450Bushmaster.net

I need some help on reloading data for the Barnes 250 Grain XPB bullets and H110 for my RAR. looking to get to 2,500 fps similar to what Jeff at Gunblast is getting with his. Any info would be great!

For What cartridge are you looking for data specifically?

Ahh sorry about that. The 450 BM.

shooter75 wrote:Ahh sorry about that. The 450 BM.

Regardless of the platform, getting the 450b pushing a 250gr bullet at 2500fps requires patience and slow, methodical workup. It's not a load-n-go achievement. Assuming you have a strong reloading foundation already behind you, you can work up to a goal, but you really need some barrel length to hit that kind of velocity. Quickload puts the chamber pressure way above recommended safe level (60k psi) out of a 20" barrel to struggle to even reach 2450fps with 100% fill of H110, which it's good at predicting the performance of. That yields a 99.93 burn rate which is as good as it gets. Faster powders like Lil Gun will do better in a shorter carbine length (16") barrel but it still only reaches 2400 fps with a 100% charge while dancing with the devil at 59k psi.

I don't use a single shot or bolt action despite them being able to handle higher pressure than the original AR platform. This caliber is plenty lethal with lower velocities. Accurate too. The parent case (284 Winchester) is rated for 63k psi, so in theory (see signature) its up for the trip, but how stable is that load? Temperature factors in. Ball powders, operating in the "red zone" at one temperature, can fall over the edge when the temperature goes up. I would not attempt your goal without speaking personally with Jeff to see what magic he pulled out of his chrony getting there, but that's me.

Hoot

Thank you Hoot for the info and help!! I emailed Jeff just waiting on a response.

Keep in mind, SAAMI spec for 450 Bushmaster is 38,000 PSI. Wildcatter doesn't recommend much over even though we know the lawyers had a say in this.

Hoot wrote:

shooter75 wrote:Ahh sorry about that. The 450 BM.

Regardless of the platform, getting the 450b pushing a 250gr bullet at 2500fps requires patience and slow, methodical workup. It's not a load-n-go achievement. Assuming you have a strong reloading foundation already behind you, you can work up to a goal, but you really need some barrel length to hit that kind of velocity. Quickload puts the chamber pressure way above recommended safe level (60k psi) out of a 20" barrel to struggle to even reach 2450fps with 100% fill of H110, which it's good at predicting the performance of. That yields a 99.93 burn rate which is as good as it gets. Faster powders like Lil Gun will do better in a shorter carbine length (16") barrel but it still only reaches 2400 fps with a 100% charge while dancing with the devil at 59k psi.

I don't use a single shot or bolt action despite them being able to handle higher pressure than the original AR platform. This caliber is plenty lethal with lower velocities. Accurate too. The parent case (284 Winchester) is rated for 63k psi, so in theory (see signature) its up for the trip, but how stable is that load? Temperature factors in. Ball powders, operating in the "red zone" at one temperature, can fall over the edge when the temperature goes up. I would not attempt your goal without speaking personally with Jeff to see what magic he pulled out of his chrony getting there, but that's me.

Hoot

Hoot I know nothing about QL, but when you say 100% fill, is that mean the case topped off, or do they figure a certain depth for seating a bullet?

Al in Mi wrote:Hoot I know nothing about QL, but when you say 100% fill, is that mean the case topped off, or do they figure a certain depth for seating a bullet?

QL knows all bullet lengths as well as the average case capacity of the caliber in question and the density of the powders in its database. When you specify a COL for a load, it calculates what percentage of case capacity remains for the powder. 100% fill implies in this case that at a COL of 2.26 it is filled to the base of the bullet. With some technique you can usually get them to 105% which sounds like an oxymoron, but is achievable. I converted an electro-pencil engraver to "buzz" the case once the powder is dispensed into it. Very cool to see it settle down to reveal more room. The classic approach was to use a powder drop tube when charging the load. Basically gravity and momentum packs it down as well. Many years ago, I published a simple how-to process for modding an electro-pencil, to apply a small amount of case vibration. The key is to get one with adjustable intensity and dial it down. Otherwise the powder jumps around so much that it reintroduces space between the granules instead of packing it out. The effect is most pronounced with stick powders but ball powders benefit as well. Once again, I strayed off topic...

Hoot

Hey Hoot could you tell me if QL has the Barnes #30562 250 grain HP in their data base?? Im on the fence on getting QL.

Its pretty easy to add a new bullet to QL. A pair of calipers is all you really need to measure the bullet and add the needed dimensions. Nice to add the BC too and most of the manufactures publish that so it can be looked up. I have added dozens of bullets to my copy.