Remington 6 1/2 SRP Question

[pengo]

I was hoping someone with more experience than me can offer me some advice, please?

I have a .223 Tikka T3 Supervarmint 20" 1:8 barrel and was going to get some Remington 6 1/2 Small rifle primers that I've seen for sale; but I have seen an advert on here that says they are not suitable for use in a .223......can anyone confirm if this is correct, please?

I am using 77gn SMK's and have been loading with 24.0gn N140 and BR4's.

Looking forward to any assistance.

Cheers.

[Re-Pete]

.223 is a fairly high pressure cartridge, and it's just possible that a standard primer will pop and burn the bolt face........I speak from experience, having once mixed up some spilt KVB Magnum and Standard primers.

My 223 still bears the scars...

Pete

[pengo]

11 minutes ago, Re-Pete said:

223 is a fairly high pressure cartridge, and it's possible that the primer will pop and burn the bolt face........I speak from experience, having once mixed up some spilt KVB Magnum and Standard primers.

My 223 bears the scars...

Pete

Thanks for replying, Pete.

It's not looking like a good idea to use these, then???? 

Oh well, I guess I'll continue with my existing primers and keep a look out for some coming up for sale.

Cheers.
Paul

[Re-Pete]

I use BR4, 450, and Remington 7 1/2 in mine, and I shoot the heavier bullets, 73 to 80.5 grains at velocities up to 900m/s .

Russian KVB-223M were the best "bangs for buck" primerwise, but no doubt thanks to Gollum, no longer available.

Pete

[banus02]

remington state on the 61/2 packets NOT FOR 222/223/etc and they are quite correct !!🤔

[Laurie]

The CCI-400 and Rem 6 1/2 were originally designed for the .22 Hornet, .218 Bee and similar. In addition to these being relatively low pressure cartridges, they needed rather 'soft' (read 'thin') cups as in poorer times than now many rifles were built on converted rimfires, old Martini Cadet and similar actions with weaker and lighter mainsprings/strikers. When Remington introduced the .222 Rem in 1950, a ~50,000 psi cartridge, the 6 1/2 was deemed too weak and the first SR 'magnum', the No. 7 1/2 was introduced to cope with the higher pressure. As with most SR 'magnums', it was no 'hotter' than the standard model, but had a thicker brass cup - 25 thou' vs 20 thou'. (The later / current 7 1/2 BR is more aggressive having been introduced alongside the .17 Rem cartridge that needed a higher brisance primer with some powders.)

 

In the 223, it's always better to use the thicker cup models, although you can 'get away with it' with weaker designs depending on 1) the pressure you handload too. (In a standard shortish freebore chamber the 77 SMK + 24gn Viht N140 would likely be approaching full pressures, rather less with a Wylde or longer freebore chamber.) ........... and 2) the nature of the action and how much clearance there is between the firing pin and its hole in the bolt-face. A loose fit facilitates cratering, and at higher pressures 'blanking' where the metal disk of the pin indentation in the primer cup detaches and either ends up inside the primer or in some action designs is blown back into the bolt body. (The latter happens with ARs and similar with a floating firing pin and no firing pin retaining spring, also thin-cup primers aren't a great idea in such actions anyway, as there is a small risk of a slamfire caused by the pin's momentum as the bolt slams closed under spring power. This is why there are special military spec primers such as the CCI-41 for such rifles.)

 

Cup thickness is as follows for US models

20 thou' ............ CCI-400; Rem 6 1/2

21 thou' ............ Winchester WSR

22.5 thou' ........ Federal 205 and 205M

25 thou' ........... CCI-450 and BR4; Rem 7 1/2 and 7 1/2BR

 

European primers vary. The original Russian Murom / PMC SR primer (KVB-223) with the bright copper colour metal was very thin/soft and blanked easily. The last of the KVB-223s available here before the import ban on Russian stuff was sold as the 'SR Competition' and is sturdier, but can still be blanked with a not massively hot a load in the 223. (I sometimes wonder if this is a procurement or production QC issue rather than the design as it occurs randomly.) The KVB-5,56 and later KVB-223M are both tough primers, the former with a mild explosive pellet, the latter more powerful to cope with some modern ball type powders that need 'warmer' ignition.

