I'm now a believer in heavy crimping

[TacoTaco]

All,

I took out 2 sets of development loads I've been working on this weekend. One was a 20 rnd series of swaged 350gr Hornady Interlocks, the other was a 20 round series of 300gr XTP Mags. Both were using AA1680 with Rem 7 1/2 Primers. The key difference however was in the crimp: The 350s were heavily crimped; so much so that the COAL expanded from 2.260 to 2.270 after they were crimped. The 300's however were only moderately crimped. Here's the data:

350gr Hornady Interlocks, Swaged to .4515.
7X Fired Brass, Annealed prior to loading.
2.260 COAL, 2.270 after Heavy Crimping.

38.0gr AA1680. Avg: 1756 FPS
39.0gr AA1680. Avg: 1831 FPS
40.0gr AA1680. Avg: 1849 FPS
41.0gr AA1680. Avg: 1870 FPS

300gr Hornady XTP Mag
Virgin Brass
2.065 COAL
Moderate Crimp

40.0gr AA1680 Avg: 1695 FPS
40.5gr AA1680 Avg: 1755 FPS
41.0gr AA1680 Avg: 1765 FPS
41.5gr AA1680 Avg: 1784 FPS

Now, take a look at each load with 40gr of the same powder. The heavier 350gr bullet beats the avg velocity of the 300gr bullet by over 150FPS!!! The only two differences that I see are the brass (Virgin vs 7x Fired/Annealed) and the crimp. I have no data to show what effect virgin brass would have on a load vs used brass, but I would think it would be negligable at best. Which brings us to the crimp. The 350's were crimped very, very well, while the 300's were only moderately so. So unless I'm crazy, I think I just proved to myself what I have been reading here for years: The .450 likes a heavy crimp!!

Oh, and to make this even sweeter, the 350's performed fairly well in the accuracy dept. Not 250gr FTX well, but not too bad considering they are swaged down flat nosed freight trains. See the pic below:

[Texas Sheepdawg]

.... You forgot to add the picture....
When you say "heavy crimp" are you saying the LeGendre Crimp?

[wildcatter]

.... You forgot to add the picture....
When you say "heavy crimp" are you saying the LeGendre Crimp?

You screwed up(←sorry guys, the Dawg is taking care of me, so I did an edit here, if you didn't see my accidental, risque quip, then never mind) Dawg, you meant to say that good looking, Brad Pitt Body Double, LeGendre Crimp, right?..wink

TacoTaco,

You need to check the crimps for spring-back. You can put on enough crimp, that after crimping, the case springs back and lets loose of the bullet and negates the benefits of the Crimp.

Also, the next time you go out, take a Sharpie and mark up the base of the cartridge, looking for bolt thrust.

Did you get a before/after measurement of the case expansion?

I bet you didn't have any problems, with the 350's/1680 but you'll want to look for the on-set of excessive pressure, then backing off the charge say, 3% or so. My money is, you'll run out of case capacity, before you get excessive pressures, BUT, time will tell and look for it.

Hey Taco Me Laddie, you did GOOD! You make us Proud!!

..t

[Hoot]

Nice job TT.

In the case of 1680 in our caliber, where velocity is the metric, crimp has to share the applause with weight. Had you reversed that experiment and lightly crimped the 350s vs heavy (tried that) crimped the 300s, I sincerely believe the 350s would have still won out as that weight is a better match for 1680s burn characteristics, all crimping aside. Keeping those horses in the barn until they're fired (minimizing bullet pull when chambering) relies heavily upon an effective crimp.

I am nonetheless impressed with the velocity you achieved with those swaged 350s. That's a lot of energy.

Do you have an Overall Length Gauge and case for the 450b? if so, how far are those "flat nosed, freight trains" from engaging the lands when you load them to 2.26/2.27 COL? The other questions here being esoteric, this one is important from a safety perspective.

Tiny Pic is very easy to use for uploading pictures you're already cropped, massaged, whatever and lastly resized to what you want them to be. For forums, I shoot for either 640x480 or 480x640 (if they're more vertical than horizontal). For readers who have MS Office installed, it includes Microsoft Office Picture Manager, a simple, handy image editor. My daughter is into complex image editors for her artwork. Dad however prefers KISS.

Hoot

[bushmeister]

Yeah, there are alot of variables in that equation when you change bullet weight... It would be interesting to see if you heavy vs. moderate crimped the same load and compared accuracy and velocity.

[TacoTaco]

Here's the accuracy pic. Like I said, it's not 250gr FTX accurate, but it isn't too bad.

Hoot: I don't have an overall length gauge and case for the .450...yet. However, when I noticed that my COAL increased to 2.27 after crimping, I checked to see if I was on the lands using the candle soot method. After the round was chambered, I saw no evidence that the bullet was contacting the lands.

Wildcatter: I did not do a pre-check to determine case expansion. I'll add that to my standard pre-fire checklist moving forward, as well as using a sharpie to try and detect bolt thrust.. In regards to spring back, I purposely spent the (ridiculously large sum of) cash on virgin brass, in an attempt to remove that variable from my test. Would Virgin Brass exhibit springback?? As for pressure signs, there were none--no extractor/ejector marks on the case base, no split mouths, etc.

