What can you do for the BEST Chamber spec's, to fit the ammo??

[Nvreloader]

Guys,
To help you understand the info I am talking,
Here is a JGS Reamer SAAMI print of the 17 RF WSM chamber,

When I post about a certain measurement,
I'll list the LETTER of the reamer print,
for that location/info, check the reamer print FOR THAT LETTER,
it will make it easier to understand, I hope.

I finished measuring 6 cases (3000 rds) of 17 RF WSM ammo,
1 case of each bullet weight, 20 & 25 grs,
of Win, Hornady and Federal ammo brands,

The below are the following measurements from of all the OEM ammo,
Out of all the ammo measured,
I had 33 rounds TOTAL (from all brands),
that fit within MAXIMUM SAAMI spec's,
most all ammo was smaller/shorter than these dimensions.

All gages were made to the SAAMI spec's shown on the reamer,
for checking the ammo spec's.

Line = Letter V + OB (head space/rim thickness maximum) = 1. 274" SAAMI,
The measurement for the lead was,
Shortest = 1.212"
Longest = 1.232"
Average = 1.218"

Line RB = 1.017" SAAMI,
Datum Line measurement was,
Shortest = .985"
Longest = .994"
Average = .990"

Line AB =.336 min/.341 Max SAAMI
Rim Diameter,
All cases fit within = .336" dia
Average was .333 diameter,

Line OB = .066 min/.071 Max SAAMI
Head Space
Thinnest = .061"
Thickest = .065"
Average was .062"

Line A and Line E = .270 Min/.272 Max SAAMI
Case body dia,
All cases fit within = .2695" diameter,


For the ease of measurements,
I INCLUDED the Head Space dimensions, .066"
for ALL lengths above and I used the SAAMI SPEC'S,
to give a base line.

Each reamer maker has THEIR own way,
of setting their dimensions/measurements etc.
A very confusing to say the least.

Any thoughts, suggestions or Ideas,
to make/have the BEST chamber spec's,
for the greatest accuracy possible,
seeing the minimum spec's of the measured ammo??

Tia,
Don

 

[ireload2]

Don
I think your idea is interesting. It depends on how many rounds you want to discard or shoot in a sloppy facotory chamber. While you have measured a lot of ammo you might need to analyze the data statistically.
1. Take the data for each measurement and find the extreme highs and low. Then compute the standard deviation for the sample size.
Once you have the standard deviation calculate the value of the mean minus 3 sigma and value of the mean plus 3 sigma. That is the 6 sigma limits of the ammo. At 6 sigma there will be 3.4 defects (rounds that fall outside that value) per million round for that feature.
This will give you a better idea of how variable the factory ammo is. The reason for the statistics is they will predict the total variation of the ammo better than your raw data. The total variability of all the ammo produced is even greater than your data shows. The plus and minus 3 sigma will tell you the limits or number of defects you will see in a much larger number of rounds.
If you cannot do this send me your data and I will do the calculations or I can show you how.
All of that hard earned data graph should be graphed too. Put it into bins of .001 and graph it. You should get a normal distribution bell curve.
The rounds that fall in the middle 2 to 4 sigma should be your best ammo. The ammo that falls in the tails of the normal distribution is considered the outliers. The outliers on the big end of the dimensions will be the best fit in the chamber. The outliers (smallest dimensions) on the left end of the distribution will be the loose ammo in the chamber.
2. You can design a reamer to produce a tight chamber for the ammo in the middle of the curve and expect to get the best accuracy from the largest number of rounds. The smaller rounds would still shoot but will not be such a good fit. The bigger rounds will be too tight and would need to saved and fired in a normal factory chamber. Some of the big rounds might be chambered by using a bolt action or single shot falling block with a lot of camming power.
3. You might want to check the neck diameter of the ammo.
4. You might want to check the dimensions of the chambers in the rifles you shoot.
I would bet they are oversize or at maximum dimensions.

The .22 WMR has a pitifully huge and overly long chamber. One shooter remarked that it appeared to have been designed by the rabbits that were going to be shot at with it. It appears to be deliberately sloppy in order to produce the worse accuracy.

 

[waldo1979]

I just sold my highly modified B-mag. Good luck with that =D

Not sure what adjusting the chamber spec would do for ammo quality issues.

 

[/VH]

Don,

When you get done with all that measuring n cyphering, one idea that I would like to mention, if you haven't already done so; call those really nice and helpful folks at JGS and ask them for their insight on the matter.

Brian

 

[ireload2]

Line RB = 1.017" SAAMI,
Datum Line measurement was,
Shortest = .985"
Longest = .994"
Average = .990"

The SAAMI drawing for the cartridge is 1.010 +.000 - .010
So the cartridge high limit is 1.010 and the low limit is 1.000.
Looks like ALL of your ammo is out of tolerance if your measurements are correct.

