What's Your Opinion...LR Magnum Primers

C

Christchild

New member
This has possibly been discussed but I'll put it up anyway...

It has been my understanding (although I've been off the bench for a few years) that LR Magnum Primers can be used in non-Magnum LR applications, just use the lowest listed Powder Charge and Work Up, respectively. I've done so in .270 Win. with AA3100 behind Norma Oryx 150's with success (Non-Winter).

I would like to try some .270 Win. with AA4350 and some 85 gr. Bullets, with LR Magnum Primers...Yay or Nay?
 
I use them in my 25-06 with 87 grain and heavier hunting bullets. Just like you stated, start low and work up. The powder column is pretty tall so a bit of help is not a bad thing, especially when it's cold outside. For bench accuracy I want the powder to dislodge the bullet and do the work, not the primer. In that case I use the mildest primer I can get. The effect is pretty noticeable in smaller cartridges, not so much in larger cases.
 
Magnum primers are about the powder used. However, using 'em might increase pressures, but will not be unsafe.
Your real issue will be finding 85 grain AA4350(that is not the same as IMR or H4350. Burns a bit slower.) .270 data. None given on Accurate's site. Not seeing data for 85 grain .277" bullets listed anywhere except Barnes. Barnes bullets require Barnes data due to the construction. No AA4350 on their site, but you can contact 'em and ask.
1-800-574-9200 or email email@barnesbullets.com.
 
It's not a matter of can or can't. You can always adjust the charge, if necessary, same as with any other component. A good rule of thumb when changing case, primer, or powder lot number, is to adjust the charge down 5% and work back up to original performance.

The question on primer choice is usually a matter of choosing what performs best in your gun. Magnum primers can cause more velocity spread with powders that are easy to ignite, but can reduce velocity spread with hard-to-ignite powders like the old St. Marks line of spherical powders sold as Winchester and Hodgdon spherical powders.

This article is a useful overview on the subject.
 
I use magnum primers for some powders in 270 Winchester and even in 30-30 Winchester. All the ball/spherical powders get magnum primers. but in 270 Winchester, I shoot a lot of 150 grain bullets with some very slow burning extruded powders. In these instances, it can be worth experimenting with magnum primers to see if there is an improvement. It has also been said by many that magnum primers in such loads are a better choice for a hunt in extreme cold conditions
 
As a general guideline you should use mag primers when your powder charge exceeds 50 grains, or when you choose to use a ball powder such as W748, however I have proved both these rules to be a suggestion more than a requirement. I shoot 460 S&W running 52 gr or H110 using std primers with no issues. I also typically use W748 with std primers as well. I tested both mag primers and std primers in .223 using 69 gr bullets and per my data I saw no measurable difference in performance.
 
re: mag primers Here is a OCW development opinion from: http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134
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7. The primer brand you choose is entirely up to you. Use magnum primers only with magnum chamberings, as their added pressure may distort the OCW conclusions on standard chamberings. One exeption here would be with low density loads, as I believe that magnum primers improve ignition consistency in loads where the powder only fills 85 percent or less of the case.
 
There is a lot of evidence to support somewhat better accuracy in non-magnum chamberings with magnum primers. I've used them in both 308 and 30-06 in the past. With the same powder charges speed was around 10 fps faster and I noted no difference in accuracy so I no longer fool with it. In fact I stopped trying to stock 2 different primers and just use LR primers in my 300 WSM. If I lost any speed or accuracy it isn't enough for me to measure.

It won't hurt a thing to use them if you want. You may need to adjust your loads, especially if you are close to max. You may not, you'll just have to experiment.
 
I use LR mag primers in my Mod 94 .30-30. Only because I load using W748.
It seems to be more consistent. If I load with RL#15, then it's a Std LR primer.
 
It has been my understanding (although I've been off the bench for a few years) that LR Magnum Primers can be used in non-Magnum LR applications, just use the lowest listed Powder Charge and Work Up, respectively.
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Your understanding is correct. They may be of benefit. They may be less consistent. They may not make a difference. Only a test will tell. The practice is not dangerous, and it is a matter of fine tuning. Benefits are most often seen with slow burning powders, or lower pressure straight wall cartridges like 45-70 or 444.
 
Allan Jones, who was involved in primer development at CCI wrote that magnum primers are distinguished by making more gas, which is why they better pressurize the total empty space between grains in a large volume magnum case. He wrote that they also work well with low percent fill charges in standard cases for the same reason: more empty space to raise to a reasonable start pressure. He wrote the CCI magnum primers were also reformulated in 1989 to better ignite the spherical propellants then available at the time (Western says the more modern coatings used for their Ramshot line of powders don't need this), which would include most of Hodgdon's and Winchester's lines of spherical and ball propellants made by St. Marks Powders in Florida. The heavy deterrent coatings need more pressure and higher temperature to light up well. They also started adding more aluminum to make a hot spark shower which they found helps. If you look at the MSDS sheets, you see most domestic primers now seem to include that.
 
qrz wrote:
One exeption here would be with low density loads, as I believe that magnum primers improve ignition consistency in loads where the powder only fills 85 percent or less of the case..
Click to expand...


Unclenick wrote:
Allan Jones, wrote that they also work well with low percent fill charges in standard cases for the same reason: more empty space to raise to a reasonable start pressure.
Click to expand...



Guys, I picked up on your findings regarding LR magnum primers in low volume reduced loads. Because I have noticed an almost linear increasing velocity variation in reload work-ups with H4895 as the powder charge goes down from 85, 80, 75, 70, 65 to 60% using LR std primers.

Thx, Have not heard that before now, but makes sense!
I realize that you are just reporting someone else's finding,
But have you (or anyone here), experience using mag primers in reduced loads.
 
"Allan Jones, who was involved in primer development at CCI wrote that magnum primers are distinguished by making more gas, ..."

My wife claims that if I were a primer I would be a magnum primer.
 
Nothing like a little pride of place! :D:D:D


Ray,

Yes. I've run them with standard Garand loads of about 47 grains of IMR 4895 under the 175 grain SMK's, which fills the case less than 85%. Groups tightened up and SD decreased. But if I have a load that fills the case well, like 49 grains of N135 under a 150 grain FMJ's for as-issued matches, then I find the mild TulAmmo KVB762 primers produce the best precision and velocity consistency, followed by Federal 210M primers.

There was also one shooter at the CMP forum I advised to make the switch who had his groups tighten up.

Change in velocity with charge weight tends to be pretty constant within a range of pressures. Looking for a sudden divergence downward from that is a common pressure sign, as it can mean the chamber is starting to stretch under pressure. To see what I mean by a "range of pressures", for any published load, subtract the maximum charge weight from the minimum charge weight and divide that into the difference between the highest and lowest velocity. This gives you a number of fps per grain in that pressure and velocity range. If, however, you simply divide either velocity by the total charge weight that produced it, you get a little different number, as the linearity goes away at very low pressures and velocities.
 
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