Different bullets of same weight and charge

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BJung

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A local reloader I talked to last week said he was going to develop a nice load with a 150gr Hornady so he'll have a general idea what he can work around for testing Barnes 150gr bullets. This will save money.

I did a short search of compared loads using different brand bullets of the same weight and would like to know anyone's experience of developing loads with different brand bullets of the same weight with the same powder. Was your charge the same or close? This would save time going through the whole range of testloads, saving time and money.

Theoretically I think there will be a difference because the shape of the bullet and its construction varies. Yet, given the weight of the bullet and the harmonics of the barrel, shouldn't the charge be close? Given my limited experience shooting, the ideal MV for a rifles I planned to shoot was close to the MV to my discovered ideal charge.
 
There will be a difference. I haven't done the exact experiment you're talking about, but I've done one very similar. Same boolit, same charge. Only difference between the two was, one batch was sized and lubed with a traditional lube, the others were powder coated then sized as well. In a 10mm, the Lee 180 grain boolit. Lube was slower by about 15 fps, but with a smaller spread. I didn't test accuracy.

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I don’t understand what he means by “an idea what he can work around”. What does that mean? What’s he trying to do? FWIW, a Barnes bullet is all copper and very different from a Hornady bullet. Not only in composition, but in length due to being lighter than lead vol per vol. Does he own a loading manual or two? Barnes has their own load data for their copper bullets and it’s often very different from lead/copper bullets.
 
He lives near but we've only communicated by email so far. His plan to is find a good load with the 150gr Hornady. Then, since the weight and powder is the same, test loads +/- from what's best using the Hornady load but use the Barnes. The idea is to use less Barnes bullets.
 
I totally missed that he was going to compare a hornady to a Barnes. Yeah, as stated above, the solid copper Barnes will be longer, and take up more case space with the same oal(the same oal probably won't be used) but that 150 hornady data will be useless for the Barnes data. Monolithic bullets will have a decent reduction in charge weight given the same pressure. They just take up more space in the case.

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NoSecondBest said:
I don’t understand what he means by “an idea what he can work around”. What does that mean? What’s he trying to do? FWIW, a Barnes bullet is all copper and very different from a Hornady bullet. Not only in composition, but in length due to being lighter than lead vol per vol. Does he own a loading manual or two? Barnes has their own load data for their copper bullets and it’s often very different from lead/copper bullets.
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^^^This.

While one can do this to a degree with bullets of similar construction and composition, the difference between a cup and core jacketed and a monolithic copper is day and night. Sounds like the "friend" is not very experienced. In the long run, he will not save monies, but waste monies, because anything he develops with the Hornadys will be worthless for the Barnes.
 
I'm not too experienced with this too so that's why I'm asking. I thought it might be a good idea because I can test two rifle test loads instead of one. The time I have shooting is limited and the number of tests I want to do is large.
 
I get the impression that your friend feels if he develops a good and accurate load with a 150gr Hornady, that will be a good starting point for the use of a 150gr Barnes.

Not really. If the good Hornady load is near max, that would hardly be a good start with the Barnes.

I have 3 rifles in .270 caliber. One does best with a 150gr Hornady spire; the second does best with a 140gr Hornady SST. The third does best with a FLAT base Speer 130gr bullet, but spits the Speer 130gr Boat Tail all over the place.

However your friend developed the Hornady load, he will have to repeat the process with the Barnes. I don't think there are any shortcuts.
 
short cuts make for long delays, hopefully only to the gunsmith, not the ER.

Different bullets can have different over all lengths. This can cause reduced case capacity and give higher pressures.

Different bullets can have greater bearing surfaces (amount of bullet that touches the barrel), causing higher pressures.

Follow the manuals, work your loads up, be safe
 
You might substitute bullets of the same size, weight and CONSTRUCTION and be within the safety margin, but changing bullets of the same wieght and different construction is an entirely different matter and a safe powder charge for on might not be safe for another.

And, construction includes the bearing surface size and even the hardness of the alloy the jacket is made from.

If the plan is to work up a load with a (cheaper) Hornady bullet and then just seat an all copper Barnes bullet of the same weight he's ASKING for trouble.

and, he might just GET it!
 
Ok, that makes all perfectly good sense. I'll meet him tomorrow for the first time and let him know.

44AMP, you bring a topic I mentioned on another thread. I don't have my information here but hears the deal. About 15 years ago I did a test for my 7rm within the safety margin and found a good node. I have the MV. I've decided on shooting that 7rm again but with a different powder. My following that charge that the node was produced and within the safety limits of the new powder, will I come close to the node of a new charge of new powder. I never done a ladder test using the same bullet and different powder and compared results to know and maybe someone has.
 
There's no way to know without trying. If you achieve the same velocity using a faster powder, more of the total bullet acceleration happens near the peak, which has to be higher for that reason, and less happens near the muzzle than with the slower powder. This means the quicker powder has the bullet going faster at an earlier point in the bullet's travel down the barrel, so the bullet gets to the muzzle in a shorter period of time. This means achieving the same velocity with two different powders gives you two barrel times, only one of which may be within your sweet spot timing.

Will the difference in your two powders be big enough to do that? Only testing in your rifle will tell you. I know from experience, though, that powders that produce the lowest velocity spread often are not the same ones that produce the best short range accuracy, so the barrel time thing is real and testing is not easy to avoid.

The problem is that more than one variable is being tuned with each charge weight change, so it is the attempt to identify the fewest shots that take all the variables into account in one test series that is vexing. If your gun has a barrel tuner, you can shoot a series of ten or fifteen shots to find a velocity flat spot and then use the tuner to bring barrel vibration into synchronization with rounds loaded in the middle of the flat spot. That still requires additional shots for the tuner, though, so you can still wind up with 50 rounds down range to tune that one component combination. Without a tuner, it can take more because you are messing with seating depth to change the velocity/barrel time relationship. Or sometimes you just luck into it almost right away. Only testing will tell.
 
There are no safe shortcuts.

When you change anything, be it tooling, component, or test platform, start low and work up slow.
 
If using bullets of similar construction the difference is usually not enough to matter. I'd strongly advise backing off on my powder charge when changing when 1st switching to another bullet even of the same weight and working back up. But in my experience I almost always end up finding the same powder charge will work.

But the solid copper bullets use VERY different load data compared to conventional lead bullets. Copper is a lot lighter and a 150 gr copper bullet will be much longer than a 150 gr conventional bullet
 
I didn't think of it earlier and last night looked up my 7.7 Arisaka initial ladder tests results. My 7.7-150gr Barnes using grouped best with 48gr R19. My 7.7-150gr Hornady SP grouped best at 47.6gr and 48.2gr R19. I haven't followed up with further tests yet. I think that as long as I'm within a safety zone, I'm ok.
 
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