We just had a HEYM "sniper" model rifle in for load development, and I noticed the difference in velocity reading between it and a Sako TRG-41. Both rifles have 27 inch barrels.

All the following were with the Nosler 200 grain Ballistic Tip bullet, Lapua brass Federal 215 primers, and the same lot of VVN 165 powders.

SAKO TRG-41 HEYM
95.0 3071 3198
97.0 3146 3259
99.0 3354 3293

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saeed@ emirates.net.ae

www.accuratereloading.com

Saeed,
Will the unsized cases from the Heym fit the Sako chamber? It would be interesting to measure the bore/groove and chamber dimensions of the two rifles and compare.

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Gerard Schultz
GS Custom Bullets

Gerard,

I am afraid I did not check this out. The gentleman who owns the Heym asked for loads to be developed with the 200 Ballistic Tip bullet.

I just took 50 new cases, and used them in that rifle. When I finished, I loaded them up all for him. He has taken his rifle and ammo with him.

I've had similar results once with 270 Winchester rifles - although I am sure it happens to all calibers.

The 270 were all Mannlicher Luxux models, and I used Norma factory ammo in them. All from the same box. The difference in velocity from the lowest to the hiest was about 150 fps!

All rifles had the same barrel length too.

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saeed@ emirates.net.ae

www.accuratereloading.com

Saeed,
We often take same caliber rifles to the range for load development and find that where there are really big diiferences, the cases from the slow rifle will usually not chamber in the fast rifle. The exceptions to this occurs when the chambers are the same size but the bore on one is looser than the other. We have measured many new rifles substantially over size on bore and groove dimensions. They are often very accurate with jacketed lead bullets but will not group with monometal bullets. With HV and FN bullets we simply make them the right size for the bore once we are aware of the problem.

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Gerard Schultz
GS Custom Bullets

A few years back I got the bright idea of two identical chambers and calibers in order to minimize the amount of ammo to pack in for a hunt. Chambers were cut with the same reamer and headspaced as identically as possible. The second rifle was fitted with a BOSS system to enable tuning the same load. Worked great, except one rifle required one more grain of powder for identical velocity. Turned out the barrel of the slow one had a groove diameter that was larger by three or four ten thousandths. Obviously the bore diameter had a major impact.

HI,
Several years ago,my friend Dick and I both sent our guns to the same gunsmith,to have rechambered in 7mmstw.Mine was a Sako his was a Remington.We both used the same barrels.The smith used the same reamers.Same length,same contour.I got better velocity than he did.We were never sure if it was the actions or the barrels,that made the diffrence.
1GEEJAY
www.shooting-hunting.com

Saeed, I can�t understand this is a case of fast and slow rifle. There is a real difference but in two loadings Heim is the fastest and in one Sako is the fastest.

The 99 gr Sako load seem to be unexpectable high.
Goran