Load Data: Spit-Fire TMZ, Part 2

Load Data: Spit-Fire TMZ, Part 2

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I put together a couple of loads and shot them off this weekend. First of all, I used the 240 gr XTP/Mag w/39 grs of H110 at 150 yards. Rifle was benched. I have a 4 power scope on it. The groups were very poor to say the least. 8 inches — more like a pattern. My second load was using the barnes 245 gr. Spitfire MZ. This was shot with 38 grs of Lil’gun. All charges where weight and OAL was 2.250 inch. Group at 150 yards was 5 inches high and 4 inches wide.

Lastly I had loaded up 20 rounds using the Barnes TMZ bullet with the plastic tip removed. I seated the bullets of an OAL of 2.250 inches. I started with 34 grs of Lil’gun and in .2 gr increments worked up to 38 grs. 34.0, 34.2, 34.4, ect. I fired each round and then marked the target, then fired another and so on.

As a control — I fired 5 rounds of factory and at 150 yards my group was dead center on the target and 1.5 inches in size. The rounds that I worked up all shot about 3.5 inches higher. An interesting trend developed:

1. 34.0 grs to 34.6 grs grouped into 2 inches
2. 35.4 grs to 35.8 grs grouped into 1.375 inches
3. 36.4 grs to 36.8 grs grouped into 1.375 inches
4. 37.0 grs to 37.4 grs grouped into 1.25 inches wide by .5 inches high

I had used this technique many times in high power rifles at 300 yards to narrow down testing. In most cases, the bullets in those test would string and then a powder range would group together and the string and another group. However with the 450 at 150 yards, with the exception of #1 above, all 15 shots from 35.4 grs to 38.0 grs grouped into a roughly 4 inch group! Not bad for 3 grs variation.

Next time I do this, I will load 35.6 grs, 36.6 grs and 37.2 grs and see if the accuracy is the same.

By admin on October 17, 2009 | Uncategorized | A comment?
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Load Data: Spit-Fire TMZ

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I just picked up some 250 gr. barnes bullets (the ones with the blue tip). However, because the weight to length ratio is greater than with lead bullets, I am not so sure they can be driven faster because the powder capacity has been reduced. Do you have any experience with these?

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I do not, but let’s see what we can do here. If you keep the OAL at 2.250″ how far into the case does the bullet go? I’m not familiar with that bullet, other than I’ve seen them. What is their intended purpose and at what speeds do they perform and what will happen to the bullet at say 2500fps+? If rapid expansion (maybe blowing off the pedals), with a gapping initial wound canal, followed by deep penetration of the left over solid portion is experienced, then that bullet might be a real winner? Is that a pointed bullet and what is it’s BC? It may take a call to Barnes (800-574-9200) to get all of that info.

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I think these are the ones he’s referring to: http://www.barnesbullets.com/products/muzzleloader/spit-fire-tmz/

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Yes, that is the correct bullet. Seated to 2.250 inches, the bullet is approximately 1.13 inches long. The bullet is seated into the case .58 inches. The bullet is a boatail and has approximately .4 inches of full diameter bearing surface. When seated, it is right or a little past the portion of the bullet that begins to taper. These would be used for deer hunting. Acccording to the literature, the bullet is designed for the speeds we are taling about.

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Yep, .58″ is quite deep and you’ll want to back off of the powder, bringing it slowly until the primers tell you to stop. Single load them into your weapon, with the magazine inserted, so you can see if the bolt stays open after you shoot. It sounds like the case mouth is over the ojive at the 2.250″ OAL, is that correct? This bullet is designed for magnum muzzle loader velocities, which are in the 2000fps+ area. Are you able to buy box lots of this bullet or do you have to buy them in smaller blister-packs, like the Hornady SST’s?

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Yes, the case mouth is over the ojive. I had purchased the bullets in a blister pack. For the heck of it, I pulled the blue plastic tip from the end of the bullet and that shortened the bullet by .22″, leaving a hollow point of approximately .225″ in diamter. I seated this bullet in the case to an OAL of 2.250″ They do chamber and the bullet is in the case about the same depth as the Hornady 240 XTp/Mag. Also, it appears that the bearing surface of the barnes bullet is the same as the 240 gr. I might be better off using the MZ’s instead, but I need to get some to make the measurements.

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Taking the tip off is a great tip. Now when you seat them to the 2.250″, how far into the case are they? It might have been ok to crimp over the ojive, I’ve done it. The only real problem is if there is a large enough void at the bullet/case mouth junction to pick up junk. The taper crimp would not normaly have over crimped. If you’d only have been only slightly over the ojive, you’d proably have not had any problems, as long as the head-space could be maintained, then maybe. I’ve shot 308 reloads many times in the AR. To make them fit the magazine the bullet must be seated well deep into the case and at 2.250″ OAL, the crimp was way out over the ojive. This was done with perfect success. But with the 450b head-space is another problem to ponder, if one were to try this trick with that Barnes bullet. Of course a dangerous situation could develop if you did try to do this, I’m only trying to expand the thinking here and to examine the possibilities.

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Bullet is in the case approximately .36″ when the plastic tip is removed.

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That’s perfect. Rule of thumb for all cartridges is a full caliber depth, for this cartridge that would make it .451″, into the case. I commonly use .187” with no problems (assuming the round fits the mag), but nothing less, for fear of inducing a problem.

I’m thinking this bullet will be an over-all winner, especially since you figured out the tip removal thing and a 290gr bullet can be had in this configuration too boot. Buying them in blister packs gets pricey, but box lots are probably available, if you talk to Barnes directly.

Ok, now load some of those 250’s up to a very conservative 2200fps and shoot for accuracy and I’m personally hoping you do the milk jug penetrations test (if you do five or more, then you’re good to go). You’d want to start out with a lighter load than Slash’s because you have less case volume, hence, higher pressures, or try AA1680. If you can, get some pictures of the cases and some nice close-ups of the primers with powder grain weights visible on the case side, like Slash provided, that would be very instructive. And sending a pepperroni pizza to all of us reading this would be nice too. Am I asking too much?

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