9mm issues

918v · August 12, 2006, 05:53 PM

Did you know that 9mm Magtech brass, while weighing the same as Winchester, requires a reduction in powder charge of more than half a grain to stay south of max pressure?

Seating bullets in Magtech brass also requires more effort, as the brass seems harder.

The above lead me to conduct a study of brass tension on the bullet. Using new Winchester brass and Hornady 147gr bullets, I seated some bullets using a Redding competition seater, and measured the OAL. To my surprise, OAL varied by .015".

I then took some unfired FC brass and conducted a similar experiment. OAL varied only .003".

I then took some once fired FC brass and the OAL variance was .015".

I groupped the rounds into batches based on OAL and will shoot them tommorrow to see if the rounds on the extreme ends of the OAL spectrum cause fliers. I suspect they will.

To eliminate the case volume variable, I'll reseat the dissimilar rounds to the same OAL.

HSMITH · August 12, 2006, 06:12 PM

Your Redding die seats off the ogive of the bullet, OAL is pretty meaningless in this situation as long as the longest round you load functions in your gun. Use a comparator to see what the casehead to ogive diameter measurements are, I would bet you will see that they are within a thousandth or two with mixed brass. The ogive measurement is also what is important, that is a much more reliable method of getting the bullet jump from chamber to rifling consistent.

What powder are you using for the 9mm experiment? What are you using to determine pressure levels? Does the MagTech also chrono faster?

silicon wolverine · August 12, 2006, 06:16 PM

Ive had crappy luck with the magtech brass ive had. I usually pitch any magtech or a-merc brass i end up with in the recycle bucket. they're not worth the trouble.

SW

918v · August 12, 2006, 07:25 PM

Quote:

Your Redding die seats off the ogive of the bullet, OAL is pretty meaningless in this situation as long as the longest round you load functions in your gun.

I don't have a comparator for 9mm, but why is it that the bullets most difficult to seat end up with the longest OAL?

My theory is that the soft jacket and soft lead core of this bullet cause the bullet nose to force it's way into the seater plug as the seater plug forces the bullet into the case. When using Magtech brass, for example, bullet noses are mangled due to the high seating effort.

Quote:

What powder are you using for the 9mm experiment? What are you using to determine pressure levels? Does the MagTech also chrono faster?

The load is 4.4grs. of WSF and a WSP primer. I measure casewall expansion to gauge pressure due to the tapered case profile and the similarly tapered chamber. The higher the pressure, the more the casewalls expand. Standard factory ammo expands to .390", +P+ expands to .394", and Magtech expands to .395+" with loads that do .390" in Winchester or Federal brass.

Marlin.357 · August 13, 2006, 02:12 PM

.......but why is it that the bullets most difficult to seat end up with the longest OAL?"

My guess is that the press and/or linkage flexes.

918v · August 13, 2006, 06:54 PM

No, the bullet nose compressess and swages into the seater stem which is conical inside. Most of the bullet goes into the case, some of it goes into the seating stem.

Ready for the results???

Well, the results are inconclusive. I ended-up using two loads: 147XTP with WSF and with Universal Clays. The WSF load behaved as I predicted, with point of impact shifting based on OAL. The UC load did not exhibit any POI shift.

I did shoot the best groups of my life, however, the tightest being .25", and amazed a firearms instructor that was teaching a newbie on the next bench over. The worst group was 1", most were half inch, one was .25" and two were 3/8", roughly measured CTC.

I really need a Ransom Rest.

HSMITH · August 14, 2006, 08:15 AM

Case measurements are one part, chronograph speed is the second and more important part when trying to determine pressure levels without the right equipment.

I have reloaded many many thousands of magtech brass in 9mm, 40 and 45. Occasionally I will see a little more effort on the sizing, but it is only slight and less than the variation of say a Winchester case fired in a Sig compared to one fired in a Glock.

