7mm STW Pressure signs

[eddywitay]

I was working up loads for my Sendero 7mm stw And encountered ejector marks and slightly flattened primers now here is the weird part the marks never got worse from the starting load all the way up to one grain over max now the bolt was never sticky on any of the loads .Could It be that there is something with the ejector ? I was using Nosler brass fed 215m primer and 160 Cutting edge MAX bullets As for powder charges I started form mild side to one grain over max and the powder I was using Reloader 25 and the seating depth was the formula that cutting edge bullets recommended it is something like brass trim to length plus .928 or something like that the reason for that formula is because there is a seal tight band that make contact with the bore before the ogive any one ever encounters a thing like this.

 

[243winxb]

Does the company that makes the Cutting Edge MAX bullet supply loading data? If not- Different Component = Different Pressure. Alliant lists 75.0gr maximum, with there bullet. Barnes list 77.0gr max. with there bullet. The design of your bullet has very little bearing surface, this should reduce pressure??

160 gr. VLD HPBT-MAX This maximum case capacity bullet is designed for single shot rifles or can be magazine fed in most long action rifles. A bore rider is incorporated in the design to ensure premature contact with the lands does not occur. COAL will be the brass trimmed to trim length + .968" bullet projection for recommended starting Seal Tite Band position. A minimum 1-10" barrel twist rate or faster is required. Real World BC of .585 was calculated using muzzle velocity of 2962fps and actual drops from 500 to 1000 yards.



Designed for maximum (MAX) speed by increased case capacity, the SealTite band is much further towards the tail of the bullet which allows the bullet to stick out of the case much further than the standard VLD HPBT STD bullets. A Bore Rider was added to prevent the bullet from contacting the lands and aids in making sure the bullet is centered in the bore. These bullets are for custom single shot rifle owners or for the individual that is willing to shoot single shot only as typically, magazines will not accept the C.O.A.L. that you will get with the bullet sticking out as far as it will be. In many instances, if a round is chambered but not fired, the bolt must be removed to remove the loaded cartridge because of the long C.O.A.L. The Driving Band length may or may not be the same as the standard VLD HPBT bullet and will be described in more detail in the individual bullet descriptions. More often than not, the Driving Band will be longer and only individuals that know their throat depth should use these bullets. Minimum throat depth will be stated in the bullet description and caution must be used to prevent excess pressure by the Driving Band contacting the lands. The bullets can be seated deeper but not deeper than having the Seal Tite band more than 1/2 the distance back in the neck of the case from the mouth to the shoulder. If you have any questions regarding reloading procedures or any other technical questions, please call or email our technical department.

http://site.cuttingedgebullets.com/pages/products

 

[eddywitay]

they told me to use sierra loading manual but I am going to call them today I will keep you posted

 

[eddywitay]

Just got off the phone with cutting edge now and they told me to seat the bullet .020 deeper in the case and try it .So I am going to load up some more with the same powder charge and brand with virgin brass and start from squar one Just have to weight for a nice day here in PA It is too hot to shoot a big gun like that so maybe some time next week

 

[243winxb]

High pressure signs would be IMO.- The ejector mark is raised, flowing into the hole.-Primer cratering, flowing back into the firing pin hole,but can be a Remington bolt with chamfered firing pin tunnel. -Gas leaking around the primer.-Loose primer pocket in 5 firings or less..-Web has expanded more that .001", some say .0001" is too much. -Hard bolt lift.- When workingl up, increasing the powder change, look for an orderly progression of muzzle velocity vs. charge weight. If muzzle velocity stops going up or actually goes down, or if it goes up too much, you have a problem. I would want to see more than 1 of these signs. Velocity is a poor way to measure pressure, but will give you useful info. Cartridge Brass-
Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard.
Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI when work hardened. Look at photos in these albums. some show very high pressures.
www.photobucket.com/joe1944usa