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Old April 28, 2019, 05:40 PM   #1
Newts
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Load data with similar bullet weights

In the past I have always thought you could used Hodgdon load data for similar bullet weights given that you start low and work up.

Well, I got some Speer 130gr BTSP for my 7mm08 and decided to try some H4895. I started low and worked my way up using Hodgdon data for the 130gr bullet which is a Sierra hpbt.

I noticed the groups getting better with the higher loads and my velocity was finally getting better at the top end. Max load Hodgdon lists is 42gr. I did not have any pressure issues, so I tried 42.3gr. That was one of the best loads I had ever tried in any gun I’ve shot above .22 caliber. 3/4” first shot group at 200yd. Followed up with another 2 that ended up a little over 1 1/4”. I don’t own any bench guns, all hunting rifles, so I’ve always been impressed with MOA type groups. These are much smaller so it really made me start thinking.

I know that pressure can be there sometimes, yet not be visable until it’s really unsafe, so I decided to do some logical reasoning. I’m hoping you all will be able to tell me if my logic is sound.

When I look at what Hodgdon lists for their 139gr Hornady SP, it’s a max of 42.5gr of H4895. Which, that would mean that it seems the lighter Sierra bullet has something about it that maxed its load out lower than the heavier Hornady one.

I just happen to have both SP and BTSP 139gr Hornady bullets, so I started comparing them to the Speer one. I do not have a Sierra bullet to compare though. I figured that since weight is not what determines max load, since the heavier bullet has a greater max load, the bullet construction and bullet bearing surface of the lighter bullet also plays a big role.

If I set my calipers at .275”, which should be a bit under bore size, and mark each bullet where that measurement is, then I come up the same length of bearing surface between the 130gr and 139gr btsp’s, and the flat based 139gr SP being just about a 1/4” longer bearing surface.

So, if Hodgdon is saying they found their max with H4895 is 42.5gr with the 139gr Hornady SP, and my 130gr Speer is not only lighter but has a much shorter bearing surface, then wouldn’t my 42.3gr load with that 130gr Speer ‘probably’ be fine if I’m not seeing anything remotely close to pressure signs?

I have only gone over max in load development a few times, using load data for same weight bullets, and never found it to be more accurate than lower loads. This is a rare occasion where the upper end is really making this rifle shine. I just want to check my logic.
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Old April 28, 2019, 05:55 PM   #2
hounddawg
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Speer load data 7mm 08 130 gn load data

https://www.speer-ammo.com/downloads...ington_130.pdf

looks their max is different than Hogdons on the same powders. Use your own judgement or you could try this method to check for high pressures

http://shootersnotes.com/articles/wh...ures-too-high/

or buy a Pressure Trace

when the rubber meets the road you are the only one that makes the decision on whether a load is safe or not. If it feels wrong it probably is wrong
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Old April 28, 2019, 09:15 PM   #3
Newts
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Quote:
Originally Posted by hounddawg View Post
Speer load data 7mm 08 130 gn load data

https://www.speer-ammo.com/downloads...ington_130.pdf

looks their max is different than Hogdons on the same powders. Use your own judgement or you could try this method to check for high pressures

http://shootersnotes.com/articles/wh...ures-too-high/

or buy a Pressure Trace

when the rubber meets the road you are the only one that makes the decision on whether a load is safe or not. If it feels wrong it probably is wrong
Thanks. I got those sheets printed out, and also saw where a lot of their loads are higher in comparison, so it deffitetly makes me think my load is quite fine. It definitely doesn’t feel wrong, but never hurts to get more experienced loaders opinion.
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