 

Fiocchi, PPU, and S&B seem fairly sturdy, but the S&B marque has both 'SR' and '5.56' versions, the 5.56 obviously made to a military spec. Can't comment on Ginex as never seen any, likewise  the RUAG/RWS/GECO (same thing; different labels). However as Nitrochemie uses RWS in its 223 RS40/77 loads data with a max pressure over 58,000 psi, it must be robust.

 

South American CBC Magtech 7 1/2s are as the identification number denotes, a 'magnum' type with a thick cup. IME, it's a tad 'softer' though than the equivalent Remington or CCI SRM / BRs, but is fine in most 223 bolt-actions, and the late 'Bradders' both sold them to his AR shooting customers, and used them himself in CSR loads. (Excellent primers and FAR better value than any US model if you come across any, but strangely they're not 'rated' by most British handloaders.) 

 

If you ever come across 20th century Vihtavuori primers in the old blue and orange packaging, these are the weakest of the weak and blank very easily indeed. (Viht is restarting primer production next year or maybe the year after as a result of the current western European security crisis allied to Finland's accession to NATO that sees it switching from LRP 7.62X39 to SRP 5.56 and one assumes that when its primers eventually reappear for sale to handloaders the SR versions will be 'tough' models.) 

[pengo]

10 hours ago, Laurie said:

The CCI-400 and Rem 6 1/2 were originally designed for the .22 Hornet, .218 Bee and similar. In addition to these being relatively low pressure cartridges, they needed rather 'soft' (read 'thin') cups as in poorer times than now many rifles were built on converted rimfires, old Martini Cadet and similar actions with weaker and lighter mainsprings/strikers. When Remington introduced the .222 Rem in 1950, a ~50,000 psi cartridge, the 6 1/2 was deemed too weak and the first SR 'magnum', the No. 7 1/2 was introduced to cope with the higher pressure. As with most SR 'magnums', it was no 'hotter' than the standard model, but had a thicker brass cup - 25 thou' vs 20 thou'. (The later / current 7 1/2 BR is more aggressive having been introduced alongside the .17 Rem cartridge that needed a higher brisance primer with some powders.)

 

In the 223, it's always better to use the thicker cup models, although you can 'get away with it' with weaker designs depending on 1) the pressure you handload too. (In a standard shortish freebore chamber the 77 SMK + 24gn Viht N140 would likely be approaching full pressures, rather less with a Wylde or longer freebore chamber.) ........... and 2) the nature of the action and how much clearance there is between the firing pin and its hole in the bolt-face. A loose fit facilitates cratering, and at higher pressures 'blanking' where the metal disk of the pin indentation in the primer cup detaches and either ends up inside the primer or in some action designs is blown back into the bolt body. (The latter happens with ARs and similar with a floating firing pin and no firing pin retaining spring, also thin-cup primers aren't a great idea in such actions anyway, as there is a small risk of a slamfire caused by the pin's momentum as the bolt slams closed under spring power. This is why there are special military spec primers such as the CCI-41 for such rifles.)

 

Cup thickness is as follows for US models

20 thou' ............ CCI-400; Rem 6 1/2

21 thou' ............ Winchester WSR

22.5 thou' ........ Federal 205 and 205M

25 thou' ........... CCI-450 and BR4; Rem 7 1/2 and 7 1/2BR

 

European primers vary. The original Russian Murom / PMC SR primer (KVB-223) with the bright copper colour metal was very thin/soft and blanked easily. The last of the KVB-223s available here before the import ban on Russian stuff was sold as the 'SR Competition' and is sturdier, but can still be blanked with a not massively hot a load in the 223. (I sometimes wonder if this is a procurement or production QC issue rather than the design as it occurs randomly.) The KVB-5,56 and later KVB-223M are both tough primers, the former with a mild explosive pellet, the latter more powerful to cope with some modern ball type powders that need 'warmer' ignition.

