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Computer model - Bottomdweller - 07-16-2020
While working up my load for my howa, my chrony broke. Does someone here have one of those programs that can tell you the approximate velocity of your round? I have a HB 20 inch barrel. My load is 33.3 gr. LVR and the bullet is 123.5 gr. nosler partition. I file off the tip. Any other info necessary? I'm hoping it's mid 26 or better.
Computer model - grayfox - 07-16-2020
Your barrel is different than mine (which I have since sold btw), and from anyone elses.
that being said I wouldnt expect 2600 from a 20 hb Howa. Low 2500s is more like it.
if that were cfe (which I believe lvr is similar to), 33.anything is too hot, thats my 2cents.
my actual crony results for 30.8 of cfe in 20 hb was ~2510_ish, and a nice node . I did a few 125 partitions but not any more mv... you have to watch out for those, the base-lock design makes them behave more like a mono than a pure cup n core does.
Computer model - Bottomdweller - 07-17-2020
The base of the bullet is right at or ever so slightly just ahead of the beginning of the neck. I would not have throated the chamber for any other reason than more powder. I VERY carefully worked up this load having never done this before. I went up to 33.8 with still no warning bells. The bolt lift is normal. Primers are not cratering or flattening. The base of the cartridge measures around 2-3 thousands larger after firing. Ejection is normal. The powder charge is right close to the base of the bullet but I don't think I'm compressing it. With the balistic tips I was definitely having erratic pressures. Not so with the flatter base. There is definitely a pressure spike from 32.7ish to 33.0. At 400 yards its about 8 inches. But there is a crazy node from 33.0 to 33.5. At .1 grain increments all 6 were in 1.4 inch vertical stringing. Thanx for post. You are definitely one of the posters that has helped me with this rifle.
Computer model - jbmarshtx - 07-17-2020
Re the base of the cartridge being larger after firing. I have noticed this as well, especially when comparing fired brass from my howa to fired brass from my remington 700 chambered by a gunsmith. I don't know if this is common with mass produced rifles or not, someone else might be able to chime in.
Computer model - Lemonaid - 07-17-2020
You may find this of interest. http://forum.accurateshooter.com/threads/measuring-pressure-ring-and-case-head.3920808/
Computer model - Bottomdweller - 07-17-2020
I think I did read that. Amongst many others. I was pretty hungry for knowledge when I was doing this. I had nightmares about the bolt and bolt handle coming out the back of my head. I only did the work up with new starline brass. Only new. That way there was no mistake on marks left on the case. Or before and after measurements. I'm really happy! I just wish I knew how fast. Guess I better buck up and buy another chrony. Ahgg...I hate product research
Computer model - Lemonaid - 07-17-2020
Getting a Magnetospeed was a vast improvement, well worth the money. I wonder if a Labradar could be used on cars?