450Bushmaster.net

There have been allot of nay sayers on the other boards and thanks to you guys they are somewhat quieted. But some still linger and the main one is that the 450b has too much bolt thrust. Even Hornady's Lawyers won that argument, so much for the engineering expertise of the "High Speed Desk Guys"..

But here-in lies the thought..

Why is it ok to shoot the standard loading for the 6.5 Grendel and 6.8Spc with 50,000 and 55,000 psi respectively and the 450b has way too much bolt thrust @38,000psi-Saami Spec?.. I and I've seen reports of very reliable loadings for the 6.8 in extensively tested field trial loadings, from very reliable, really high-end techs, in the 63,000psi + arena..go figure..

I've been wondering the same thing. I've been shooting my 25 WSSM AR for a few years now. It has a 65k psi pressure limit and a significantly bigger case rim. I've had no problems.

With the factory 25 WSSM ammo there is mild primer flattening and a trace of the ejector on the case after firing. I've loaded my 25-06 to quite a bit hotter than this as far as pressure signs, but it's a bolt action medium-heavy barrel. So I feel a little more comfortable nearing the edge.

With my 25 WSSM reloads, the primer is a touch flatter, although I've always wondered if that was due to the differences in primers on the reloads. I figure I'm probably right at the factory limits or a little higher in pressure as I'm running the maximum charges and I'm reducing the OAL by a couple hundredths to get the rounds into the magazine. 2.25 vs. 2.27" recommended. It's shooting very nice where it's at, so I don't really feel the need to go any higher.

On a side note, I've followed the thread on the calguns forum for several months before springing for the 450. I couldn't decide weather to get the 450 or the 458. The 450 won out because of the information on that thread. I haven't been able to find the continuation of that thread on this forum. Specifically, some of your work on the hotter loads and the bolt thrust issues.

Justin -- is your 25 wssm from Dtech in MN?

No, I looked at that one but they were running far behind when I got mine.

I went with the Olympic Arms upper on a DPMS lower. The threw in their SUM barrel at no extra charge.

I like it. It's a very nice deer/antelope gun. Recoil is nice. Only drawback is that with the 24" bull barrel--kind of heavy.

Wildcatter -- how is bolt thrust calculated?

Siringo wrote:Wildcatter -- how is bolt thrust calculated?

Let's see, 2+2+2=??? Because, the neat little formulas that usually work do not work for us and the little formulas are not so little and is very difficult to display here, but I would if you really want to be impressed, with something that will not work. And Bernoulli's Therm only points us in the right direction, but will give us major clues as to why we are successful, when the Nay-Sayers tell us the we are breaking bolts (sic).

So, I actually do a mechanical measurement, with copper crushers, that I had to invent, because they don't exist for this endeavor, or recently I'm using a Pressure Film product, that has to be sent off for mega-bucks of interpretation.

Here's something to think about. These cases came out of my Mod. 450 Bushmaster. Single shot only. Manual chambering and unloading. Sooting around the case mouth in normal. Sooting down the side indicates the case is not sealing to the chamber due to low pressure. This is factory ammo and the action of the gun has nothing to do with it. Here's the pic!

You know, What with all the "bolt trust" that a straight wall case develops I guess all the .454 Casulls in the world lock the cylinder right up tight after the first shot.
BD

BD1 wrote:You know, What with all the "bolt trust" that a straight wall case develops I guess all the .454 Casulls in the world lock the cylinder right up tight after the first shot.
BD

Yeah, and the 460 Smiths, with their maximum average pressure of 65,000psi, just all of a sudden quit functioning too, go figure..t

My .284 win loads did that for the first 2 loadings. After that everything fit nice and snug and no carbon on the outside of the case. If it is doing it on new factory loads it sounds like the chamber is a tad bit larger than it needs to be or their factory brass is a tad bit small.

They must have been worried about getting one stuck and overcompensated. Played it to safe and kept the pressure down.