Bullet Brand/Pressure Differences?
- Thread starter antelopedundee
- Start date
Randy Jarvais
New member
Your assumption is incorrect and there lies the error.
Assuming that a safe load with a particular bullet can be transferred to another bullet is a wrong assumption. If you read the beginning sections of any handloading manual, each with clearly state that a change in ANY component that is different than what is listed in their load data, ie primer, case, powder, and yes bullet, one should decrease powder charge and start the process accordingly. I don't have a manual at hand but I seem to remember 10% less powder. I experienced a similar issue going from a custom 117 bullet to a Speer 110 or 115 grain hollow point. Much more pressure due to what I assumed was more baring surface (less pointy). The chrono will indicate by virtue of speed. If the same weight bullet in the same caliber with the same components produces more speed than another, then there was more pressure. Most of the time that extra pressure doesn't cause an issue but as others mentioned, if the pressure is near max in what someone thinks is a safe load (no difficulty with bolt lift), then the possibility exists that a change could cause a large enough spike in pressure getting the bullet started down the rifling which in turn could cause a difficult bolt lift. Just because you are not getting that situation in your experience doesn't mean it doesn't happen. Heck the other person may have gone beyond what the loading manual suggested in the first place because he wasn't having any perceived issues with ejection, so he may be overloading already (according to a manual). You may not be. Hope this helps explain what others have already said.
Assuming that a safe load with a particular bullet can be transferred to another bullet is a wrong assumption. If you read the beginning sections of any handloading manual, each with clearly state that a change in ANY component that is different than what is listed in their load data, ie primer, case, powder, and yes bullet, one should decrease powder charge and start the process accordingly. I don't have a manual at hand but I seem to remember 10% less powder. I experienced a similar issue going from a custom 117 bullet to a Speer 110 or 115 grain hollow point. Much more pressure due to what I assumed was more baring surface (less pointy). The chrono will indicate by virtue of speed. If the same weight bullet in the same caliber with the same components produces more speed than another, then there was more pressure. Most of the time that extra pressure doesn't cause an issue but as others mentioned, if the pressure is near max in what someone thinks is a safe load (no difficulty with bolt lift), then the possibility exists that a change could cause a large enough spike in pressure getting the bullet started down the rifling which in turn could cause a difficult bolt lift. Just because you are not getting that situation in your experience doesn't mean it doesn't happen. Heck the other person may have gone beyond what the loading manual suggested in the first place because he wasn't having any perceived issues with ejection, so he may be overloading already (according to a manual). You may not be. Hope this helps explain what others have already said.
Doug Casner
New member
primers
Ive read the posts 2 or 3 times. What kind of primers are you using? What did the other primers look like with the hornady and nosler bullets? Are you living on the edge? If so. Ive had Winchester primers be flat and the same load on the next one pierce and blow clear out on a 6.5 cm. I laid it on to brass cups and started loading a half a lighter charge and changed to cci. Should o loaded the same charge with the cci primers and tried it but I didn't. I might have learned something. Don't really like blowing primers. CCI primers show less pressure for me than Winchester. Doug
Ive read the posts 2 or 3 times. What kind of primers are you using? What did the other primers look like with the hornady and nosler bullets? Are you living on the edge? If so. Ive had Winchester primers be flat and the same load on the next one pierce and blow clear out on a 6.5 cm. I laid it on to brass cups and started loading a half a lighter charge and changed to cci. Should o loaded the same charge with the cci primers and tried it but I didn't. I might have learned something. Don't really like blowing primers. CCI primers show less pressure for me than Winchester. Doug
243winxb
Member
Same weight bullet- different brand construction.= different pressure.
Another interesting result was that while we were shooting the thicker jacketed bullets both barrels produced several blown primers. The .257 barrel produced 14 blown primers and the .256 barrel produced 5. There were no blown primers while shooting the regular jacket bullets. We did chronograph five shots using regular bullets at a MV range of 2,996 to 3,024 fps. The chronograph was not working later in the day so we could not check the MV produced when shooting the thicker jacket bullets.
http://benchrest.com/showthread.php?49336-Berger-bullet-failure-test
Post #7 covered it well.
Sierra uses 4 different lead alloy cores . Some harder then others.
Another interesting result was that while we were shooting the thicker jacketed bullets both barrels produced several blown primers. The .257 barrel produced 14 blown primers and the .256 barrel produced 5. There were no blown primers while shooting the regular jacket bullets. We did chronograph five shots using regular bullets at a MV range of 2,996 to 3,024 fps. The chronograph was not working later in the day so we could not check the MV produced when shooting the thicker jacket bullets.
http://benchrest.com/showthread.php?49336-Berger-bullet-failure-test
Post #7 covered it well.
Sierra uses 4 different lead alloy cores . Some harder then others.
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antelopedundee
internet bum
I'm not having the issues, someone else on another message board is. I was repeating what he had posted there. The comments in quotation marks in my other posts are what he has posted there. I did ask him for more info tho.
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MilGunsmith
Member
We do testing with pressure measurement at work. Some of our experimental bullets are matched with a similar size and shape commercial bullet to use for equipment set up. There is a difference in load to match velocities.
A-Square did this and reported the result in their manual "Any Shot You Want" pg 153.
antelopedundee
internet bum
A-Square did this and reported the result in their manual "Any Shot You Want" pg 153.
Thanks for posting that. Interestingly, it seems that the Sierras provided slightly higher pressures.
MilGunsmith
Member
We have found that a harder bullet, jacket or core, creates higher pressures given the same diameter and bearing surface.
antelopedundee
internet bum
I'm aware of the precautions. I usually reduce 5% or a grain or 2 or 3 depending on the situation and whether or not pressure numbers are given with the loading data. It can be just as dangerous to reduce too much as it is to load too much esp. for slower burning powders. I've never done a lot of indiscriminate substitution so maybe I've dodged a bullet in the past.
antelopedundee
internet bum
Actually I went out and did that today with my .25-06. I used 117 grain Hornady boattails #2552 and Sierra 117 grain flat base #1640 Pro-Hunter since that's all I have on hand and I've had them for over 20 years so they aren't new manufacture. Tried 53.5 grains of IMR 4831 and 57 grains of IMR 7828 for each. Remington 9 1/2 primers. Serbian Prvi Pritizan brass. Essentially no difference in bolt lift, primer appearance. One case with 7828 and Sierra had a mild extractor mark on the case head, but no other indications of pressure.
So for what I have, I'll use them interchangeably.
I asked him by private message for more info. This was his reply.
"Tom,
I first noticed it with my 7mm Rem Mag going from 162gr SST to 160gr HPBT GameKing. The 160 SPBT GameKing was worse yet.
This transfered over again in 7mm-08 with 140gr Ballistic Tip to 140gr GameKings, both HPBT, SPBT. Again worse with the SPBT.
Then again in the 257 Roberts with 100gr bullets.
Different cartridges, different volumes, different powders.
I have contually had to develop different loads when shooting same weight Sierra's.
Don't get me wrong. I really like Sierra bullet, and will continue to use them! Just realize a 100 gr bullet is not the same accross the board.
Ken"
So I expect that it's the type of Sierra that he's using. I will ask him if he made any changes to the powder weights, etc.
With IMR 7828 Cases that had Sierra bullets are on the left in both pics. Designated pic A
With IMR 4831 Designated pic B
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