If you are brave enough to do the research investigate a vented body die to make this dimension as short as is safely possible.
You can experiment on empty brass. The shorter the better to insure uniform ammo.
If you can resize the body of loaded rounds (shoulder bump) to .990 then you will have much less clearance for the ammo. But you would need a non-standard chamber length



Make both the C and H dimensions (neck diameter) about .002 larger than the ammo.
SAAMI says the ammo is supposed to be .197 +.000-.004 so it can get sloppy with minimum ammo.

Make the lead diameters (G&I) about .0003 larger than the largest bullets.

Have you looked at the SAAMI cartridge and chamber drawings?
JGS manufactures no ammo and no rifles so their participation in the over all accuracy results would be very small.

http://saami.org/PubResources/CC_Drawings/newSpecs/17WSM_SAAMI_CC_DWG_Public_Active01-14-2013.pdf

 

[Nvreloader]

Ireload2
(UPDATE, I posted my response to your 1st post, after your second post,
did not know about your second post.)

Thank you for that info,
I'll have to go back thru my notes to obtain the info.

IMHO (at this time),
I am thinking of the following dimensions for a reamer/chamber,
as a SWAG.

1. Line = Letter V + OB (head space/rim thickness maximum) = 1. 274"SAAMI,
The measurement for the lead was,
Shortest = 1.212"
Longest = 1.232"
Average = 1.218"
------------------------------------------------------
Not sure on this measurement yet,
as I have a 17 RF throater to change this dimension,
when I set up a test gage throated to 1.218",
there was less than 50 rds total,
that would drop in and could be pushed tighter.

2. Line RB = 1.017" SAAMI,
Datum Line measurement was,
Shortest = .985"
Longest = .994"
Average = .990"
-----------------------------------------------------
I am thinking of making this measurement at .995",
all ammo measured fit inside this measurement,
which is .022" tighter than SAAMI spec's.

3. Line AB =.336 min/.341 MaxSAAMI
Rim Diameter,
All cases fit within = .336" dia
Average was .333 diameter,
----------------------------------------------------
I will make the rim diameter .336"
as all ammo fir within this diameter.

4. Line OB = .066 min/.071 Max SAAMI
Head Space
Thinnest = .061"
Thickest = .065"
Average was .062"
------------------------------------------------------
Will make the head space at .066",
as all ammo fit within this spec.

5. Line A and Line E = .270 Min/.272 MaxSAAMI
Case body dia,
All cases fit within = .2695" diameter,
-----------------------------------------------------------
Will make the case diameter at .270" straight,

6. Line "O" = Neck diameter= .198" SAAMI
Neck diameter, all ammo fit within .197".

I have measured several hundred fired brass from
several different makes/brands of rifles/pistols,
SAAMI spec'd to custom reamers etc.

To say that they are over sized or maximum dimensions,
is a GROSS UNDER STATEMENT.

There does not seemed to be ANY standard period,
when it comes to the 17 WSM ammo/chambers etc.

My reason for all the measuring available OEM ammo,
seeing that you can only do so much with a RF ammo,
in changing chamber spec's to the best fit.

I don't have any rifle/pistol for this caliber yet,
my reason on attempting to find the best reamer spec's etc.
Then I can build it etc.

Tia,
Don

 

[ireload2]

Don you have an interesting project. I would like to do the same for the .22 WMR but I have never found a suitable action.
I had a long discussion with another enthusiast who reported that the 5mm Remington RF Magnum was very accurate. It easily shot 1" groups at 100 yards. So you might investigate the SAAMI specs for that round for additional data.
I have an old 640K Mossberg and it has the typical sloppy chamber and shot fairly poor at 100 yards. Mostly the groups were 2.5" to 3" with good ammo and 3.5" to 4.5" with the terrible Federal 50 grain plain lead bullet. I actually pulled the factory bullets and seated Sierra 40 grn and 45 grn Hornet bullets and improved the accuracy. I seated the bullets so far out they almost would not stay in the case but they still did not reach the rifling. Even though the accuracy improved to about 2" the rifle is too sloppy without another chamber and or barrel.

 

[CJ6]

I would like to do the same for the .22 WMR but I have never found a suitable action.
.

Get an Annie.

 

[Dusty Stevens]

With no control over ammo its gonna be tuff to tighten it up from the saami specs. If you change anything you may be stuck next year with a chamber that will not shoot the newer lots of ammo

 

[ireload2]

I don't want to spend the bucks for that and wind up tossing the barrel.

Get an Annie.

 

[CJ6]

All RFs are pretty ammo dependent, ....Find what it likes and buy a case or 3. Mine likes the old Win 45gr. JHP ammo.

