243, LRP vs SRP brass

[Southern shooter 59]

I am having a .243 built and I need to buy some brass. I am aware of the advantages of SRP brass if you are wanting maximum load for a particular bullet. Since I am not looking for the maximum velocity with this rifle, should I buy the SRP brass anyway or stick with the LRP. I have primers for both. I will be using this for PRS or hunting.

 

[Mark W]

I would go LRP if you’re planning to use for hunting in cold weather.

 

[Zero333]

Shooting light bullets with faster powders I'd go with small pocket. For heavy bullets with slow powders large pockets.

And like Mark said... In sub freezing temps large pockets with any primer but CCI is best.

 

[Dusty Stevens]

I go lrp on a 243 on anyday. Ive done a bunch of testing with a 243 and the lrp will agg better overall

 

[rafale]

I have good luck with Peterson 243 SRP but it was with N 165 and CCI 450 I Believe a simple base powder is more
easy to ignite vs double base.

Michel

 

[Laurie]

I have good luck with Peterson 243 SRP but it was with N 165 and CCI 450

N165 is a very easy powder to ignite. I did some testing of 175/180s in 7mm-08 with very heavily compressed N165 loads using Winchester LRP and reformed Lapua 308 Palma SRP brass and both performed well despite nudging 50gn charges. (My usual 7-08 load uses 47gn and a bit N160 in SRP brass and it performs just fine all year round even in ambient temperatures in the 30s/40s.)

I have seen reports on the AS forum suggesting some other slow burning grades don't perform well in SRP 243 brass in target usage, H1000 specifically mentioned. I also found 308 Win 'Palma' brass FTR loads using Hodgdon CFE223 in the mid to high 40gn range wouldn't ignite properly with the SR primer I was using - two misfires in 50 rounds and everything else a short-delay hangfire. So, one has to be careful with SRP (and also with the small - 1.5mm - flash-hole as this has a major impact in itself) brass as to both shooting conditions and powder. For hunting or other field use in year round conditions I'd always use LRP brass for the 243.

 

[dminn1]

N165 is a very easy powder to ignite. I did some testing of 175/180s in 7mm-08 with very heavily compressed N165 loads using Winchester LRP and reformed Lapua 308 Palma SRP brass and both performed well despite nudging 50gn charges. (My usual 7-08 load uses 47gn and a bit N160 in SRP brass and it performs just fine all year round even in ambient temperatures in the 30s/40s.)

I have seen reports on the AS forum suggesting some other slow burning grades don't perform well in SRP 243 brass in target usage, H1000 specifically mentioned. I also found 308 Win 'Palma' brass FTR loads using Hodgdon CFE223 in the mid to high 40gn range wouldn't ignite properly with the SR primer I was using - two misfires in 50 rounds and everything else a short-delay hangfire. So, one has to be careful with SRP (and also with the small - 1.5mm - flash-hole as this has a major impact in itself) brass as to both shooting conditions and powder. For hunting or other field use in year round conditions I'd always use LRP brass for the 243.

I run Lapua Palma brass converted to .243 with RL-26 , 105 Berger Hybrids, and CCI 450 primers for steel shooting in the fall and winter months in Tennessee. We get some cold weather here and I have had 100% reliability and very good accuracy with this combo in cool weather. This past week I was experimenting with H-4350 to develop a more stable hot weather load as I have trouble keeping the RL-26 loads in the sweet spot when the temps climb above 75 or so. I used Tula 5.56M primers in these loads and had short delay hangfires in all 25 shots. I suspect this was primer related but I have not been able to try these loads with CCI 450's yet. This leads me to believe that SR primer .243 brass is on the edge of reliability with some powder/primer combos and your advice on running LRP brass in most situations is sound.

