Projectile Length to Ogive

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14-05-2023, 01:35 PM
grandpamac

Projectile Length to Ogive

Greetings all,
Have been out in the shed this morning starting to get some rifles and ammo together for next seasons F Class shoots. First cab of the rank was my .223 to be used in the 300 yard shoots. Due to its 1 in 12 twist the projectile will be the Hornady 60 grain VMAX. I had a few of these on hand and had previously shot them at 200 metres with good results. A couple more boxes of them have appeared on the shelf so the crush length overall was measured. 66.35mm. Back checked the old data, 66.8mm LOA for loaded cartridges. Hmmm. Putting one of each projectile showed that the ogive was definitely further forward on the new projectiles, projectile length was the same.
To be honest I have found quite large differences between shapes of Hornady projectile in the past with the more recent having a sharper ogive further forward on the projectile. This seems to have happened over may years but still something we should check with a new batch.
Regards Grandpamac.
14-05-2023, 01:46 PM
jackson21

Quote:

Originally Posted by grandpamac

Greetings all,
Have been out in the shed this morning starting to get some rifles and ammo together for next seasons F Class shoots. First cab of the rank was my .223 to be used in the 300 yard shoots. Due to its 1 in 12 twist the projectile will be the Hornady 60 grain VMAX. I had a few of these on hand and had previously shot them at 200 metres with good results. A couple more boxes of them have appeared on the shelf so the crush length overall was measured. 66.35mm. Back checked the old data, 66.8mm LOA for loaded cartridges. Hmmm. Putting one of each projectile showed that the ogive was definitely further forward on the new projectiles, projectile length was the same.
To be honest I have found quite large differences between shapes of Hornady projectile in the past with the more recent having a sharper ogive further forward on the projectile. This seems to have happened over may years but still something we should check with a new batch.
Regards Grandpamac.

I had some 22 cal 88's that were all over the place, was scratching my head till figured out what it was? I just put it down to massive demand and some q.c issues. I'll take it on the chin with hornady due to their price being much cheaper than a seirra.
14-05-2023, 02:47 PM
zimmer

I normally expect variation to occur lot to lot. The projectiles are spewing off a lot of die lines operating side by side all at different states of wear. Also the the lot to lot variations may not always be down to die wear eg my 7mm 180gr Hybrids didn't match Berger's spec sheet. I check before starting a new lot which in my case is important for my target rifles as I load jammed.

I also try to buy as many packs of 100 of the same lot # as I can afford, which in some cases is not many.

The worst I experienced was about 15 years ago with my 6mm MK projectiles where they were so bad in a single box I had to batch them. I know a lot of target shooters batch boxes at any rate even when the quality is high.
14-05-2023, 10:01 PM
Croc

Really interested to hear the V Max 60’s are stable in a 1:12. I tried some 50 gr Barnes Varmint Grenades which are 0.853” (0.020 shorter than the V Max) at 3,000 fps and got keyholes at 25m! The JBM Ballistics stability calculator gives the V Max 1.263 (apparently 1.3 is stable) so I guess it’s on the cusp - might give it a try…
14-05-2023, 10:51 PM
Kiwi Greg

Even top end custom projectiles vary lot to lot, no surprises mass produced cheap projectiles do

Worst I had was 270 Nosler Ballistic tips, 1mm/40 thou longer for given ogive o/a measurement resulting in rounds engaging the lands & being stuck there ......good times....
15-05-2023, 09:37 AM
grandpamac

Quote:

Originally Posted by Croc

Really interested to hear the V Max 60’s are stable in a 1:12. I tried some 50 gr Barnes Varmint Grenades which are 0.853” (0.020 shorter than the V Max) at 3,000 fps and got keyholes at 25m! The JBM Ballistics stability calculator gives the V Max 1.263 (apparently 1.3 is stable) so I guess it’s on the cusp - might give it a try…

Greetings @Croc,
I couldn't find my stability calculations so went back and did them again for both my old and new projectiles. I got much the same result as you. I have previously fired the 60 grain AMAX at 200 metres and got excellent accuracy. My VSSF rifle has a 26 inch barrel but have yet to chronograph the loads but should be able to achieve around 3,100 fps, or maybe a little more. This rifle and load will only be shot at 300 yards (275 metres) so we will see how it goes in September. Our range is only 60metres above sea level which may help. I used a .223 T3 Lite last season which has an eight inch twist with the 69 grain SMK projectiles so will have that with me if it all turns to custard.
Regards Grandpamac.
19-05-2023, 12:28 PM
grandpamac

Greetings Again.
Load data is next. I have mostly used the Hodgdons load data as it lists all the powders I use but the data for the 60 grain V-MAX tops out at 23.6 grains of BM8208 for 3,057 fps and 51,700 PSI which is very low presumably for use in semi auto rifles. A quick trawl on the interweb produced Hornady data for 60 grain projectiles running up to 25.3 grains of BM8208 for 3,000 fps. Next Load data dot com was consulted which turned up loads in line with the Hornady data from a Pet Loads by Brian Pearce. These top out at 25.4 grains of BM 8208 with the Hornady 60 grain soft point for 3,148 fps!
To be honest I am a little surprised by the variation. Generally the Hodgdons data is pretty good for US cartridges. The three data sets are likely produced using Hornady or Winchester cases which have similar weights and capacities from my measurements. Hodgdon and Hornady would have used a pressure barrel likely 24 inches and Brian used a factory rifle with a 22 inch barrel. What remains is to see where my 26 inch barrelled Varmint rifle sits and the chronograph will tell me. Will get back to you when I have answers.
Regards Grandpamac.
19-05-2023, 01:10 PM
zimmer

Hi GPM I'm sitting on a can of IMR 8208 XBR. Have yet to try it.

I bought the IMR version because ADI's smallest BM8208 was 1kg whereas the IMR was a 1lb canister. Just didn't want 1kg if I wasn't happy with the results.

Will get my A into G at some stage and try it.
19-05-2023, 01:55 PM
grandpamac

Quote:

Originally Posted by zimmer

Hi GPM I'm sitting on a can of IMR 8208 XBR. Have yet to try it.

I bought the IMR version because ADI's smallest BM8208 was 1kg whereas the IMR was a 1lb canister. Just didn't want 1kg if I wasn't happy with the results.

Will get my A into G at some stage and try it.

I got the BM8208 a couple of years back as I was having trouble getting the max loads of AR2206H in the cases, even compressed. I found the old AR2206 better as it was a touch faster. BM8208 is a little faster again and a little denser so should be ideal. It has taken the F class shooting to get things under way.
GPM.