Home Forums Hunting & Shooting AR and Tactical Rifles WSSM's in an AR?

Yes. Welcome Mike.

I am a new member too, and after some good feedback from RickyD and Ridge Runner I am thinking about one of your uppers in 25WSSM.

I started the process by looking at a 6.8SPC or 6.5 Grendel, but I'd like all the horsepower I can get.

I've been visiting your site alot, and making plans for a 25WSSM. <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />

Mike(Dtech)

Yes welcome!!

I don't want you muddying the waters any here on pressures.
Any time you have a specific load, factory included, and you seat the bullet deeper you are reducing case capacity and raising both pressure and MV. Without testing gear you have no clue at what level you are working.

That can be dangerous and lead to issues folks don't want to deal with. The "external" visual signs of pressure rely on lots of things, especially in a gas gun, timing, gas port diameter, brass hardness(brand to brand, lot to lot etc....)

That being said, you don't have a clue what factory ammo is running pressure wise in a barrel and what deep seating the ammo does to the pressures.

I don't know what the accepted pressure is on a wizzum round but would think that in the AR it should be 50-60 kpsi max.

Now that I've said all that, I have done and continue to do and experience like you do, I have access to a pressure tester from a friend and tend to send stuff to him if in doubt. I'm mostly a 223 shooter in matches but try to keep my ammo to the 60kpsi level or less and have had no issues.

BUT I also know that things can be cumulative. If max is 50kpsi and you are running 60 or more, it may not blow today or the next, but it may well do it later down the line after being beat up each time it goes off.

I am like you though so far. I've run many rounds at 60 and have no pressure signs really visible and have had no issues at probably well over 50 thousand rounds fired. And IIRC the 223 specs claim either 50-55 kpsi max.

Remember I'm not so much arguing with you as stating that you cannot have any clue as to what the pressure is unless tested and what reseating does without testing.

An example though an extreme is that you'll usually get the same MV from the same pressure all else being the same. I shot 75 amax loaded to engage rifling for prone slow fire matches. It shot so well I tried the accuracy of seating them to mag depth. Accuracy was super and had some stupendous scores at 300 rapid fire at Perry a few years. Ugly rounds but accurate. BUT I also had to back off almost 2 grains to keep the MV(and supposedly the pressure) the same.

Sounds like I'll have to have one of your uppers one of these days though.

I'm just trying to keep everyone safe here as this AR forum doesn't have quite the experiences as others and lots of us that have slept with and driven the platform to the tune of 10-20K rounds a year since 1991(personally)

Again, welcome!
Jeff

Jeff, You must have assumed I didn't have the ability to measure the pressure. Building AR's is my "second life". I spent the last 30 years in electronics and have a full set-up with strain gauges to read pressure. In fact, pressure measuring equipment is not the only "hold over" from my first life that has been a huge boon to working with new cartridges. As I said, I shot several un-altered shells for a base-line. I didn't come here to get into any kind of "wee wee match" with anyone. As I stated before: If I wasn't sure it was safe, I wouldn't post it.

I'll make sure not to "muddy" any more water here.

Mike

Yes, my bad. My apology. Its so easy in typing to lead others astray. I went back and re-read quickly(on lunch break from a class) and did not see anywhere it mentioned strain gauges, piezos etc... just saw the word pressure and signs.

Had you said it was 50kpsi(I'm interested in what it actually read) and reseating in this instance read 50kpsi then I'd have said many thanks for doing the work correctly vs others just guessing.

I'm still standing by the fact(CYA) that reseating any ammo changes the pressures or certainly can in many instances.

No muddy water, no pp contests. Just a slight miscommunication. Please understand and accept.

BTW what pressures did it take to toast that bullseye round? I'm interested in that myself.

Jeff

Actually I did say "measure" but didn't qualify it with the method. My rig is based on the same equipment as the ones put out by Ohler. They don't read out in kPSI or CUP. You need to have a "standard" that gives you a base-line with that receiver. Then you can tell if the load is higher or lower and by how much. I have never used standards, I have used it as a comparison to known loads. Like I said in my first post, I shot several un-altered loads for a base-line. I just have mine hooked up to a Fluke digital storage scope. I can store and measure time, and pressure.

The destructive testing was done at the Olympic Arms factory in Olympia Washington. During the WSSM project I made two trips out to the plant but didn't bring my equipment out. I would have liked to have had a strain-gauge on that chamber. It was pretty impressive.

Hi Mike,

Great to have you here!

When you say to seat the factory bullets back .015 is that so they will fit in the mag. or to keep the bullets off the lands? or both?

TK

its so they'll fit the mag, my mag is a lil different from currant ones, the 120 gr factory loads will fit my mag, but in the supreme line even the 85 gr SBT's have to be set back a fuzz.
RR

It's just so they will fit in the magazine.

Thanks Mike, RR.

Mike, I'm doing my taxes today, we'll see if you need to warm up your lathe!

Thanks, Tom

LOL! The poor lathe hasn't cooled down since August! Normally during the winter months I have 5 or 6 builds on my clip-board, I now have 14. By this time last year, things had begun to slow down a little.....not this year. I have been running a little over 2 weeks for the average build. Customers seem to accept that length of time fairly well.

Mike,

Can you PM me with prices for a 25 WSSM to fit on my rock river lower?

I have not read it here, but all of you who have the wssm's in the AR, are there not difficulties forseen for the connection pins? I mean, the rifle was designed for the little .223. Won't the added recoil/pressures cause premature wear on the lower where the pins hold the upper?

Just wondering.

THATS BEEN TAKEN CARE OF 06, the sheer weight of the massive wssm bolt slows everything down causing no more wear than a 223. not sure what all else has been done but you don't notice any violent bolt thrust when firing a wssm.
RR