.264 High Pressure Signs

[TC8500]

I have a Winchester Model 70 in .264 with a 26" barrel. I went to the range today and shot 9 rounds from the following load. Accuracy was 1" 3 round group @ 100 yards. The measured COAL on this rifle is 3:410

Remington Brass
Federal 215 Primer
61 Grains H4831
Nosler 140 Grain Partition
OAL: 3.310

The above load is listed in the Lyman 44th Edition as the accuracy load, with the data listed starting at 57 grains going to 63 grains. The Hornady Vol II manual dated 1973 lists the starting load at 57.3 grains and going to a max of 66 grains. I am no where close to a max load. However, of the 9 rounds I fired one primer blew and the other eight the primers were cratered so I stopped shooting. I believe that the bullet is seated too close to the lands and that is causing the high pressure. Please give me your thoughts/recommendations on the OAL change, I am looking at Hodgdon's website data and the OAL for this load is listed as 3.260 Looking forward to your input.

 

[243winxb]

264 Winchester Magnum.

one primer blew and the other eight the primers were cratered

55.0gr H4831 is maximum on Hodgons website with the Nosler 140 Grain Partition. The construction & bearing surface of a bullet can raise pressures. You are over maximum pressure, reduce the powder charge for the bullet type.

 

[TGReaper]

For me the 140 gr.bullets are too heavy for the .264. My pet load for my Mod.70 .264 WM. is the Sierra 120 gr.Spitzer ahead of 60.0 gr of IMR 4350 with CCI mag .Primers.
Chronos at 3200.excellent deer and target load.
TGR

 

[10 Spot Terminator]

Sounds like you have an original pre 64 Westerner there. If so you may be partially right in that those rifles had a seriously short throat in them as the original 140 gr. Winchester power point bullet was a double diameter bullet and could be set out full length where standard bullets could not. I actually had the throat professionally lengthened for that very reason as way too much of a standard bullet was pushed deep into the case reducing powder capacity and raising pressures some as well. I have shot alot of H4831 in my Westerner behind 140 gr. Sierras and Speers using Winchester std. and Mag primers as well as Federal 215M primers too. At 63 grs. of H4831 was where the pressures would start to show by measuring the case just above the belt prior to and after firing the round. Never had a primer issue but have only used Win. and Rem. cases. The short throat was in reality a lot of what had earned the .264 Mag the barrel burner reputation where it was throat errosion at the base of the problem . Several after me have had the throat lengthened and report over 1,000 rounds fired with no accuracy loss.

 

[MEHavey]

264WM/140's...

Hornady 6th says H4831/58.8gr Max
Lyman says 61 (SC)
Speer 14th says 57 (SC)
Sierra 3rd says 62
Hodgdon Web says 55
QL says 62gr produces 56,000psi for 2,930fps

Oh what a tangled web we weave ... without a chonograph.

 

[MEHavey]

If you're looking for a really fast 264/Hvy Bullet combo, QL tells me that H870 potentially gives you a full case, 98% burn, 3,000fps+(+) ...for only 53-54,000psi

Take a look at Hornady's manual and work up.
(QL tells me to stop before Hornady's Max)

 

[Clark]

The .264 Win case head is the 1925 300 H&H design.
Primer pocket looseness or stiff bolt lift will be the first HIGH PRESSURE SIGN in a work up.

 

[gamestalker]

By what method have you arrived at the OAL your using? I'm asking primarily because you are running a rather heffty powder charge and thus should be careful not to seat any deeper than is necessary. I like to utilize as much of the throat as possible when I load like that. In addition to accuracy, pressures are more predictable and managable if you run an OAL that is structured to the throat. I also suggest you carefully check your data again for the charge you are using. From what I can tell based on avaiable listed data, you are over the maximum listed data. However, with a slow burning powder compressed loads are not going to produce high pressures to the extent of blown primers, stiff bolt, or head separation if properly worked up. Just be cautious first and formost for your safety, and it would also be a shame to ruin a nice production rifle like that M70.

 

[jerkface11]

For me the 140 gr.bullets are too heavy for the .264.

Yeah it simply doesn't have the case volume for heavier bullets.

 

[Coltdriver]

Have you measured your chamber with the bullet you are using?? If you have not then you should do so immediately.

Chambers vary all over the place and the book is meaningless unless you know what your dimensions are.

Once you know your chamber dimensions I would recommend you look up optimum charge method and work your way up to the most accurate round you can get. That is rarely the hottest round you can load.

 

[NCsmitty]

Yeah it simply doesn't have the case volume for heavier bullets.

It certainly has case volume, and is an over-bore cartridge capable of burning out the throat in 1500 rounds, with hot loads.

If you're blowing and cratering primers then 243winxb's recommendation should be heeded.
If you have checked COAL of the chamber with a slightly sized case holding the Partition bullet, and it measured 3.410", then 3.310" should not be causing pressure problems.

You should look to reducing the charge to at least the 55gr of H4831 that www.hodgdon.com shows as maximum, or you'll end up with expanded primer pockets and junk brass.



NCsmitty

 

[TC8500]

I determined the OAL by the following, I placed a 140 grain Partition in the rifling and then run a cleaning rod down the barrel until it touched the tip od the bullet and then marked the cleaning rod with a felt tip. I removed the bullet, then closed the bolt and ran the cleaning rod down the barrel until it touched the bolt face and marked it. The distance between the two marks was 3.410. Next I made a dummy cartridge using a 140 Grain Partition and inserted it and the rifling showed on the bullet I seated it deeper and tried it until no rifling marks were present on the bullet at which the OAL was 3.310

 

[10 Spot Terminator]

More food for thought here, have you checked your primer seating depth ? If they are a tad high this can accent the cratering effect. Forgot I actually had to use a primer pocket uniformer on my Winchester brass but it barely touched the Remington brass . Again I own no Federal brass so am just doing some what if stuff here ...

 

[TC8500]

Ten Spot Terminator
Thanks for the food for thought, I used a primer pocket uniformer on the Remington brass. As with the advice and recommendations that all have provided I believe I need to go back to square one and start working up a few loads. I have some Nosler 120 Grain BTs so I am going to begin with a 120 grain load first and if all is well I'll proceed slowly with a 140.

 

[TC8500]

264 Problem "Your Recommendations and Advice"

I want to personally thank each and everyone of you who responded to my situation on High Pressure signs with my 264. and your advice will be heeded. I am going back to square one and will start working up a 120 Nosler BT load and once all is well with that load I'll proceed slowly and work up a 140 load. I'll post the results once this is accomplished. Once again a big "Thank You" for all your input.

 

[jerkface11]

It certainly has case volume, and is an over-bore cartridge capable of burning out the throat in 1500 rounds, with hot loads.

Sorry I forgot to indicate my sarcasm in that post. I only shoot 160 grain bullets out of mine. I'm going to suggest a slower powder for the OP.

 

[10 Spot Terminator]

I have a powder reccomendation for your 120 gr. pills that was the best of the best for my 125 gr. Partition loads and that is IMR 7828. Tried this one as was a favorite on many threads for the .264 Winny as their favorite for bullets in te 120-125gr. range for speed and accuracy. My personal load with the 125gr. Partition does sub MOA at 200 yds. clocking 3225 fps. and I couldnt be happier. Live in High Desert country where long shots are the norm and this fits the bill nicely.