Help with possible 270 WSM pressure signs?

[Gtscotty]

Hello THR,

I've been a member of the forum for quite a while, but this is my first foray into the Handloading and Reloading section. I have been reloading 30-06 for almost a year, but just started loading up 270 WSM yesterday (for a tikka t3 24in barrel). All of the cases i've used have been previously unfired. I first started out following the speer reloading manual, with a 130 gr SPBT, cci200 primers, and working up from 62gr to 66gr of RL19. These loads shot ok (~1.5", 3 shots) but seemed to be especially dirty, and I was seeing marks on the cases where gasses had blown back nearly halfway down the outside of the case wall. Also, I got the following velocity numbers:

62gr - 2992 fps
63gr - 2943 fps
64gr - 2994 fps
65gr - 3051 fps
66gr - 3068 fps

These numbers were all well below the published velocities, and combined with the blowback I thought perhaps i was not getting good ignition from the cci 200 primers. I went back home last night and decided to cautiously follow the data in my Lymans 49th for the 130 gr swift Scirocco because I felt I needed to use magnum primers and this data uses WLRM ( know switching bullets in loading data is bad ju ju...). Fast forward to today, and I had great results at the range (<1", 3 shots) , especially in my bottom load of 64gr and top load of 67 gr. My velocity numbers were more in line with published standards, with the top load being perhaps 50 fps high:

64gr - 3077 fps
65gr - 3158 fps
66gr - 3228 fps
67gr - 3303 fps

There was no bolt sticking, and the primers did not look terribly flat. After I got home however, I got paranoid and started measuring the case webs. The unfired case webs measure .547"-.548", my cases loaded with 67grs measure .554, and my cases loaded with 64grs measure .553. Incidentally, all of my cases fired with the weaker cci 200 primers measure .553 - .554...... The primers fired with my top load of 67gr exhibit the slightest bit of flow around the firing pin, while it cannot really be seen with the naked eye, when I run my fingernail over it, it catches the slightest bit. My initial thought was to back off to 66.5 gr and see how that goes, but then I got kind of paranoid. I guess my question to the collective THR is, is this kind of web expansion and slight primer flattening attributable to the high pressure nature of this round, or have I found a bad primer/powder/bullet combination that should be avoided?

Sorry about the wall of text. I'll post some pics below, any thoughts or tips would be very much appreciated

 

[Gtscotty]

Here are the promised pics.

From left to right: cci200/63gr, WLRM/64gr, WLRM/67gr


From left to right primer view: cci200/63gr, WLRM/64gr, WLRM/67gr

Does this amount of primer flattening look acceptable?

Top of WLRM/67gr case


From left to right side view: cci200/63gr, WLRM/64gr, WLRM/67gr, unfired brass


An example of some of the blowby I was seeing with the cci200 primed cases.


Thanks again THR for any help/ wisdom yall might be able to pass on!

 

[NCsmitty]

Brass for WSM is usually thicker overall than say '06 brass, because it's a fairly high pressure round. Your primers appear normal, and the smoking down the case past the shoulder, indicates to me lower pressures that fails to obturate the case fully to the chamber. This allows the powder residue to blow by.
Your use of a magnum primer appears to help with the ignition, and is fine when working up loads, although usually the standard primer works well with Rel-19.

www.alliantpowder.com lists 66gr of Rel-19 as a maximum on their site with a 130gr bullet, using CCI 200 primers. Remember that each rifle is a individual, and the maximum load can vary between rifles.
Previously unfired brass will expand to the rifle's chamber, so your web expansion is normal under the circumstances. You need to see what the sizing die does to the once fired brass. The cartridge schematic drawing shows the case base at .555".


NCsmitty

 

[Josh45]

The primers look normal to me as well. I don't see any bulges or anything?

 

[gamestalker]

My two cents worth. All of the cases and primers look good. Regarding the blow by, I have to agree it is likely a cause of sub pressure loads for that particular case design. Those WSM's operate at high pressures than do most conventioanl cartridges.
If extraction is normal and primers aren't flowing severely out to the edges of the pocket, your not seeing high pressure indications. Web expansion is also normal, but again only to the extent there are no extraction issues.
When working with slow burning powder applications which I feel RL19 qualifies for that cartridge, you'll sometimes experience blow by when the powder charge is below optimum charge weight. Back when I began loading decades ago I was rather paronoid about exploding my gun also, especially since I was loading for a .270 win. and the powder I was using produced a compressed charge at the maximum weight, and nearly compressed on the low side. The result of this paronoid approach lead me to loading at the low end and experiencing blow by and terribly inconsistent velocities. A dear friend of mine at the time, who is no longer with us, was an accomplished bench rest shooter and took the time to walk me through the process of evaluating and properely loading with slow burning powders. I was terribly nervous about pulling the trigger on my 700 the first time with his compressed charges, but I quickly realized his advice and teachings were accurate and consistent, as were the loads he developed for me.

