several pointers/suggestions for you to consider.

ps, if you don't have to use lead free (Tx right?), consider either 100 gr Eldm's (now available) or the 129 Ablr, which opens up down to 1300 ft/sec. the 100 eldm will give you some more MV and range to work with, and Ablr would give longer ranges.

[jmjuhl]

I would go with 28.9 of XBR/100TTSX or 30 of CFE223/127LRX
Seems like you should be able to get more velocity out of the 100TTSX.

I think I am going to run the 30.0 CFE223/127LRX for this season. I have H335 which may burn better in a short barrel and could possibly take the XBR combo up another few tenths to around 30. Even if I gain another 50-60fps with the 100gr its not buying me much in performance on the 127 @2405fps

Also note that your chrono tests are only for 3 rounds, so they are a beginning guide but the sd's won't mean much, the sample population is too small. I do that sometimes too but use the results only as a starting guide, to see how my can of powder, and my barrel, react to the loads, as each barrel is different.

That is a fair point but my sample size would need to be 30 or greater to be considered statistically significant. 3 shot SD is a weak data point but I would venture that the trend would be likely continue 95% of the time. With component availability these days I stick with 3 shot groups for hunting rifles.

ps, if you don't have to use lead free (Tx right?), consider either 100 gr Eldm's (now available) or the 129 Ablr, which opens up down to 1300 ft/sec. the 100 eldm will give you some more MV and range to work with, and Ablr would give longer ranges.

I am in Texas and dont have to have lead free...I have just used Barnes for years as they have performed really well for me. I like the ABLR bullets but unfortunately so does everyone else so they haven't been available and I like to build loads around more available components if possible (same reason I won't touch RL26 in other calibers)...plus the lower expansion velocity wont buy much as that benefit would be far above my intended hunting distance.

[Scrape hunter]

Jmju what is the case capacity of your lapua Brass?

[jmjuhl]

Jmju what is the case capacity of your lapua Brass?

I don't know. They were new unfired Lapua cases. I need to measure one now that its fire formed.