My experience tells me that the magtech brass is a little on the soft side, other than that it is fine.

918v · August 14, 2006, 09:26 PM

The batch I bought was super hard. I guess the quality isn't so consistent.

On another note, I finally got my hands on some Starline. That brass is nice! Soft as FC, but readily available.

August 12, 2006, 05:53 PM	#1
918v Junior member Join Date: September 25, 2005 Posts: 1,372	9mm issues Did you know that 9mm Magtech brass, while weighing the same as Winchester, requires a reduction in powder charge of more than half a grain to stay south of max pressure? Seating bullets in Magtech brass also requires more effort, as the brass seems harder. The above lead me to conduct a study of brass tension on the bullet. Using new Winchester brass and Hornady 147gr bullets, I seated some bullets using a Redding competition seater, and measured the OAL. To my surprise, OAL varied by .015". I then took some unfired FC brass and conducted a similar experiment. OAL varied only .003". I then took some once fired FC brass and the OAL variance was .015". I groupped the rounds into batches based on OAL and will shoot them tommorrow to see if the rounds on the extreme ends of the OAL spectrum cause fliers. I suspect they will. To eliminate the case volume variable, I'll reseat the dissimilar rounds to the same OAL.

August 13, 2006, 02:12 PM	#5
Marlin.357 Member Join Date: April 22, 2005 Posts: 28	Stuff Bends .......but why is it that the bullets most difficult to seat end up with the longest OAL?" My guess is that the press and/or linkage flexes.

August 12, 2006, 06:12 PM	#2
HSMITH Senior Member Join Date: June 21, 2002 Posts: 2,019	Your Redding die seats off the ogive of the bullet, OAL is pretty meaningless in this situation as long as the longest round you load functions in your gun. Use a comparator to see what the casehead to ogive diameter measurements are, I would bet you will see that they are within a thousandth or two with mixed brass. The ogive measurement is also what is important, that is a much more reliable method of getting the bullet jump from chamber to rifling consistent. What powder are you using for the 9mm experiment? What are you using to determine pressure levels? Does the MagTech also chrono faster?

August 12, 2006, 06:16 PM	#3
silicon wolverine Senior Member Join Date: April 28, 2006 Location: South dakota Posts: 674	Ive had crappy luck with the magtech brass ive had. I usually pitch any magtech or a-merc brass i end up with in the recycle bucket. they're not worth the trouble. SW

August 13, 2006, 06:54 PM	#6
918v Junior member Join Date: September 25, 2005 Posts: 1,372	No, the bullet nose compressess and swages into the seater stem which is conical inside. Most of the bullet goes into the case, some of it goes into the seating stem. Ready for the results??? Well, the results are inconclusive. I ended-up using two loads: 147XTP with WSF and with Universal Clays. The WSF load behaved as I predicted, with point of impact shifting based on OAL. The UC load did not exhibit any POI shift. I did shoot the best groups of my life, however, the tightest being .25", and amazed a firearms instructor that was teaching a newbie on the next bench over. The worst group was 1", most were half inch, one was .25" and two were 3/8", roughly measured CTC. I really need a Ransom Rest.

August 14, 2006, 08:15 AM	#7
HSMITH Senior Member Join Date: June 21, 2002 Posts: 2,019	Case measurements are one part, chronograph speed is the second and more important part when trying to determine pressure levels without the right equipment. I have reloaded many many thousands of magtech brass in 9mm, 40 and 45. Occasionally I will see a little more effort on the sizing, but it is only slight and less than the variation of say a Winchester case fired in a Sig compared to one fired in a Glock. My experience tells me that the magtech brass is a little on the soft side, other than that it is fine.

August 14, 2006, 09:26 PM	#8
918v Junior member Join Date: September 25, 2005 Posts: 1,372	The batch I bought was super hard. I guess the quality isn't so consistent. On another note, I finally got my hands on some Starline. That brass is nice! Soft as FC, but readily available.