Home Forums Hunting & Shooting Ask The Gunwriters Remington 7-1/2 primers question

I'd be curious as to those results well. I believe I have some shot strings stored in my silver mountain system of 7 1/2s vs 450s in .308 lapua sp brass with N150 and a 155.5 bullet. The 7 1/2s were slightly faster if I remember correctly. I'll be able to check in a couple of days.

I do not recall seeing "Magnum" on these and I just checked my supply and they say "bench rest".

I'm looking at some old 222 loaded ammo - might of been my dad's. The primers are copper colored. I have not seen primers this color for quite a while. It may be before my time?

Remington 7 1/2s are not nickel plated like many of the others; they retain a copper color.

I'd call it more of a brass color. The only reddish copper primers I've seen were very old.

I've been using 7 1/2s since the early '90s, I have never seen any copper colored .

just some anecdotal information..
there is a NATO / OTAN paper " The Combustion of Solid Propellants" that discusses flame temperature, length and composition of various compositions in section 2.0 of the paper.

The paper seems more focused on the inner cone length than the secondary (visible) flame length (at all but the highest pressures ~100ATM), and specifically considers the two parts of the flame separately.
the pdf is 3.2 megs so I dont think I can attach it, but I could send it to you John.
looking at inner cone length might make for an interesting second look at primer flame photos....
Though I can't say for sure that priming compound fit the category of a "double base propellant"

Mule Deer:

I dug into my older primers and found a 7 1/2 box that doesn't mention magnum or benchrest. The same as what Ramblin_Razorback posted:

https://www.ebay.com/itm/Rare-Vinta...leanbore-cartridges-/124438644539?_ul=IN

I am interested in what you find out with the primer comparison

I have a few left in a box that was purchased circa 1983. Labeled Benchrest and they are indeed copper color.

Forgive me for being particular, but I'd like to be clear on what we're talking about.

Pinkish like copper:



Or "copper color" like brass:

I have been using REM 7 1/2's ever since I bought One of the first .17 cal Rem Model 700's rifles.
They were made for the .17 Rem because of the pressure. As far as 6 1/2's I never liked em even in 222 because I drove em harder than factory.
I considered 6 1/2's junk primers

I still Use 7 1/2's in .17, & 223 if loaded to 5.56 pressure because if you use the same hot loads in either caliber with most any other primers they flatten or end up pierced, & eats away at your firing pin.

. I remember back in the day{70's} Ad's from Remington showing a longer duration flame front, not hotter burning just longer lasting
compared to to other primers, that picture clearly showed the flame front while other primers were already done. That + the much harder Bronze cup.

I still have a bunch of the Rem 7 1/2's, all saying BR, or Benchrest. I don't waste these just to burn up ammo, they special. LOL.

Actually, as I mentioned in an earlier post, 7-1/2s were primarily introduced for the .221 Fireball, which appeared years before the .17 Remington. But same deal: Thicker cup than the 6-1/2s to resist higher pressures.

RP used only 3 digit lot #s back then so there's no way for me to establish manufacture date, or to remember exactly when I got these. I have a box of 6 1/2s that are surely from early 80s that are nickle plated lot #231, lot #175 of 7 1/2s marked SRBR that are copper colored (mid to late 80s), & a later lot of SRBR 7 1/2s #297 that are brass colored (late 80s/early 90s). All other RP primers in my closet are brass colored except an older lot (late 80s?) of 2 1/2s which are nickle plated. No mention of magnum anywhere on my SR stash.

Al Angerman did some work with primer photography that the late Dave Brennan published in Precision Shooting Magazine. It was subsequently reprinted as part of the Benchrest Shooting Primer.

Comparisons were the Rem 7-1/2, Fed 205M, etc. -Al

Dave Brennan also ran an article by Audette on Primers which also included photos in the 90's. IIRC it was Audette's last article before he passed away.

Yes....Al Angerman's article was a follow up to some of the work done by Rick Hornbeck and Creighton Audette. I believe the Angerman article was in '93.

After that article, I tested primers extensively in the big cased .17's, finding some definitive stuff.

Presently, both the 6PPCs and the 30BRs routinely operate in the pressure range that no small rifle primer would have survived back then......

Good shootin' -Al

Well I learned something today. I had thought 7 1/2’s we’re older than 221’s. Thanks MD.

No no MD I don't think so, the 17 rem was introduced by Remington in 1971, the 221 fireball was not introduced until 2007.
I've read many times the 7 1/2 was created because of the .17 rem. and the fact that 6 1/2's were not going to cut it. In 71 I was interested in a .17 as soon as I heard about it. Remington said no small rifle primer at the time were recommended for the 17 rem except the 7 1/2.
Today there is some other primers that could fit the bill, not so then.

They are. By quite a few years. I think now a days some of the cci made for 5/56 and Federal AR SRP are maybe even stronger.

Copper colored like copper not like brass coloring for the old loaded rounds I was looking at.