 

[gamestalker]

One more tid bit to chew on. Is your ammunition and chamber completely free of any lube, gun cleaning solvents, or other elements? Even a small film of the above can cause some of what your experiencing.
It's been a while since we've discussed the importance of case seize, and what happens when something such as lubes or solvents, or even moisture can impaire this important reaction during case expansion during the pressure building phase.

 

[243winxb]

270 wsm

All of the cases i've used have been previously unfired.

Undersized brass could allow blowback using starting loads as they have not fire formed/expanded to the chamber.

These numbers were all well below the published velocities,

Yours-66gr - 3068 fps. Alliant data-66.0-3088 fps. This is not well below. The Web measurement is under SAAMI, but after a few loadings, extraction may become sticky.

The primers fired with my top load of 67gr exhibit the slightest bit of flow around the firing pin, while it cannot really be seen

I see it in your photo. A sign of high pressure. The amount of flow is determined by the diameter of the hole the firing pin sits in.

is this kind of web expansion and slight primer flattening attributable to the high pressure nature of this round, or have I found a bad primer/powder/bullet combination that should be avoided?

With only 1 sign of possible high pressure, you should be ok.

 

[Gtscotty]

Thanks for all the input, when dealing with things that could potentially blow up in my face, I appreciate having the opinions of folks who are more experienced than myself.

I was surprised to see that the loads made with cci 200 primers were (apparently) not igniting the powder charge sufficiently to seal the chamber and generate full velocity. Before working up these loads, I tried to read as much as I could in the load data available online as well as in my Lymans 49th, and plenty of folks seemed to be doing well with RL19 and LR primers. The significant jump in velocity I noticed after moving to WLRM primers was also a surprise, and I guess lends some credence to the theory that the powder needed a little more kick to light properly. I saw the Alliant powder data, and noticed that they prescribed 66 gr of RL19... They do however, as you stated, use the cci 200 in their load, and I decided that if I was going to fudge a component of the load, it would be safer to sub the speer 130 gr for the swift 130 gr in Lymans load, than to sub a WLRM primer for the cci 200 called out in Alliant's guide... I'm glad to hear that some web expansion is normal, the expansion does not seem to be entirely uniform around the circumference of the case, but from what i've read on the internet, I guess that is also fairly normal?

The primers did not have any bulges, and other than the case expansion at the web, the rest of the case appears to be free of bulges as well.

I'm glad yall are onboard with the idea of the initial loadings not generating sufficient pressure to properly seal the chamber. This was my first thought when I saw the gas blow by, and it seemed to be further supported by the fact that it stopped when I changed to magnum primers. The chamber was as free of lube and solvents as I could get it. I don't really have a good method to make sure the chamber is entirely dry, to date I have just been wrapping some cloth or paper towel around a bore brush, and then doing my best to swab the chamber area out. How do all of yall dry your chamber after cleaning the barrel? Thanks again for all the help.

 

[Gtscotty]

Yours-66gr - 3068 fps. Alliant data-66.0-3088 fps. This is not well below. The Web measurement is under SAAMI, but after a few loadings, extraction may become sticky.

Very true, Alliant does cite 3088 as the velocity for this load, I was meaning to compare it to Speer's velocity data for the same load, which i believe calls for something like 3230fps... I wish the load books didn't differ so much... you never know which one to trust. Its especially bad for the other cartridge i'm about to start loading, 35 whelen, the numbers for that round are all over the board.

I see it in your photo. A sign of high pressure. The amount of flow is determined by the diameter of the hole the firing pin sits in.

Would you deem that an excessive amount of flow? Is any amount of flow excessive? Out of 4 rounds I fired at with the top load of powder, flow can only be felt on one, and only then with a finger nail. The other 3 rounds do not exhibit cratering. I guess this is part of my question, I'm not sure whether some of this expansion/flatter primers than i'm used to with 30-06 is due to the 270 wsm being a high pressure cartridge, or whether I'm significantly over pressure.