 

[ireload2]

Your what? Rifle that is.
The best Win ammo seems to be 40 grain in .22 WMR. In my old clunker it is the FMJ ammo.
Most RF are ammo dependent, especially the .22 WMR, because no one experiments with them.
You really cannot do much with a RF if the chamber diameter is grossly over size and the chamber is way longer than the ammo.

All RFs are pretty ammo dependent, ....Find what it likes and buy a case or 3. Mine likes the old Win 45gr. JHP ammo.

 

[Nvreloader]

Ireload2,

Here is the totals for measurements of the OEM loaded ammo,
as close as I can measure the ammo,
with a hole diameter of .234" for the shoulder datum line,
which is Line RB on reamer diagram.

27 rds @ .985" long
29 rds @ .986",
48 rds @ .987",
--------------------------------
360 rds @ .988",
485 rds @ .989",
898 rds @ .990", These lengths seem to cover 90+% of the ammo
451 rds @ .991",
483 rds @ .992",
180 rds @ .993",
--------------------------------
2 rds @ .994",
60 rds @ .995",

As you can see,
this is why I am thinking on the .995" as the maximum length for the chamber,
(which is tighter than SAAMI spec's), along with other changes, involving lead/throat areas etc.
I do realize that the ammo is not within SAAMI spec's, (not much I can do about these spec's),
reason for me obtaining several different lots/brands to have the greatest variation possible.

This reamer will be a RIMLESS design,
that way I can vary the chamber depth as needed when testing etc,
rifles to be chambered will be a SS (NEF) and a Rem SS bolt action,
TC contender pistol.

Tia,
Don


[QUOTE="ireload2,
The SAAMI drawing for the cartridge is 1.010 +.000 - .010
So the cartridge high limit is 1.010 and the low limit is 1.000.
Looks like ALL of your ammo is out of tolerance if your measurements are correct.

If you are brave enough to do the research investigate a vented body die to make this dimension as short as is safely possible.
You can experiment on empty brass. The shorter the better to insure uniform ammo.
If you can resize the body of loaded rounds (shoulder bump) to .990 then you will have much less clearance for the ammo. But you would need a non-standard chamber length



Make both the C and H dimensions (neck diameter) about .002 larger than the ammo.
SAAMI says the ammo is supposed to be .197 +.000-.004 so it can get sloppy with minimum ammo.

Make the lead diameters (G&I) about .0003 larger than the largest bullets.

Have you looked at the SAAMI cartridge and chamber drawings?
JGS manufactures no ammo and no rifles so their participation in the over all accuracy results would be very small.

http://saami.org/PubResources/CC_Drawings/newSpecs/17WSM_SAAMI_CC_DWG_Public_Active01-14-2013.pdf[/QUOTE]

 

[ireload2]

Wow that was a lot of tedious work.

Depending on the mechanical advantage of the rifle it looks like you could start out even shorter than than .995.
At .993 you would only be squashing a few rounds when closing the bolt and that would giver a better fit on everything smaller.
If you are unhappy with .993 or even .992 you can always cut the chamber a few thousandths deeper.

 

[Nvreloader]

Ireload2

2 of the actions will be break action Single Shots, 1-NEF and 1- TC,
the other one will be a multi-lug bolt action, also single shot.

Food for thought,
You have given me another option, to think about,
chamber each of the actions for a certain lengths,
shoot/test the .985, .986, .987, .988 ammo in the .985" length chamber,
shoot/test the .989, .990, .991, .992 ammo in the .989" length chamber,
and use the the rest of the lengths in the .992" chamber,
to see the results etc.

Thanks,
Don

Wow that was a lot of tedious work.
Depending on the mechanical advantage of the rifle it looks like you could start out even shorter than than .995.
At .993 you would only be squashing a few rounds when closing the bolt and that would giver a better fit on everything smaller.
If you are unhappy with .993 or even .992 you can always cut the chamber a few thousandths deeper.

 

[ireload2]

That would be an interesting experiment.
I had considered something similar for testing the .22WMR, only it would have been increasing the length of the same chamber
for each successive test.
In your case you could cut all 3 to the shorter length, then cut 2 to the next length an finally one to the longest length.

Ireload2

2 of the actions will be break action Single Shots, 1-NEF and 1- TC,
the other one will be a multi-lug bolt action, also single shot.

Food for thought,
You have given me another option, to think about,
chamber each of the actions for a certain lengths,
shoot/test the .985, .986, .987, .988 ammo in the .985" length chamber,
shoot/test the .989, .990, .991, .992 ammo in the .989" length chamber,
and use the the rest of the lengths in the .992" chamber,
to see the results etc.

Thanks,
Don