SRP In Place Of SPP

[35isit]

I know with the current shortages these questions are being asked. I've not seen an answer to my question. I've come into a few SR magnum primers. I want try them with my 358156 and 231 and AA#7. They will be shot in a Contender or a Dan Wesson Supermag. I intend to obviously start at minimum loads. Do I have to reduce the minimum load further? If so, how much? A chart of the brisance (if that is correct) like a powder burn chart would be nice.

[JM7.7x58]

http://castboolits.gunloads.com/show...-Rifle-Primers

[USSR]

Do I have to reduce the minimum load further?

Short answer: No.

Don

[bluejay75]

Never used SRM primers but SRP is my standard for the majority of my 38 special, 357 magnum, 360 DW and 357 Max.

Only ran into problems once. Max charge of Unique pierced primers shooting the 200 grain Lee RCBS clone at 6 grains. Shot well though.

[dannyd]

Use them all the time in my Rugers and Contenders no problem. 20,855 30/20 rounds out of the TC using Unique and SRP.

[dannyd]

I know with the current shortages these questions are being asked. I've not seen an answer to my question. I've come into a few SR magnum primers. I want try them with my 358156 and 231 and AA#7. They will be shot in a Contender or a Dan Wesson Supermag. I intend to obviously start at minimum loads. Do I have to reduce the minimum load further? If so, how much? A chart of the brisance (if that is correct) like a powder burn chart would be nice.

I miss IHMSA

[Larry Gibson]

Use them all the time in my Rugers and Contenders no problem. 20,855 30/20 rounds out of the TC using Unique and SRP.

If the load is worked up using the SR primers and not exceeding pressure limitations of the firearm then it can be safe. However, merely substituting the SR primer for the SP primer in a load developed with the SP primer can generate much higher pressures than the firearm my be capable of handling.

[Conditor22]

https://www.youtube.com/watch?v=NGVR...annel=SuperVel



even though this says everything is about the same I still have questions.

when I switch from sp to spm my groups change drastically.

Logic makes me wonder if somewhere there is a problem with this test???

[Larry Gibson]

Conditor22

Your logic is correct. There is a lot "wrong" with that test and I would not infer much of anything based of the data provided. There is no information provided other than the cartridge about the powder, bullet or test barrel used. Even then a 3 shot sample for each pressure test tells little. The 5 shot sample for each velocity test is a bit better indication but can easily be misleading. That reason is "random dispersion". There is a reason SAAMI uses a minimal 10 shots for each test.

Here is part of a test I did;

Test Alliant 2400 powder (14 gr) in the 357 Magnum with a 358156 GC’d cast bullet using 6 different primers.

All measurements were taken during testing conducted on 29 April, 2019. Data recorded with an Oehler M43 PBL using Contender 357 with 7.9” barrel. A 2 ½ power scope was used on the Contender.

Temperature ranged from 80 to 82 degrees.
Humidity was 30%.
Barometric pressure was 29.63.

A2400 = Alliant 2400 of current manufacture (purchased 2 months ago)
Velocity in fps is at muzzle.
Velocity SD/ES is fps.
PSI is the pressure (pounds per inch) recorded via the Oehler M43.
PSI SD/ES is the pressure (pounds per inch) variation of the test string.
Group = target at 50 yards with ctc measurement of 2 widest shots.
All test strings were 10 shots.

The 358156 were cast in a Lyman double cavity mould.
Alloy was a soft one made of RL + Pb + tin.
Bullets were AC’d 10+ days before size/lubing and BHN runs 10 – 11.
Bullets as cast are .359+ and were size/lubed in Lyman 450 with .359 H&I die.
Lube used was BAC.
Hornady GCs were seated in the 450 with GC seater prior to size/lubing.
The bullet weight, fully dressed, was 162 gr.

All charges of the Alliant 2400 were 14 gr (+/- 0.1 gr).
All test charges were thrown charges with a Lyman 55.
Charges were verified between each 10 charges thrown on an Ohaus 10-0-5 scale.
Cases were Winchester brass 357 Magnum cases.
Cartridges were loaded using RCBS dies on CH press.
Primers are as indicated using 3 standard SP primers and 3 magnum SP primers.
Bullets were seated to 1st crimp groove (the 358156 has two) for an OAL of 1.597”
A heavy rolled crimp was applied.

---Primer---------Powder----- Velocity----SD/ES-------PSI-----------SD/ES---------Group

Federal 100
----------------------A2400--------1572-------16/46-------38,400-------1200/4000-------5.1”

CCI 500
----------------------A2400--------1551-------15/39-------35,400-------1500/5100--------4.87”

Win WSP
---------------------A2400---------1536-------14/49-------34,800-------1200/4300--------3.75”

Federal 200
Magnum---------A2400----------1566-------15/46-------38,900-------2000/5800--------3.15”

CCI 550
Magnum----------A2400----------1581-------17/51-------39,000-------2100/6400-------3.55”

Winchester
WSPM------------A2400----------1607-------12/37-------41,600-------2700/9000-------2.85”

The SAAMI MAP for the 357 magnum cartridge is 35,000 psi. The PSI of of this test is a bit higher than the results of a recent test. The difference being from the 20+ degree difference in the test ambient temperature between tests and probable +/- result differences between separate tests. While a SR primer was not used during this test there were 3 different SP standard primers tested and 3 different magnum SP primers tested.

We see from the results of this test having sufficient sample number of shots there can be a great disparity of pressure when just different primers are used. My standard load with this cast bullet and Alliant 2400 was developed with WSP and CCI primers in moderate temperature ranges. Here those 2 primers gave psi measurements right at the SAAMI MAP in 80+ degree ambient temperature. I was surprised at the high pressure the Federal 100 primer gave as that primer is generally considered to be a "mild" primer. All 3 of the magnum strength primers gave psi measurements above even the SAAMI MPSM for the 357 magnum cartridge. The load with the Winchester WSMP primer was very stout to say the least.

From the minimal testing done with the 9mm cartridge in that test chart it may have been safe as suggested by the results......however, I would not bet on it. The fact that " when I switch from sp to spm my groups change drastically" is telling you something.......

[dannyd]

loaded 67,123 rounds of 357 magnum mostly using 3.8 to 4.0 W231 or HP-38 don't do full house loads.

[green mountain boy]

why is it gone....# 4106

[Conditor22]

Thank you Larry for taking the time to test and post this, this makes more sense than the link to someone else's test and data I posted.