With only 1 sign of possible high pressure, you should be ok.

Which one are you counting? The slight primer flow? Or the web expansion?

Thanks again for the input!

 

[T Bran]

Now that you have fire formed your cases things could change a little so if you decide to stay with the 67 grain loading keep an eye on it. Your pressures may actually come down a bit since the usable volume in the case has increased. When you resize your cases for the next loading you may want to try neck sizing a few and full legnth sizing a few. All of my guns are different some are better when I neck size while my 300 Win Mag is much better when I full legnth size just enough to touch the shoulder.
Have fun and be safe.
T

 

[243winxb]

The primer does not have an excessive amount of flow, besides, only 1 primer has it. As far as the web expanding, old reloading manuals do not want the web to expand at all. But this is a new age, with firearms working at higher pressures than the 30-06. Not sure if the no expansion rule applies anymore. If the primer pockets become loose after a few firings, then you know for sure your over pressure.

 

[Gtscotty]

I think I'm going to load up some more rounds at increments between 66 grs and 67 grs of RL19 and see how they do this weekend. I really like the 67 gr load, not only did it achieve excellent velocity, but the first two rounds went pretty much into the same hole, and I pulled the last one to open up the group to .437"...Its only three shots, but not bad for someone who isn't really a standout shot. With this in mind, I don't think i'm going to give up the 67 gr load just yet, but I will definitely keep a weather eye out for excess pressure. I appreciate all the information yall gave, this is exactly why THR is my favorite gun forum!

 

[PCCUSNRET]

I just shot a box of Winchester 243 Win and a box of 7mm Magnums and the primers look just like the one in your 3rd round to the right. I wouldn't think Winchester would be loading excessive pressure loads but I could be wrong. I think your signs to look for with this brass would be oversized (stretched) pockets, difficulty in removing brass from the chamber, split necks and case head separation. It is very hard to tell if a flattened primer was caused by excessive pressure or soft brass.

 

[Outlaw81]

I don't have a 270 wsm but do have various 7mm and 300wsms. Make sure after resizing that ur bolt closes easily. After that go ahead and load a bullet to desired length. If it still closes easily ur on track. All of my short mag brass looks like that. As long as there isn't long cracks in the neck or you don't get a deafening blast in ur face when fired, ur OK. Improper resizing is what will cause resistance when chambering the round. U run the risk of a low pressure blow back if u do it wrong. Brass prep is one of the keys to accuracy. Don't worry if the necks get a little dirty. Just run a patch bout every five shots and that residue will clear a little. You wont get rid of it all tho. With short mags you don't have to use magnum primers either. The increased pressure by the case design allows for a more efficient burn. That's why u get more of a pop rather than a shove with these guns.

 

[steve4102]

When measuring expansion you compare your fired handloads to the expansion of a fired factory round, not a new unfired round. Or compare the fired handloads to each other starting with a mini charge. You also should measure with a .0001 Micrometer not a .001 caliper.

 

[Gtscotty]

Outlaw, when you say improper sizing will cause problems, do you mean accidentally pushing the shoulder back or something like that? I was planning on following T Bran's advice and sizing it until i just barely touch the shoulder, so as to avoid some of the repeated expansion and contraction of the brass everytime i fire/reload. Is this how you resize your wsm's? If so does this cause problems? BTW, I went back last night, and all of my fired cases will chamber in the rifle easily.

Steve, I was indeed comparing my handloads to unfired rounds instead of factory. Just to clarify I wasn't measuring the case head, I was measuring just ahead of the web, about .16 - .18 inches from the extractor cutout. Also, I noticed that my top end loads only had .0005-.001 more pressure ring (i guess thats what the area is called) expansion than my low end loads. I know I need a micrometer but I don't have one for the same reason I don't have a box of factory ammo... terminal cheapness. I think I will probably be biting the bullet and picking up both sometime in the near future. Thanks

 

[Outlaw81]

Ur fired cases will feed easily because they have been formed to the chamber. U still need to neck size the brass again. The shoulder is what I was talking about. When I set my dies I always give them an extra quarter turn after they bottom out on the case. Try not to over lube ur brass too. Short mags are a little thicker than others and you'll need to lube the inside of the necks a little.