All in all, Im tickled pink with my results, especially considering that these numbers were produced in a Carbine. That 1680 is good stuff when used with the heavies. The accuracy was decent enough, and the power....wow. Just wow. It scores a 42.2 on the TKO chart. Tough to beat that, especially with just over 1 MOA accuracy. That's 45/70 territory right there.

My next test will be using the same charges, but with only a moderate crimp per the comments above. I may also try some 325gr FTXs that I swaged down, provided I have enough time to get them loaded before the weekend.

Finally, thanks for the kind words everyone. It's appreciated!

[TacoTaco]

Oh, and Dawg: Yes, the crimp was performed using the "Brad Pit lookalike Crimp".

[Texas Sheepdawg]

Ahh! Yes, the LeGendre Crimp is awesome. I think we need to all chip in and get Tim a good spell/grammer check software package so he won't make those "oops" spellings.

[Hoot]

Thanks for the images TT. Looking at them, I'd say the 350s might like even more velocity to get them into the sweet zone. Not sure is you can achieve that safely, but perhaps WC may have already found it and can chime in. When I referred to 1680 as a "Gentle Giant" I meant it. It's slower turn on seems to make it a lot easier on the brass, at least the ones I was using. That's not saying you can't get in trouble with it. If the stock 450b had a slightly faster twist, you probably could get heavier bullet groups to tighten up a little more at lower velocities. That is all fine and good, but the truth is any of those shots would put meat on the table.

Could you measure the average bullet length after you size those 350s? In the case of the 325 Barnes Busters, which run .90 inches long, QL says that seated to 2.26 COL, you can get a maximum of 46gr of 1680 in there for a predicted velocity of 2120-2140 fps depending upon which start pressure model you use. Both start pressures yield predicted maximum pressures in excess of SAAMI, but within the generally accepted maximum limit for .284 Winchester. I must emphasize that those values are for a 325gr bullet, not a 350gr though.

Good Work there!

Hoot

[wildcatter]

Thanks for the images TT. Looking at them, I'd say the 350s might like even more velocity to get them into the sweet zone. Not sure is you can achieve that safely, but perhaps WC may have already found it and can chime in. When I referred to 1680 as a "Gentle Giant" I meant it. It's slower turn on seems to make it a lot easier on the brass, at least the ones I was using. That's not saying you can't get in trouble with it. If the stock 450b had a slightly faster twist, you probably could get heavier bullet groups to tighten up a little more at lower velocities. That is all fine and good, but the truth is any of those shots would put meat on the table.

Could you measure the average bullet length after you size those 350s? In the case of the 325 Barnes Busters, which run .90 inches long, QL says that seated to 2.26 COL, you can get a maximum of 46gr of 1680 in there for a predicted velocity of 2120-2140 fps depending upon which start pressure model you use. Both start pressures yield predicted maximum pressures in excess of SAAMI, but within the generally accepted maximum limit for .284 Winchester. I must emphasize that those values are for a 325gr bullet, not a 350gr though.

Good Work there!

Hoot

Yup, it sure seems like he can get more velocity. TT, as you up the powder weight, pay close attention to marks on the base, from bolt thrust. At 41gr, you are not reporting any and that's normal. Using a sharpie, will show the marks (Big-Time), when you finally get them, that's a sure sign to back off some powder. Also, measure the area just ahead of the Web, you can tell the spot, because that's all the further south, your sizing die sizes. Go for about .0015"+- expansion. If the case starts dropping on the mag, you've got too much pressure for that chamber (its sticking in the chamber, before it extracts). In that vain, look for the extractor marks on the inside of the rim. When you have to much pressure for that chamber, you may not be at MAX pressure yet, but you will have to back off the load, to get the gun to cycle.

You sound like an experienced Reloader, so pay attention, do your job safely and you may break 2000fps and even closer to 2100fps. I've seen 2100fps/350gr, but not all chamber will shoot to that number.

TT, you may indeed have seen benefits from the virgin brass, they are all Annealed at the factory and you may need to do that often, if you start to see spring-back from those heave crimps.

Your thrilled by this experience and you need to be, you're doing Yeomen work here and you're doing a good job. I just sized a batch of those Interlocks for Gunny and his LM. I bet he's going to see speeds over 2500fps, which is why you "Might", have room for more speed.

Hoot, as for a tighter twist, if you knew you were only going to use bullets heavier than 325gr a 16t would be the trick, but as we have so many choices the 24t was a trade-off, for the notion that everything will work well, some even much better than others (witness, sub moa w/250gr-ftx).

TT's 1.5MOA+- groups, are what, 4.5" at 300yds, considering that an adult deer chest, here in Michigan, is at least 18", for a kill zone (5" in Texas..wink), I'd diffidently say, that that would be meat on the table (to quote Hoot), like no 300wm could ever do at those ranges, with a chest shot! I might save those 350gr bullets for Elk, Moose, Bison, and the Big Bears. But at ranges of at 300yds and in, make the shot, Bang-Flop on anything in North America, the only thing left to do, is getting out your knife.

Hey, I just thought, the mean range for the 45-70, during the old buffalo days was 300yds. Keep in mind, before you get done, your going to smoke the shorts off the 45-70 GOV, that was using a 405gr lead bullet, in a 32"+- barrel and you'll beat that energy, hands-down, with a 20" barrel or even a 16 incher. The factory loads are advertised for Rem, Fed, Win, for a 300gr w/24" barrel at 1880fps!

Humm..

..t