# Sig 357 flash hole



## BK (Dec 30, 2007)

Anyone have an idea why the flash hole is smaller then normal on Speer 357 sig round?


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## denner (Jun 3, 2011)

More than likely Speer uses high grade low flash powder in their premium ammunition would be my guess.


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## BK (Dec 30, 2007)

The reply from Speer, still no real info as to why the hole is smaller???? Not a real answer Speer, seems like you guys are beating around the bush..

"The design and performance are credited to the engineer and we feel we make the best 357 Sig duty product a shooter can get. Small flashhole, high output primer and a bullet designed for the 357 Sig and not the 9mm combine to give superior performance".


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## Steve M1911A1 (Feb 6, 2008)

Speer did answer your question, and quite completely too.
They wrote, in part: "Small flashhole, [and a] high output primer...designed for the 357 Sig and not the 9mm combine to give superior performance..."

The smaller flash-hole, used with a high-output primer, "squirts" hot fire right into the middle of the powder charge, permitting the use of propellants better suited to the specific cartridge.
The smaller flash-hole might also be a requirement of using a faster-burning propellant, the smaller diameter reducing back-pressure into the case's primer pocket.


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## denner (Jun 3, 2011)

Yep, I agree with Steve 100%. Evidently Speer has engineered all the right elements to obtain the small flash whole w/ superior performance in .357 sig. BK, if you loaded, or had experience in reloading your own ammunition it would make more sense to you. A high grade low flash faster burning propellant , high output primer, bullet specifically designed for the .357 Sig are all elements. Ammunition manufacturers are in very high competition w/ one another(especially for LE contracts), they are not going to give you all of their highly detailed secrets of their engineers and evidently there is no one answer, but a combination of the elements Steve described. Like making the perfect cake so to speak.


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## BK (Dec 30, 2007)

Steve

Thank you. You provided a more direct an understandable reason. Such as fire Into the middle of powder charge...I was looking for more detail, I see its the same for the 6.5 round....thanks

The brass is from a federal agency, and I have a load of it. Just getting back into reloading an pulling the webs off my dillon 650, I was surprised about the small falsh hole since this was the first time for me running into this....


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## BK (Dec 30, 2007)

Denner

I do reload but stepped away for a few years. Just starting back an ran into the small flash hole, first time reloading 357 sig. I admit I have some catching up to do....lol

Thanks for the info guys.


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## naildrivingman (Aug 26, 2013)

I've been researching this issue for about a week now and the consensus out there is mixed on what to do regarding the small flash hole.  Here is the information I have assembled, whether it is true or not, I can't say, but a lot of it makes sense in its own right:

Here are the Whys?
1. The small flash holes correspond to the relationship of the primer and powder
a. One post I read claimed that Speer had developed a proprietary blended powder for maximum performance in LE rounds
b. One post I read claimed that Speer has used a small ball powder and was concerned about the powder filling the flash hole and causing problems
c. I've also read-like above in this forum-that the small flash hole minimizes/eliminates primer pressure setback issues

Here are the "What to do about it"
1. Accept the small flash hole and work with it
a. Decap with a universal or RCBS (I guess their pins are the smallest on the market)
b. Resize with .40 first followed by .357 sig (apparently eliminates lube) or lube and size with .357 sig

2. Drill out the flash hole
a. Measure the flash hole of a spent round and duplicate that size (I've seen references to .078 as the size)
b. Drill the flash hole once and you are done

Here's where I need a little input. I don't like the idea of manipulating components. For whatever reason, IMHO the flash hole are small and should stay that way. I would rather buy a universal decapper (BTW my Dillon decapper blows through the bottom of the case and mushrooms the exterior side of the flash hole) or machine down my Dillon decap rod to pass through the OEM hole. I think enlarging the flash hole with a drill is asking for problems.

I also would be interested to hear from others what your experience is with bullet setback and how you dealt with it. Recipes would be cool to hear about too.

Thanks,
CH


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## rex (Jan 27, 2012)

If you are having a setback problem,you need more neck tension to hold the bullet.You can call the die manufacturer and get an undersize sizing die.Some guns are just hard on bullets chambering,any polishing that can be done to slick up the feeding cycle helps.Minor setback isn't a big deal unless you're running the edge of pressure,anything over .010" I don't like.

I agree with you on the flash hole,it's that size for a reason.That's a pretty high pressure round,you don't want pressure escaping past the primer,which is why I believe they use the small hole and special primer to contain it.Normally it's light loads that start breechface erosion but high pressure can cause primer piercing.This round generates pressures above a 357 mag and it's contained in a smaller package with faster pressure ramping.


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