 

Fiocchi, PPU, and S&B seem fairly sturdy, but the S&B marque has both 'SR' and '5.56' versions, the 5.56 obviously made to a military spec. Can't comment on Ginex as never seen any, likewise  the RUAG/RWS/GECO (same thing; different labels). However as Nitrochemie uses RWS in its 223 RS40/77 loads data with a max pressure over 58,000 psi, it must be robust.

 

South American CBC Magtech 7 1/2s are as the identification number denotes, a 'magnum' type with a thick cup. IME, it's a tad 'softer' though than the equivalent Remington or CCI SRM / BRs, but is fine in most 223 bolt-actions, and the late 'Bradders' both sold them to his AR shooting customers, and used them himself in CSR loads. (Excellent primers and FAR better value than any US model if you come across any, but strangely they're not 'rated' by most British handloaders.) 

 

If you ever come across 20th century Vihtavuori primers in the old blue and orange packaging, these are the weakest of the weak and blank very easily indeed. (Viht is restarting primer production next year or maybe the year after as a result of the current western European security crisis allied to Finland's accession to NATO that sees it switching from LRP 7.62X39 to SRP 5.56 and one assumes that when its primers eventually reappear for sale to handloaders the SR versions will be 'tough' models.) 

Thanks for that detailed reply, Laurie, it's really appreciated.

As a brief aside, would the 6 1/2 work with a lighter 60gn bullet, with a psi of around 43,000 and 23.0gn N140?

There is also the option of the "Geco/RUAG" primers.......

Or should I just right off the whole idea of using 6 1/2 remingtons altogether and go back to my original load and bullets with the CCI BR primer?

Just looking at options before I run out of the CCI

[Laurie]

Don't get rid of them. Light loads will be fine unless your bolt/firing pin fit is really poor, and even then it'll probably just be mild cratering which looks unsightly but doesn't cause any problems.

I'm using up several hundred weak-cup CCI-400s, Rem 6 1/2s and especially a large lot of the original Russian copper colour PMC SRs made by Murom in a 6.5 Grendel Howa 'Mini' 1500. It has a small diameter pin which is a reasonable fit for a factory rifle, and loads that are running a tad over 50,000 psi if QuickLOAD is believed don't see any problems in this respect other than a liveable with level of cratering. It's only when I tip the powder can over-much and hit somewhere around 53,500/54,000 psi that things start to turn nasty.

Let your rifle and the fired primer conditions tell you when to stop or back of a bit.

Have a look at the pic of fired Rem 6 1/2 primers here in 308 Win small primer 'Palma' brass loads

http://www.targetshooter.co.uk/?p=2621

None blanked, but those examples are very heavily cratered and right 'on the edge'. In normal load development, I'd rate the loads too high pressure for this primer model, and either change primer model to an SRM/BR or reduce the powder charge significantly.

In the final part of this SR primer test series, here:

http://www.targetshooter.co.uk/?p=2662

if you scroll down towards the end, there are pics of different small rifle primers fired in my onetime 'hot' long-range 308 Win Palma brass FTR load. I almost got away with it with weaker models as the rifle had a Stolle Atlas action with small dia. pin and fairly close bolt-face fit (but not the perfect fit you get on some custom actions). Only one example of the soft PMC SR blanked.

(Note too the difference in appearance between primer appearance despite these cartridges having an otherwise identical components combination. It's impossible to gauge pressures from primer condition when switching primer makes and models around, (but possible with extensive experience of a single model in a particular rifle with experience and cross-checking MVs against QuickLOAD predicted values and their accompanying estimated pressures).

 

 

 

   

[Re-Pete]

Having read that piece, Laurie, I think I'll try the KVB-223 Standard primers (brass coloured cup) in my 6BR at an MV around 2600 fps, using RS 62. (I have around 900 left).

Pete