Fast way to best results with an M1917
The following repeats of some of my old posts (why reinvent the wheel?) should help you to get the best out of your M1917 in a short time, without endless unnecessary experimentation:
My suggestion for a PDG first approximation:
Powder charge to "accuracy load" for your powder in the Sierra manual, if you plan to shoot at 600 yds or more.
For shooting up to 300 yds, reduce the Sierra "accuracy load" figure by precisely 2 grains. Not 1 grain, as this will put the rifle in a "bad vibrations" area - groups were 2-3x larger for my M1917!
Use 168gn HPBT Sierra Matchking or Lapua Scenar. Seat 0.020" off the lands. I have read of people claiming that they seat down to 0.003" off the lands. Poppycock! When the striker hits the primer, the cartridge is pushed right forwards, by the amount of the head clearance (forget gauge headspace - this is firing real ammo, not gauges!). So when the primer ignites and it all goes bang, the bullet may or may not be hard against the lands. This maybe contact means erratic pressure variation and less than optimum groups.
After first firing, check the head clearance again, with a case that was fired in your rifle. It will probably be very small indeed. From now on only neck-size those cases, and they will last and last and last... and be amazingly accurate. Now you can also try setting the bullets a gnat's whisker closer to the lands, but don't forget that everything has tolerances, including bullet profiles, and you should avoid those maybe contacts.
Expect 2-3 MOA at 100 yards on first firing. Off a sand sack. Well centered horizontally.
If you get below 2MOA, you are approaching the aiming limits with iron sights and your PWF. 1 MOA is testing you and your eyesight. The rifle may be even better, but you need to fit a scope to test it. Mine brings sub-MOA only with a scope off a sand sack. I just can't aim or shoot any better!
Now go out and fulfil these expectations, and post the results!
Good shooting!
M1917 load - find the worst to pick the best
I started off with the load from "visier" quoted above by mk23 (I shoot in the BDMP with the guy who provided those loads).
I had to shorten the OAL because the 83.8 mm put the bullet right up on the lands in my Eddy. I set the depth to be about 20 thou off the lands and tested various charges of N140. No crimp. Look up Optimum Charge Weight and Optimum Barrel Time for an understanding of what is going on, and why and how to test various charge weights.
Bullet: Lapua Scenar Silver Jacket (i.e. the moly-coated version) 167 gn.
Case: GECO 30-06, once-fired in this rifle. Selected by weight to a spread of +/- 1 gn about the 181 gn average value of the batch I had. The average may vary a little from one factory batch to another, but the spread within a batch seems to be very low indeed.
Primer: CCI 200 large rifle
Powder: charges from 46 to 51 gns (max permitted load in Vihtavuori reloader manual is 51.1 gn).
The grouping results were plotted on graph paper. Two curves: one with the group size of all 8 shots per group. Then, allowing for 1 flyer per group, a curve of the 7 shots left after eliminating the worst shot in each group. Result: two double-humped curves - a valley between two peaks.
It is not easy to find the best, but easy to see the worst!
At 46 and 49 gn the 8-groups were twice as large as the groups at 47(good)-48 gn (better). For the best-7-shot groups (i.e. without the worst shot) 45 and 49 gn were MORE than twice as large as the groups with 48 gn. 50 gn was even a touch better, but noticeably harder on the shoulder.
Conclusions: for this rifle, with the load parameters described above, the best load lies around 47.5 gn N140, but is non-critical in this range. Below 47 or above 48 slight variations will produce increasingly larger spreads, and 46 or 49 gn regions are to be avoided.
Of course, this could be repeated with varying seating depths etc. But life is too short and I have other things to do - like shooting other rifles! So, under the motto "No pain no gain" I took the 50gn** load (which must be measured very carefully,as it is very close to the limit) and came 3rd in the BDMP Hessen Championship at 100 meters - 40 places up on the year before! For everyday use, the 47.5 gn is an excellent non-critical first approximation, but first check on the apppropriate seating depth for YOUR rifle!
Patrick
** 50 gn because I wanted to shoot at long range with the same powder charge. Post shoulder-op it has to be the 48gn - which is what a friend uses who is a better shooter than I am.
------------------------------
An optimized M1917 at 50 yards should give nearly one ragged hole for a group. Say 1".
The battle sight aperture is a CWOA* for target shooting.
Much too large, and set for something like 300 yards (the real figure is probably in Ferris' book somewhere).
And using junk milsurp ammo is a CWOM**.
Assuming that the rifle is mechanically OK ....
Use only the flip-up sight.
The backsight aperture can be improved by gluing on a small washer with a hole about 1.4-1.6 mm diameter (1/16") over the existing hole.
Then slice off about 1/8" of black rubber tubing (or a rubber washer) with an outside diameter no more than 3/8" (otherwise it will foul the battle sight when you set it for 100 yards/meters). Glue that on as well. The idea is to produce a smaller backsight aperture with a bit of shading.
The tricky bit is getting it all centered over the original hole.
Use Pattex/Thixofix or whatever that rubbery impact adhesive is called in your country, as it can all be peeled off later without any damage to the bluing, if you want to restore the rifle to its original state.
Paint the washer-ring combination dead black ("blackboard black") to minimize reflection.
Rest the rifle on a sandbag, on the area behind the lower band where you would have your front hand in a normal shooting position. Resting too far forwards encourages the bad vibrations.
Use the 6 'clock hold. Make sure you can see the foresight blade sharply. Seeing the target sharply is second priority. Sharp foresight and fuzzy target is better than the other way around. If necessary get glasses properly adjusted for shooting requirements. Reading glasses are usually set too short, glasses for car-driving are set too long. Not getting this right is a CWOTMAA***.
Do all this and you should see an immediate and considerable improvement.
Please try it out, and let us know how you get on.
And if you really want to know how you and your rifle GROUP after this, you do not want a spotter scope. In fact, you do not need to see the impact holes at all. Simply set the target at 100 yards and fire a 5 to 10-shot string as evenly as you can, allowing 1 minute between shots, closing your eyes to rest them, WITHOUT LOOKING AT THE TARGET IN BETWEEN. Because if you do look, you can hardly avoid making unconscious corrections ("That last shot was a bit off, better aim a touch higher/lower/left/right"), with the result that the next shot may actually be worse. (Thank you RSM Kilpatrick for teaching me that!). And do not worry about making fine corrections to the sights until you are convinced that you have achieved the best possible group. Group first, position afterwards!
Patrick
PS:
*CWOA = complete waste of ammo
**CWOM = complete waste of that stuff which is no longer backed up by gold
***CWOTMAA = complete waste of time, money and ammo
