H 4198 pressure

[smokeless77]

What kind of pressure with, let's say 60 grains of H4198 in a 45 cal, 275 grain bullet, wit a 26" barrel, sabotless.

[rbinar]

Feb 27, 2009 15:01:13 GMT -5 smokeless77 said:

What kind of pressure with, let's say 60 grains of H4198 in a 45 cal, 275 grain bullet, wit a 26" barrel, sabotless.

To dang gum much. Who ever said such a load could be shot in 45?

A maximum amount of H4198 should be about 55 grains. I wouldn't have a heart attack if one chose a grain or even 2 more because this is a mid 40kpsi load but jumping up this amount could put you who knows where.

Not only that, it is the worse type of load because it would probably shoot better and better with more powder giving the false sense that more is better.

If you feel that your rifle is designed for full pressure charges that's fine. Rifles shoot to 60+kpsi safely but if that's the case you shouldn't have to ask where the pressure is headed you should already know. The length of the barrel does not mean anything unless you have a bullet speed and charge length to go with it.

[smokeless77]

Thanks rb, I was asking that question only cuz ,I see richards custom rifles shooting 78 grains with the same set up.

[rbinar]

Feb 27, 2009 16:39:20 GMT -5 smokeless77 said:

Thanks rb, I was asking that question only cuz ,I see richards custom rifles shooting 78 grains with the same set up.

This shows a considerable difference in our approach. The Hodgdon data shows that amount should be full pressure from a 458 Winchester. It indicates that even a slightly heavier bullet bullet could be used near this amount.

I never want to approach full magnum case pressures. I want considerable room for error. However as I stated in my first reply if you feel your rifle is a full pressure model the skies the limit. For me I don't want anything to do with the recoil from this >2800fps load for a 275 grain bullet

[smokeless77]

Thanks for the info. I hear you on the bigtime recoil.

[smokeless77]

Rb, If you were to order a custom barrel,what would you say a good safe max pressure rating would be? krieger for example says 50,000 psi with a 50% saftey factor wich makes it 75,000 psi. would that be sufficient for a 45 cal.

John

[rexxer]

Smokless77- I'm curious too on what would be rb's max recomendation on the 275.

[smokeless77]

Rex, I just don't want a huge contour barrel, that you cant pickup to go hunt with.

john

[rbinar]

Feb 27, 2009 18:00:59 GMT -5 rexxer said:

Smokless77- I'm curious too on what would be rb's max recomendation on the 275.

The limit one puts on a rifle depends on who's doing the work. Most have heard of the SAMII standard. The maximum pressure allowed for commercial cases designed to shoot from strong actions is less than 65,000psi. Many cases are limited to considerably less than that either because of the firearm or case.

Still it would be a mistake to believe that is the absolute limit for modern rifles. Many competition shooters ignore the commercial standards completely. Bench rest loads exceeding 70,000psi are not uncommon.

The above is said only to show that a well made rifle should be able to withstand considerable pressure. You'd think any rifle made on the 10ML frame could take as high as the above and more. That does not mean they should be loaded to those levels. Before one makes a lot of pressure one has to ask why?

Bench rest shooters make massive pressure because equipment wear is secondary to group size. Wearing out a few barrels is normal practice. Rifles designed to shoot cased rounds make higher pressure because it is the best way to ring all the performance out of what is many times a limited case volume.

Neither reason is valid for our use. We don't have a limited powder volume and we aren't graded in tenths of an inch though some accuracy is necessary. So making extreme pressure only lowers our margin of error which is not my preferred method.

I have long advocated about 40,000psi as a limit for sabot-ed loads. This is because in warm weather much more will often result in sabot disruption. For sabot-less shooting I often list 45,000psi as the prime level but allow anything under 50,000psi. This is because some bullets take slightly more pressure to form into the rifling.

Could higher pressure be shot safely? Yes it can. Still the consequences of that pressure can't be ignored. One is rifle wear. The barrel and all other parts take much more abuse with higher pressure. The vent liner is a prime example here. High pressures in the past have greatly reduced vent liner life. Though this may not result in failure it effects accuracy expectations and incurs higher maintenance requirements. Ignoring the extra maintenance could result in premature failure.

Another reason for not shooting higher pressure is almost any power level can be reached when shooting within the listed limits. With no case restrictions shooting more powder at a lessor limit is just as plausible as having more pressure. That means if you want to shoot that 275 grain bullet to 2800fps you can do it at reasonable pressure. The only cost is slightly more powder. Some would say more recoil as well but the differences in load hardly makes a difference.

[smokeless77]

Rb, I'am in the proscess of sending in my order to krieger. He had asked me what kind of pressure i would be making. I told him anywhere up to 50,000 psi. not noing for sure is why i started this thread for the information,so i can get moving on it.

Thank's John

[Harley]

RB, your post is just so well thoughtout. It is a fine summary and cautionary guide for everyone loading other than book loads.

Thanks.

Harley