 

[Laurie]

This leads me to believe that SR primer .243 brass is on the edge of reliability with some powder/primer combos

The more I look at small to medium size cartridges that use SR primers and have the 1.5mm dia. flash-hole, the more I believe they are as a rule sensitive to primer make and model. maybe even production lot. I saw a straightforward substitution of Rem 7 1/2BR primers for Fed 205s in 6.5X47L transform a poor grouping / mediocre ES combination into one that performed very well on both metrics indeed last year. This left the rifle's owner, a very experienced handloader who has used Federal primers alone for many, many years scratching his head!

I was also intrigued to see Bill Alexander, father of the 6.5 Grendel say on the 'sticky' thread for preferred loads on the 65grendel.com forum write that he recommends those starting out with the cartridge to try a particular 108gn bullet, work up to a max load of Ramshot Tac, and to use his own words: "Then play primers......." with a few make/model suggestions. With around 27-30gn charges, the little Grendel isn't exactly posing a hard ignition challenge, but this implies the SRP sensitivity applies even here.

 

[dminn1]

The more I look at small to medium size cartridges that use SR primers and have the 1.5mm dia. flash-hole, the more I believe they are as a rule sensitive to primer make and model. maybe even production lot. I saw a straightforward substitution of Rem 7 1/2BR primers for Fed 205s in 6.5X47L transform a poor grouping / mediocre ES combination into one that performed very well on both metrics indeed last year. This left the rifle's owner, a very experienced handloader who has used Federal primers alone for many, many years scratching his head!

I was also intrigued to see Bill Alexander, father of the 6.5 Grendel say on the 'sticky' thread for preferred loads on the 65grendel.com forum write that he recommends those starting out with the cartridge to try a particular 108gn bullet, work up to a max load of Ramshot Tac, and to use his own words: "Then play primers......." with a few make/model suggestions. With around 27-30gn charges, the little Grendel isn't exactly posing a hard ignition challenge, but this implies the SRP sensitivity applies even here.

For sure primer sensitivity is critical in tuning these smaller charge cases. I think in the medium capacity cases some combinations using small primers, and slow powders, are so close to reliable or not reliable ignition that it could well be hard to final tune the load by changing primers. As you indicated above, even lot variations of the same primer can throw you out of tune. All of this is dependent on powder/primer combinations. In the .308Win using Lapua Palma brass, I have no problem with ignition reliability and am able to tune using primers with several different powder, primer, and bullet combinations. I suspect the medium burning speed of the powders used has a lot to do with the ease of tuning and good reliability. I use Varget, H-4895, and IMR8208XBR in .308Win.

 

[fyrewall]

Some time ago I acquired a 6.5X47 Lapua sort of unintentionally. Not much choice of primer size or brass - what you see is what you get - one brand (Lapua), one primer size (small).

Doing research on primers I happened upon this:

https://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf

Table 1 made me select Remington 7 1/2's. I use mostly H4350 but with the recent shortage of H4350 I used H414 and Ram Shot Hunter with 140 bullets and Rem 7 1/2 primers. No problems even at moderately cold temperatures like 25 deg. F.

Lot variations occurred with the Fed 205 primer, like 176.5 psi for lot 1CW306 and 208.0 psi for lot 13X416. This would substantiate claims of less than satisfactory performance using that brand of primer, should it be a marginal slow burning powder performer, upon changing primer lot.

The tiny little Rem 7 1/2, as tested, provided 334.0 psi peak blast pressures. The SD was 27.0 and that exceeded either that of both lots of the Fed 205 M. The blast pressure of the Rem 7 1/2 approached that of the CCI 200.

The Rem 7 1/2 appears to be one frisky primer.

Since I am only a casual shooter all I can relate to are 1 to 1.5 inch groups at 300 yards. The report analytical data appear to support my happy Rem 7 1/2 use without a laboratory with lots of expensive analytical stuff. No, I don't sort primers.

The report, logically, attributes blast wave intensity to primer size and explosive content. The report also has some interesting observations about match type primers. I like to look at numbers & graphs.